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2. Particle sources. 1. Electron sources Thermionic sources Field emitters Laser sources 2. Ion sources 2.1 Production of high currents of single charge state ion beams Penning sources Hot cathode sources RF sources 2.2 Production of high charge state ions - PowerPoint PPT Presentation
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Imperial College London 1
2 Particle sources 1 Electron sources
Thermionic sources
Field emitters
Laser sources
2 Ion sources
21 Production of high currents of single charge state ion beams
Penning sources
Hot cathode sources
RF sources
22 Production of high charge state ions
ECR sources
EBIS sources
Laser sources
Imperial College London 2
2 Particle sources
23 Production of negatively charged ion beams
Surface Production
Volume Production
3 Extraction of particle beams
31 The space charge limit and Child-Langmuirs law
32 External and internal fields in the extractor laminar flow and pierce angle
33 The beam emittance the acceptance of the extraction system and the conservation of phase space
Imperial College London 3
Electron sourcesOnly very little energy is necessary to free electrons from the bound state or the
Upper levels of the ldquoelectron gasrdquo in solids This can be done by
1) Thermionic emission
The heated electron must
have an energy higher than
the workfunction
2) Photoemission
The photon energy must
exceed the work function
3) Field emission
high external electric fields
alter the potential barrier
and allow electrons to be
extracted by the tunneleffect
Imperial College London 4
Current density as a function of Binding energy and temperature
Material A (eV) Temp (deg K) J (Acm2)
Tungsten 60 454 2500 03
Thoriated W 3 263 1900 116
Mixed oxides 001 1 1200 1
Caesium 162 181
Tantalum 60 338 2500 238
CsOW 0003 072 1000 035
Richardson-Dushman equation
curr
en
t
Diode characteristic
Temperature limited
Space charge limited
voltage
kTo
eTAJ
2
Imperial College London 5
Thermionic guns
Imperial College London 6
Field emission of electrons from surfaces
Fowler Nordheim
J emission current density (Acm2)B field-independent constant [AV2]E applied field (Vcm) work function (eV)
EeEBJ
51071086
2
Imperial College London 7
Field emission of electrons from surfaces
Single carbon nano tube (CNT) and CNT arrays for the production of high brightness electron beams
Field emitter arrays designed for the production of large panel plasma screens
Imperial College London 8
Photo effect
20 2
1vmEE
chfhE electronkinpot
lightlightphoton
free electrons
bound electrons
light
uv- lampzinc-plate
glass
f
photo cathodeLight ()
ring anode
+ -IpA
U (I=0) U
h
f
Imperial College London 9
Photo effect and laser sources
2390 Laser
Laser
r
QEPJ
Imperial College London 10
Photo effect and laser sources
DESY PITZ 2 source (LC XFEL)
Imperial College London 11
Production of high currents of single charge state ion beams
For efficient ion production the electron energy should be app 2-4 times the
ionization energy of the ion
The impact of electron with gaseous atoms is mostly used for the
production of ion beams
Imperial College London 12
Production of high currents of single charge state ion beams
A Townsend gas discharge using an avalanche effect is an very effective way to produce a high amount of ions Therefore the Paschen criteria has to be fulfilled To improve the gas
discharge and to enhance plasma confinement magnetic fields are used
Imperial College London 13
Penning sources
The Penning Ion Source or PIG source (Philips Ionization vacuum Gauge) invented by Penning in 1937 uses a a dipole field for plasma confinement
The strong magnetic dipole field gives high efficiency as electrons oscillate inside the hollow anode between the the two cathodes at each end
The Lifetime of the source limited by sputtering of the cathodes especially for highly charged heavy ion operation
Imperial College London 14
Magnetron sources
The Magnetron ion source which was first presented by Van Voorhis in 1934 uses a solenoidal magnetic field for plasma confinement The field of ~ 01 T is generated with an external solenoid surrounding the ion source The chamber wall serves as anode while the cathode provides electrons through thermionic emission The filament mounted parallel to the magnetic field forces the electrons to spiral As with Penning sources the Lifetime of the source limited by sputtering of the cathodes especially for highly charged heavy ion operation
Imperial College London 15
Hot cathode sources
Filament Ion Source
Discharge in the plasma chamber is driven by the electrons delivered by the filament
1048774single charged ions up to 100 mA
bull Plasma enclosure by magnets
bull Pressure range 10-1 - 10-3 mbar
bull Discharge voltage 20 - 200 V (depending on ionization
voltage)bull Discharge current 10 - 500 A
100 m m
copperiso lator
w ater
steel
brass
m agnets
ground-electrode
screening-e lectrode
plasm a-electrode
B x
B z
C oSm -m agnets
gasin le tcathode
solenoid
filter-m agnet
Imperial College London 16
RF sources
Non resonant excitation of plasma by RF Only lower charge states available (low electron energy)
but high beam currents possible
Internal antenna to feed RF power into plasma =gt limited lifetime of antenna due to sputtering strong coupling of RF into plasma and good plasma confinement
Imperial College London 17
RF sources
Production of large ion currents (Igt1 A) of single charged ions for surface
treatment or plasma heating (tokamaks) Multiaperture extraction therefore difficult to feed beam into conventional accelerator structure
External antenna to feed RF power into plasma =gt Long lifetime of antenna but chamber has to be of non conducting material
Imperial College London 18
Production of high charge state ions
The PLASMA created is increased in density by electron
bombardment The maximum charge state that will be obtained depends on the incident electron energy
e + X = X+ + 2e
For multi-charge states
e + X i+ = X (i+1)+ + 2e
higher electron energies are required since electrons have to be removed from inner shells The maximum charge state is limited by the incident electron
energy
Imperial College London 19
Electron Cyclotron Resonance Sourcehf = cyc = (em) B
Radial and axial magnetic field distribution for the confinement of the source plasma
Only at the centre of the source the cyclotron condition for the electrons is full filled
(01-1 kW)
Extracted ion currents for different charge states of Argon
Imperial College London 20
Electron Cyclotron Resonance source
By variation of the longitudinal enclosing magnetic mirror configuration the
charge distribution can be influenced
Schematic layout of an ECR source for the production of radioactive
ion beams
Imperial College London 21
Electron Beam Ion Source
nominal valuesmax
valuesunits
electron beam current 350 1300 mA
electron beam energy 20 275 keV
trap length 12 - m
magnetic field 15 5 T
charge per pulse 1-2 4 nC
ion pulse length 005-100 - micros
containment time 20-2000 - ms
Parameters of CRYSIS Upper First EBIS IEL-1 build by Donets in 1968 lower Evolution of charge state distribution of nitrogen ions at Ee=545 keV
17 cm
CRYogenic Stockholm Ion Source
Imperial College London 22
Electron Beam Ion Source
Ion current extracted from an EBIS as a function of the
charge state for Na ions (Ne gas was added)
Comparison of the extractable (electric)
current between ECR and EBIS
Total ion charge trapped in an EBIS as a function of confinement time for different electron beam currents
Imperial College London 23
Laser Ion Sources
Schematic drawing of the experimental set up of a laser ion source By the impact of the laser with the target a plasma is created which expands
in the drift chamber and then is accelerated in the extraction gap
Imperial College London 24
Laser Ion Sources
The different charge states of the plasma are separated by the drift longitudinally and reduce space charge in the acceleration gap
By interaction of the plasma electrons with the electric field of the laser pulse the electrons are heated This leads to a shift of the charge state distribution of the plasma ions towards higher charge states
Imperial College London 25
Laser Ion Sources
The available laser power density on the target (for fixed total laser power influenced by beam size on target) strongly influences the charge state distribution of the plasma
The different charge states of the plasma are separated by the drift longitudinally (higher charge states first) and reduce space charge in the acceleration gap
Imperial College London 26
Production of negatively charged ion beams
Three Types of H- Ion Sources are in use
bull Surface conversion sources
bull Volume production sources
bull Hybrid production sources
Conserving energy when forming a negative ion through direct electron attachment the excess energy has to be dissipated through a photon A + e = Amacr + But radiative Capture is rare (5bull10-22cm2 for H2)
Higher cross sections (~10-20cm2 for H2 and Ee gt10 eV) can be realized when the excess energy can be transferred to a third particle M + e = A + B + e and sometimes = A + Bmacr
Cs can be used as an electron donator but the ionisation energy of 39 eV is much higher than the 075 eV electron affinity of H- =gt Surface treatment
Even better are processes which excite a molecule to the edge of breakup (vibrationally excited 4ltnlt12) and then dissociated by a slow electron
Imperial College London 27
Production of negatively charged ion beams
anode
cathode
gasin let solenoid filter
extractore -gtHslow
-driver
e -gtHfast 2
Magnetic dipole fields can be used as filters
to create areas of different electron
temperatures
Cross sections for different production
and destruction mechanisms
Imperial College London 28
Sources using surface production
Schematic layout of the LANCE surface source using a filament driven gas discharge for plasma production and surface conversion on a Cs target for H- formation
Picture of the LANCE surface source
Imperial College London 29
Sources using volume productioncopperm agnetiso latorwater
plasm a-cham ber
plasm a-electrode
screening-e lectrode
electron-dum ping
solenoid bending-m agnet
soleniod
cathodeand
gasin let
filter-m agnet
grid
The small experimental H- source in Frankfurt used a hot cathode driven gas discharge dipole fields and a Pt surface
cover for the reduction of the dissociation of the H2 molecules
Imperial College London 30
Sources using hybrid production schemes
The RAL H- source uses a Penning discharge (dipole for plasma
production and to influence electron temperature) and Cs injection
The SNS H- source developed in Berkley uses RF to produce the plasma dipoles to influence the electron density and a Cs collar
Imperial College London 31
The extraction of particle beams
Imperial College London 32
The space charge limit and Child-Langmuirs law
Imperial College London 33
The space charge limit and Child-Langmuirs law
Imperial College London 34
External and internal fields in the extractor laminar flow and pierce angle
Imperial College London 35
External and internal fields in the extractor laminar flow and pierce angle
Imperial College London 36
The beam emittance the acceptance of the extraction system and the conservation of the phase space
Imperial College London 37
The beam emittance the acceptance of the extraction system and the conservation of the phase space
Imperial College London 38
The beam emittance the acceptance of the extraction system and the conservation of the phase space
Imperial College London 2
2 Particle sources
23 Production of negatively charged ion beams
Surface Production
Volume Production
3 Extraction of particle beams
31 The space charge limit and Child-Langmuirs law
32 External and internal fields in the extractor laminar flow and pierce angle
33 The beam emittance the acceptance of the extraction system and the conservation of phase space
Imperial College London 3
Electron sourcesOnly very little energy is necessary to free electrons from the bound state or the
Upper levels of the ldquoelectron gasrdquo in solids This can be done by
1) Thermionic emission
The heated electron must
have an energy higher than
the workfunction
2) Photoemission
The photon energy must
exceed the work function
3) Field emission
high external electric fields
alter the potential barrier
and allow electrons to be
extracted by the tunneleffect
Imperial College London 4
Current density as a function of Binding energy and temperature
Material A (eV) Temp (deg K) J (Acm2)
Tungsten 60 454 2500 03
Thoriated W 3 263 1900 116
Mixed oxides 001 1 1200 1
Caesium 162 181
Tantalum 60 338 2500 238
CsOW 0003 072 1000 035
Richardson-Dushman equation
curr
en
t
Diode characteristic
Temperature limited
Space charge limited
voltage
kTo
eTAJ
2
Imperial College London 5
Thermionic guns
Imperial College London 6
Field emission of electrons from surfaces
Fowler Nordheim
J emission current density (Acm2)B field-independent constant [AV2]E applied field (Vcm) work function (eV)
EeEBJ
51071086
2
Imperial College London 7
Field emission of electrons from surfaces
Single carbon nano tube (CNT) and CNT arrays for the production of high brightness electron beams
Field emitter arrays designed for the production of large panel plasma screens
Imperial College London 8
Photo effect
20 2
1vmEE
chfhE electronkinpot
lightlightphoton
free electrons
bound electrons
light
uv- lampzinc-plate
glass
f
photo cathodeLight ()
ring anode
+ -IpA
U (I=0) U
h
f
Imperial College London 9
Photo effect and laser sources
2390 Laser
Laser
r
QEPJ
Imperial College London 10
Photo effect and laser sources
DESY PITZ 2 source (LC XFEL)
Imperial College London 11
Production of high currents of single charge state ion beams
For efficient ion production the electron energy should be app 2-4 times the
ionization energy of the ion
The impact of electron with gaseous atoms is mostly used for the
production of ion beams
Imperial College London 12
Production of high currents of single charge state ion beams
A Townsend gas discharge using an avalanche effect is an very effective way to produce a high amount of ions Therefore the Paschen criteria has to be fulfilled To improve the gas
discharge and to enhance plasma confinement magnetic fields are used
Imperial College London 13
Penning sources
The Penning Ion Source or PIG source (Philips Ionization vacuum Gauge) invented by Penning in 1937 uses a a dipole field for plasma confinement
The strong magnetic dipole field gives high efficiency as electrons oscillate inside the hollow anode between the the two cathodes at each end
The Lifetime of the source limited by sputtering of the cathodes especially for highly charged heavy ion operation
Imperial College London 14
Magnetron sources
The Magnetron ion source which was first presented by Van Voorhis in 1934 uses a solenoidal magnetic field for plasma confinement The field of ~ 01 T is generated with an external solenoid surrounding the ion source The chamber wall serves as anode while the cathode provides electrons through thermionic emission The filament mounted parallel to the magnetic field forces the electrons to spiral As with Penning sources the Lifetime of the source limited by sputtering of the cathodes especially for highly charged heavy ion operation
Imperial College London 15
Hot cathode sources
Filament Ion Source
Discharge in the plasma chamber is driven by the electrons delivered by the filament
1048774single charged ions up to 100 mA
bull Plasma enclosure by magnets
bull Pressure range 10-1 - 10-3 mbar
bull Discharge voltage 20 - 200 V (depending on ionization
voltage)bull Discharge current 10 - 500 A
100 m m
copperiso lator
w ater
steel
brass
m agnets
ground-electrode
screening-e lectrode
plasm a-electrode
B x
B z
C oSm -m agnets
gasin le tcathode
solenoid
filter-m agnet
Imperial College London 16
RF sources
Non resonant excitation of plasma by RF Only lower charge states available (low electron energy)
but high beam currents possible
Internal antenna to feed RF power into plasma =gt limited lifetime of antenna due to sputtering strong coupling of RF into plasma and good plasma confinement
Imperial College London 17
RF sources
Production of large ion currents (Igt1 A) of single charged ions for surface
treatment or plasma heating (tokamaks) Multiaperture extraction therefore difficult to feed beam into conventional accelerator structure
External antenna to feed RF power into plasma =gt Long lifetime of antenna but chamber has to be of non conducting material
Imperial College London 18
Production of high charge state ions
The PLASMA created is increased in density by electron
bombardment The maximum charge state that will be obtained depends on the incident electron energy
e + X = X+ + 2e
For multi-charge states
e + X i+ = X (i+1)+ + 2e
higher electron energies are required since electrons have to be removed from inner shells The maximum charge state is limited by the incident electron
energy
Imperial College London 19
Electron Cyclotron Resonance Sourcehf = cyc = (em) B
Radial and axial magnetic field distribution for the confinement of the source plasma
Only at the centre of the source the cyclotron condition for the electrons is full filled
(01-1 kW)
Extracted ion currents for different charge states of Argon
Imperial College London 20
Electron Cyclotron Resonance source
By variation of the longitudinal enclosing magnetic mirror configuration the
charge distribution can be influenced
Schematic layout of an ECR source for the production of radioactive
ion beams
Imperial College London 21
Electron Beam Ion Source
nominal valuesmax
valuesunits
electron beam current 350 1300 mA
electron beam energy 20 275 keV
trap length 12 - m
magnetic field 15 5 T
charge per pulse 1-2 4 nC
ion pulse length 005-100 - micros
containment time 20-2000 - ms
Parameters of CRYSIS Upper First EBIS IEL-1 build by Donets in 1968 lower Evolution of charge state distribution of nitrogen ions at Ee=545 keV
17 cm
CRYogenic Stockholm Ion Source
Imperial College London 22
Electron Beam Ion Source
Ion current extracted from an EBIS as a function of the
charge state for Na ions (Ne gas was added)
Comparison of the extractable (electric)
current between ECR and EBIS
Total ion charge trapped in an EBIS as a function of confinement time for different electron beam currents
Imperial College London 23
Laser Ion Sources
Schematic drawing of the experimental set up of a laser ion source By the impact of the laser with the target a plasma is created which expands
in the drift chamber and then is accelerated in the extraction gap
Imperial College London 24
Laser Ion Sources
The different charge states of the plasma are separated by the drift longitudinally and reduce space charge in the acceleration gap
By interaction of the plasma electrons with the electric field of the laser pulse the electrons are heated This leads to a shift of the charge state distribution of the plasma ions towards higher charge states
Imperial College London 25
Laser Ion Sources
The available laser power density on the target (for fixed total laser power influenced by beam size on target) strongly influences the charge state distribution of the plasma
The different charge states of the plasma are separated by the drift longitudinally (higher charge states first) and reduce space charge in the acceleration gap
Imperial College London 26
Production of negatively charged ion beams
Three Types of H- Ion Sources are in use
bull Surface conversion sources
bull Volume production sources
bull Hybrid production sources
Conserving energy when forming a negative ion through direct electron attachment the excess energy has to be dissipated through a photon A + e = Amacr + But radiative Capture is rare (5bull10-22cm2 for H2)
Higher cross sections (~10-20cm2 for H2 and Ee gt10 eV) can be realized when the excess energy can be transferred to a third particle M + e = A + B + e and sometimes = A + Bmacr
Cs can be used as an electron donator but the ionisation energy of 39 eV is much higher than the 075 eV electron affinity of H- =gt Surface treatment
Even better are processes which excite a molecule to the edge of breakup (vibrationally excited 4ltnlt12) and then dissociated by a slow electron
Imperial College London 27
Production of negatively charged ion beams
anode
cathode
gasin let solenoid filter
extractore -gtHslow
-driver
e -gtHfast 2
Magnetic dipole fields can be used as filters
to create areas of different electron
temperatures
Cross sections for different production
and destruction mechanisms
Imperial College London 28
Sources using surface production
Schematic layout of the LANCE surface source using a filament driven gas discharge for plasma production and surface conversion on a Cs target for H- formation
Picture of the LANCE surface source
Imperial College London 29
Sources using volume productioncopperm agnetiso latorwater
plasm a-cham ber
plasm a-electrode
screening-e lectrode
electron-dum ping
solenoid bending-m agnet
soleniod
cathodeand
gasin let
filter-m agnet
grid
The small experimental H- source in Frankfurt used a hot cathode driven gas discharge dipole fields and a Pt surface
cover for the reduction of the dissociation of the H2 molecules
Imperial College London 30
Sources using hybrid production schemes
The RAL H- source uses a Penning discharge (dipole for plasma
production and to influence electron temperature) and Cs injection
The SNS H- source developed in Berkley uses RF to produce the plasma dipoles to influence the electron density and a Cs collar
Imperial College London 31
The extraction of particle beams
Imperial College London 32
The space charge limit and Child-Langmuirs law
Imperial College London 33
The space charge limit and Child-Langmuirs law
Imperial College London 34
External and internal fields in the extractor laminar flow and pierce angle
Imperial College London 35
External and internal fields in the extractor laminar flow and pierce angle
Imperial College London 36
The beam emittance the acceptance of the extraction system and the conservation of the phase space
Imperial College London 37
The beam emittance the acceptance of the extraction system and the conservation of the phase space
Imperial College London 38
The beam emittance the acceptance of the extraction system and the conservation of the phase space
Imperial College London 3
Electron sourcesOnly very little energy is necessary to free electrons from the bound state or the
Upper levels of the ldquoelectron gasrdquo in solids This can be done by
1) Thermionic emission
The heated electron must
have an energy higher than
the workfunction
2) Photoemission
The photon energy must
exceed the work function
3) Field emission
high external electric fields
alter the potential barrier
and allow electrons to be
extracted by the tunneleffect
Imperial College London 4
Current density as a function of Binding energy and temperature
Material A (eV) Temp (deg K) J (Acm2)
Tungsten 60 454 2500 03
Thoriated W 3 263 1900 116
Mixed oxides 001 1 1200 1
Caesium 162 181
Tantalum 60 338 2500 238
CsOW 0003 072 1000 035
Richardson-Dushman equation
curr
en
t
Diode characteristic
Temperature limited
Space charge limited
voltage
kTo
eTAJ
2
Imperial College London 5
Thermionic guns
Imperial College London 6
Field emission of electrons from surfaces
Fowler Nordheim
J emission current density (Acm2)B field-independent constant [AV2]E applied field (Vcm) work function (eV)
EeEBJ
51071086
2
Imperial College London 7
Field emission of electrons from surfaces
Single carbon nano tube (CNT) and CNT arrays for the production of high brightness electron beams
Field emitter arrays designed for the production of large panel plasma screens
Imperial College London 8
Photo effect
20 2
1vmEE
chfhE electronkinpot
lightlightphoton
free electrons
bound electrons
light
uv- lampzinc-plate
glass
f
photo cathodeLight ()
ring anode
+ -IpA
U (I=0) U
h
f
Imperial College London 9
Photo effect and laser sources
2390 Laser
Laser
r
QEPJ
Imperial College London 10
Photo effect and laser sources
DESY PITZ 2 source (LC XFEL)
Imperial College London 11
Production of high currents of single charge state ion beams
For efficient ion production the electron energy should be app 2-4 times the
ionization energy of the ion
The impact of electron with gaseous atoms is mostly used for the
production of ion beams
Imperial College London 12
Production of high currents of single charge state ion beams
A Townsend gas discharge using an avalanche effect is an very effective way to produce a high amount of ions Therefore the Paschen criteria has to be fulfilled To improve the gas
discharge and to enhance plasma confinement magnetic fields are used
Imperial College London 13
Penning sources
The Penning Ion Source or PIG source (Philips Ionization vacuum Gauge) invented by Penning in 1937 uses a a dipole field for plasma confinement
The strong magnetic dipole field gives high efficiency as electrons oscillate inside the hollow anode between the the two cathodes at each end
The Lifetime of the source limited by sputtering of the cathodes especially for highly charged heavy ion operation
Imperial College London 14
Magnetron sources
The Magnetron ion source which was first presented by Van Voorhis in 1934 uses a solenoidal magnetic field for plasma confinement The field of ~ 01 T is generated with an external solenoid surrounding the ion source The chamber wall serves as anode while the cathode provides electrons through thermionic emission The filament mounted parallel to the magnetic field forces the electrons to spiral As with Penning sources the Lifetime of the source limited by sputtering of the cathodes especially for highly charged heavy ion operation
Imperial College London 15
Hot cathode sources
Filament Ion Source
Discharge in the plasma chamber is driven by the electrons delivered by the filament
1048774single charged ions up to 100 mA
bull Plasma enclosure by magnets
bull Pressure range 10-1 - 10-3 mbar
bull Discharge voltage 20 - 200 V (depending on ionization
voltage)bull Discharge current 10 - 500 A
100 m m
copperiso lator
w ater
steel
brass
m agnets
ground-electrode
screening-e lectrode
plasm a-electrode
B x
B z
C oSm -m agnets
gasin le tcathode
solenoid
filter-m agnet
Imperial College London 16
RF sources
Non resonant excitation of plasma by RF Only lower charge states available (low electron energy)
but high beam currents possible
Internal antenna to feed RF power into plasma =gt limited lifetime of antenna due to sputtering strong coupling of RF into plasma and good plasma confinement
Imperial College London 17
RF sources
Production of large ion currents (Igt1 A) of single charged ions for surface
treatment or plasma heating (tokamaks) Multiaperture extraction therefore difficult to feed beam into conventional accelerator structure
External antenna to feed RF power into plasma =gt Long lifetime of antenna but chamber has to be of non conducting material
Imperial College London 18
Production of high charge state ions
The PLASMA created is increased in density by electron
bombardment The maximum charge state that will be obtained depends on the incident electron energy
e + X = X+ + 2e
For multi-charge states
e + X i+ = X (i+1)+ + 2e
higher electron energies are required since electrons have to be removed from inner shells The maximum charge state is limited by the incident electron
energy
Imperial College London 19
Electron Cyclotron Resonance Sourcehf = cyc = (em) B
Radial and axial magnetic field distribution for the confinement of the source plasma
Only at the centre of the source the cyclotron condition for the electrons is full filled
(01-1 kW)
Extracted ion currents for different charge states of Argon
Imperial College London 20
Electron Cyclotron Resonance source
By variation of the longitudinal enclosing magnetic mirror configuration the
charge distribution can be influenced
Schematic layout of an ECR source for the production of radioactive
ion beams
Imperial College London 21
Electron Beam Ion Source
nominal valuesmax
valuesunits
electron beam current 350 1300 mA
electron beam energy 20 275 keV
trap length 12 - m
magnetic field 15 5 T
charge per pulse 1-2 4 nC
ion pulse length 005-100 - micros
containment time 20-2000 - ms
Parameters of CRYSIS Upper First EBIS IEL-1 build by Donets in 1968 lower Evolution of charge state distribution of nitrogen ions at Ee=545 keV
17 cm
CRYogenic Stockholm Ion Source
Imperial College London 22
Electron Beam Ion Source
Ion current extracted from an EBIS as a function of the
charge state for Na ions (Ne gas was added)
Comparison of the extractable (electric)
current between ECR and EBIS
Total ion charge trapped in an EBIS as a function of confinement time for different electron beam currents
Imperial College London 23
Laser Ion Sources
Schematic drawing of the experimental set up of a laser ion source By the impact of the laser with the target a plasma is created which expands
in the drift chamber and then is accelerated in the extraction gap
Imperial College London 24
Laser Ion Sources
The different charge states of the plasma are separated by the drift longitudinally and reduce space charge in the acceleration gap
By interaction of the plasma electrons with the electric field of the laser pulse the electrons are heated This leads to a shift of the charge state distribution of the plasma ions towards higher charge states
Imperial College London 25
Laser Ion Sources
The available laser power density on the target (for fixed total laser power influenced by beam size on target) strongly influences the charge state distribution of the plasma
The different charge states of the plasma are separated by the drift longitudinally (higher charge states first) and reduce space charge in the acceleration gap
Imperial College London 26
Production of negatively charged ion beams
Three Types of H- Ion Sources are in use
bull Surface conversion sources
bull Volume production sources
bull Hybrid production sources
Conserving energy when forming a negative ion through direct electron attachment the excess energy has to be dissipated through a photon A + e = Amacr + But radiative Capture is rare (5bull10-22cm2 for H2)
Higher cross sections (~10-20cm2 for H2 and Ee gt10 eV) can be realized when the excess energy can be transferred to a third particle M + e = A + B + e and sometimes = A + Bmacr
Cs can be used as an electron donator but the ionisation energy of 39 eV is much higher than the 075 eV electron affinity of H- =gt Surface treatment
Even better are processes which excite a molecule to the edge of breakup (vibrationally excited 4ltnlt12) and then dissociated by a slow electron
Imperial College London 27
Production of negatively charged ion beams
anode
cathode
gasin let solenoid filter
extractore -gtHslow
-driver
e -gtHfast 2
Magnetic dipole fields can be used as filters
to create areas of different electron
temperatures
Cross sections for different production
and destruction mechanisms
Imperial College London 28
Sources using surface production
Schematic layout of the LANCE surface source using a filament driven gas discharge for plasma production and surface conversion on a Cs target for H- formation
Picture of the LANCE surface source
Imperial College London 29
Sources using volume productioncopperm agnetiso latorwater
plasm a-cham ber
plasm a-electrode
screening-e lectrode
electron-dum ping
solenoid bending-m agnet
soleniod
cathodeand
gasin let
filter-m agnet
grid
The small experimental H- source in Frankfurt used a hot cathode driven gas discharge dipole fields and a Pt surface
cover for the reduction of the dissociation of the H2 molecules
Imperial College London 30
Sources using hybrid production schemes
The RAL H- source uses a Penning discharge (dipole for plasma
production and to influence electron temperature) and Cs injection
The SNS H- source developed in Berkley uses RF to produce the plasma dipoles to influence the electron density and a Cs collar
Imperial College London 31
The extraction of particle beams
Imperial College London 32
The space charge limit and Child-Langmuirs law
Imperial College London 33
The space charge limit and Child-Langmuirs law
Imperial College London 34
External and internal fields in the extractor laminar flow and pierce angle
Imperial College London 35
External and internal fields in the extractor laminar flow and pierce angle
Imperial College London 36
The beam emittance the acceptance of the extraction system and the conservation of the phase space
Imperial College London 37
The beam emittance the acceptance of the extraction system and the conservation of the phase space
Imperial College London 38
The beam emittance the acceptance of the extraction system and the conservation of the phase space
Imperial College London 4
Current density as a function of Binding energy and temperature
Material A (eV) Temp (deg K) J (Acm2)
Tungsten 60 454 2500 03
Thoriated W 3 263 1900 116
Mixed oxides 001 1 1200 1
Caesium 162 181
Tantalum 60 338 2500 238
CsOW 0003 072 1000 035
Richardson-Dushman equation
curr
en
t
Diode characteristic
Temperature limited
Space charge limited
voltage
kTo
eTAJ
2
Imperial College London 5
Thermionic guns
Imperial College London 6
Field emission of electrons from surfaces
Fowler Nordheim
J emission current density (Acm2)B field-independent constant [AV2]E applied field (Vcm) work function (eV)
EeEBJ
51071086
2
Imperial College London 7
Field emission of electrons from surfaces
Single carbon nano tube (CNT) and CNT arrays for the production of high brightness electron beams
Field emitter arrays designed for the production of large panel plasma screens
Imperial College London 8
Photo effect
20 2
1vmEE
chfhE electronkinpot
lightlightphoton
free electrons
bound electrons
light
uv- lampzinc-plate
glass
f
photo cathodeLight ()
ring anode
+ -IpA
U (I=0) U
h
f
Imperial College London 9
Photo effect and laser sources
2390 Laser
Laser
r
QEPJ
Imperial College London 10
Photo effect and laser sources
DESY PITZ 2 source (LC XFEL)
Imperial College London 11
Production of high currents of single charge state ion beams
For efficient ion production the electron energy should be app 2-4 times the
ionization energy of the ion
The impact of electron with gaseous atoms is mostly used for the
production of ion beams
Imperial College London 12
Production of high currents of single charge state ion beams
A Townsend gas discharge using an avalanche effect is an very effective way to produce a high amount of ions Therefore the Paschen criteria has to be fulfilled To improve the gas
discharge and to enhance plasma confinement magnetic fields are used
Imperial College London 13
Penning sources
The Penning Ion Source or PIG source (Philips Ionization vacuum Gauge) invented by Penning in 1937 uses a a dipole field for plasma confinement
The strong magnetic dipole field gives high efficiency as electrons oscillate inside the hollow anode between the the two cathodes at each end
The Lifetime of the source limited by sputtering of the cathodes especially for highly charged heavy ion operation
Imperial College London 14
Magnetron sources
The Magnetron ion source which was first presented by Van Voorhis in 1934 uses a solenoidal magnetic field for plasma confinement The field of ~ 01 T is generated with an external solenoid surrounding the ion source The chamber wall serves as anode while the cathode provides electrons through thermionic emission The filament mounted parallel to the magnetic field forces the electrons to spiral As with Penning sources the Lifetime of the source limited by sputtering of the cathodes especially for highly charged heavy ion operation
Imperial College London 15
Hot cathode sources
Filament Ion Source
Discharge in the plasma chamber is driven by the electrons delivered by the filament
1048774single charged ions up to 100 mA
bull Plasma enclosure by magnets
bull Pressure range 10-1 - 10-3 mbar
bull Discharge voltage 20 - 200 V (depending on ionization
voltage)bull Discharge current 10 - 500 A
100 m m
copperiso lator
w ater
steel
brass
m agnets
ground-electrode
screening-e lectrode
plasm a-electrode
B x
B z
C oSm -m agnets
gasin le tcathode
solenoid
filter-m agnet
Imperial College London 16
RF sources
Non resonant excitation of plasma by RF Only lower charge states available (low electron energy)
but high beam currents possible
Internal antenna to feed RF power into plasma =gt limited lifetime of antenna due to sputtering strong coupling of RF into plasma and good plasma confinement
Imperial College London 17
RF sources
Production of large ion currents (Igt1 A) of single charged ions for surface
treatment or plasma heating (tokamaks) Multiaperture extraction therefore difficult to feed beam into conventional accelerator structure
External antenna to feed RF power into plasma =gt Long lifetime of antenna but chamber has to be of non conducting material
Imperial College London 18
Production of high charge state ions
The PLASMA created is increased in density by electron
bombardment The maximum charge state that will be obtained depends on the incident electron energy
e + X = X+ + 2e
For multi-charge states
e + X i+ = X (i+1)+ + 2e
higher electron energies are required since electrons have to be removed from inner shells The maximum charge state is limited by the incident electron
energy
Imperial College London 19
Electron Cyclotron Resonance Sourcehf = cyc = (em) B
Radial and axial magnetic field distribution for the confinement of the source plasma
Only at the centre of the source the cyclotron condition for the electrons is full filled
(01-1 kW)
Extracted ion currents for different charge states of Argon
Imperial College London 20
Electron Cyclotron Resonance source
By variation of the longitudinal enclosing magnetic mirror configuration the
charge distribution can be influenced
Schematic layout of an ECR source for the production of radioactive
ion beams
Imperial College London 21
Electron Beam Ion Source
nominal valuesmax
valuesunits
electron beam current 350 1300 mA
electron beam energy 20 275 keV
trap length 12 - m
magnetic field 15 5 T
charge per pulse 1-2 4 nC
ion pulse length 005-100 - micros
containment time 20-2000 - ms
Parameters of CRYSIS Upper First EBIS IEL-1 build by Donets in 1968 lower Evolution of charge state distribution of nitrogen ions at Ee=545 keV
17 cm
CRYogenic Stockholm Ion Source
Imperial College London 22
Electron Beam Ion Source
Ion current extracted from an EBIS as a function of the
charge state for Na ions (Ne gas was added)
Comparison of the extractable (electric)
current between ECR and EBIS
Total ion charge trapped in an EBIS as a function of confinement time for different electron beam currents
Imperial College London 23
Laser Ion Sources
Schematic drawing of the experimental set up of a laser ion source By the impact of the laser with the target a plasma is created which expands
in the drift chamber and then is accelerated in the extraction gap
Imperial College London 24
Laser Ion Sources
The different charge states of the plasma are separated by the drift longitudinally and reduce space charge in the acceleration gap
By interaction of the plasma electrons with the electric field of the laser pulse the electrons are heated This leads to a shift of the charge state distribution of the plasma ions towards higher charge states
Imperial College London 25
Laser Ion Sources
The available laser power density on the target (for fixed total laser power influenced by beam size on target) strongly influences the charge state distribution of the plasma
The different charge states of the plasma are separated by the drift longitudinally (higher charge states first) and reduce space charge in the acceleration gap
Imperial College London 26
Production of negatively charged ion beams
Three Types of H- Ion Sources are in use
bull Surface conversion sources
bull Volume production sources
bull Hybrid production sources
Conserving energy when forming a negative ion through direct electron attachment the excess energy has to be dissipated through a photon A + e = Amacr + But radiative Capture is rare (5bull10-22cm2 for H2)
Higher cross sections (~10-20cm2 for H2 and Ee gt10 eV) can be realized when the excess energy can be transferred to a third particle M + e = A + B + e and sometimes = A + Bmacr
Cs can be used as an electron donator but the ionisation energy of 39 eV is much higher than the 075 eV electron affinity of H- =gt Surface treatment
Even better are processes which excite a molecule to the edge of breakup (vibrationally excited 4ltnlt12) and then dissociated by a slow electron
Imperial College London 27
Production of negatively charged ion beams
anode
cathode
gasin let solenoid filter
extractore -gtHslow
-driver
e -gtHfast 2
Magnetic dipole fields can be used as filters
to create areas of different electron
temperatures
Cross sections for different production
and destruction mechanisms
Imperial College London 28
Sources using surface production
Schematic layout of the LANCE surface source using a filament driven gas discharge for plasma production and surface conversion on a Cs target for H- formation
Picture of the LANCE surface source
Imperial College London 29
Sources using volume productioncopperm agnetiso latorwater
plasm a-cham ber
plasm a-electrode
screening-e lectrode
electron-dum ping
solenoid bending-m agnet
soleniod
cathodeand
gasin let
filter-m agnet
grid
The small experimental H- source in Frankfurt used a hot cathode driven gas discharge dipole fields and a Pt surface
cover for the reduction of the dissociation of the H2 molecules
Imperial College London 30
Sources using hybrid production schemes
The RAL H- source uses a Penning discharge (dipole for plasma
production and to influence electron temperature) and Cs injection
The SNS H- source developed in Berkley uses RF to produce the plasma dipoles to influence the electron density and a Cs collar
Imperial College London 31
The extraction of particle beams
Imperial College London 32
The space charge limit and Child-Langmuirs law
Imperial College London 33
The space charge limit and Child-Langmuirs law
Imperial College London 34
External and internal fields in the extractor laminar flow and pierce angle
Imperial College London 35
External and internal fields in the extractor laminar flow and pierce angle
Imperial College London 36
The beam emittance the acceptance of the extraction system and the conservation of the phase space
Imperial College London 37
The beam emittance the acceptance of the extraction system and the conservation of the phase space
Imperial College London 38
The beam emittance the acceptance of the extraction system and the conservation of the phase space
Imperial College London 5
Thermionic guns
Imperial College London 6
Field emission of electrons from surfaces
Fowler Nordheim
J emission current density (Acm2)B field-independent constant [AV2]E applied field (Vcm) work function (eV)
EeEBJ
51071086
2
Imperial College London 7
Field emission of electrons from surfaces
Single carbon nano tube (CNT) and CNT arrays for the production of high brightness electron beams
Field emitter arrays designed for the production of large panel plasma screens
Imperial College London 8
Photo effect
20 2
1vmEE
chfhE electronkinpot
lightlightphoton
free electrons
bound electrons
light
uv- lampzinc-plate
glass
f
photo cathodeLight ()
ring anode
+ -IpA
U (I=0) U
h
f
Imperial College London 9
Photo effect and laser sources
2390 Laser
Laser
r
QEPJ
Imperial College London 10
Photo effect and laser sources
DESY PITZ 2 source (LC XFEL)
Imperial College London 11
Production of high currents of single charge state ion beams
For efficient ion production the electron energy should be app 2-4 times the
ionization energy of the ion
The impact of electron with gaseous atoms is mostly used for the
production of ion beams
Imperial College London 12
Production of high currents of single charge state ion beams
A Townsend gas discharge using an avalanche effect is an very effective way to produce a high amount of ions Therefore the Paschen criteria has to be fulfilled To improve the gas
discharge and to enhance plasma confinement magnetic fields are used
Imperial College London 13
Penning sources
The Penning Ion Source or PIG source (Philips Ionization vacuum Gauge) invented by Penning in 1937 uses a a dipole field for plasma confinement
The strong magnetic dipole field gives high efficiency as electrons oscillate inside the hollow anode between the the two cathodes at each end
The Lifetime of the source limited by sputtering of the cathodes especially for highly charged heavy ion operation
Imperial College London 14
Magnetron sources
The Magnetron ion source which was first presented by Van Voorhis in 1934 uses a solenoidal magnetic field for plasma confinement The field of ~ 01 T is generated with an external solenoid surrounding the ion source The chamber wall serves as anode while the cathode provides electrons through thermionic emission The filament mounted parallel to the magnetic field forces the electrons to spiral As with Penning sources the Lifetime of the source limited by sputtering of the cathodes especially for highly charged heavy ion operation
Imperial College London 15
Hot cathode sources
Filament Ion Source
Discharge in the plasma chamber is driven by the electrons delivered by the filament
1048774single charged ions up to 100 mA
bull Plasma enclosure by magnets
bull Pressure range 10-1 - 10-3 mbar
bull Discharge voltage 20 - 200 V (depending on ionization
voltage)bull Discharge current 10 - 500 A
100 m m
copperiso lator
w ater
steel
brass
m agnets
ground-electrode
screening-e lectrode
plasm a-electrode
B x
B z
C oSm -m agnets
gasin le tcathode
solenoid
filter-m agnet
Imperial College London 16
RF sources
Non resonant excitation of plasma by RF Only lower charge states available (low electron energy)
but high beam currents possible
Internal antenna to feed RF power into plasma =gt limited lifetime of antenna due to sputtering strong coupling of RF into plasma and good plasma confinement
Imperial College London 17
RF sources
Production of large ion currents (Igt1 A) of single charged ions for surface
treatment or plasma heating (tokamaks) Multiaperture extraction therefore difficult to feed beam into conventional accelerator structure
External antenna to feed RF power into plasma =gt Long lifetime of antenna but chamber has to be of non conducting material
Imperial College London 18
Production of high charge state ions
The PLASMA created is increased in density by electron
bombardment The maximum charge state that will be obtained depends on the incident electron energy
e + X = X+ + 2e
For multi-charge states
e + X i+ = X (i+1)+ + 2e
higher electron energies are required since electrons have to be removed from inner shells The maximum charge state is limited by the incident electron
energy
Imperial College London 19
Electron Cyclotron Resonance Sourcehf = cyc = (em) B
Radial and axial magnetic field distribution for the confinement of the source plasma
Only at the centre of the source the cyclotron condition for the electrons is full filled
(01-1 kW)
Extracted ion currents for different charge states of Argon
Imperial College London 20
Electron Cyclotron Resonance source
By variation of the longitudinal enclosing magnetic mirror configuration the
charge distribution can be influenced
Schematic layout of an ECR source for the production of radioactive
ion beams
Imperial College London 21
Electron Beam Ion Source
nominal valuesmax
valuesunits
electron beam current 350 1300 mA
electron beam energy 20 275 keV
trap length 12 - m
magnetic field 15 5 T
charge per pulse 1-2 4 nC
ion pulse length 005-100 - micros
containment time 20-2000 - ms
Parameters of CRYSIS Upper First EBIS IEL-1 build by Donets in 1968 lower Evolution of charge state distribution of nitrogen ions at Ee=545 keV
17 cm
CRYogenic Stockholm Ion Source
Imperial College London 22
Electron Beam Ion Source
Ion current extracted from an EBIS as a function of the
charge state for Na ions (Ne gas was added)
Comparison of the extractable (electric)
current between ECR and EBIS
Total ion charge trapped in an EBIS as a function of confinement time for different electron beam currents
Imperial College London 23
Laser Ion Sources
Schematic drawing of the experimental set up of a laser ion source By the impact of the laser with the target a plasma is created which expands
in the drift chamber and then is accelerated in the extraction gap
Imperial College London 24
Laser Ion Sources
The different charge states of the plasma are separated by the drift longitudinally and reduce space charge in the acceleration gap
By interaction of the plasma electrons with the electric field of the laser pulse the electrons are heated This leads to a shift of the charge state distribution of the plasma ions towards higher charge states
Imperial College London 25
Laser Ion Sources
The available laser power density on the target (for fixed total laser power influenced by beam size on target) strongly influences the charge state distribution of the plasma
The different charge states of the plasma are separated by the drift longitudinally (higher charge states first) and reduce space charge in the acceleration gap
Imperial College London 26
Production of negatively charged ion beams
Three Types of H- Ion Sources are in use
bull Surface conversion sources
bull Volume production sources
bull Hybrid production sources
Conserving energy when forming a negative ion through direct electron attachment the excess energy has to be dissipated through a photon A + e = Amacr + But radiative Capture is rare (5bull10-22cm2 for H2)
Higher cross sections (~10-20cm2 for H2 and Ee gt10 eV) can be realized when the excess energy can be transferred to a third particle M + e = A + B + e and sometimes = A + Bmacr
Cs can be used as an electron donator but the ionisation energy of 39 eV is much higher than the 075 eV electron affinity of H- =gt Surface treatment
Even better are processes which excite a molecule to the edge of breakup (vibrationally excited 4ltnlt12) and then dissociated by a slow electron
Imperial College London 27
Production of negatively charged ion beams
anode
cathode
gasin let solenoid filter
extractore -gtHslow
-driver
e -gtHfast 2
Magnetic dipole fields can be used as filters
to create areas of different electron
temperatures
Cross sections for different production
and destruction mechanisms
Imperial College London 28
Sources using surface production
Schematic layout of the LANCE surface source using a filament driven gas discharge for plasma production and surface conversion on a Cs target for H- formation
Picture of the LANCE surface source
Imperial College London 29
Sources using volume productioncopperm agnetiso latorwater
plasm a-cham ber
plasm a-electrode
screening-e lectrode
electron-dum ping
solenoid bending-m agnet
soleniod
cathodeand
gasin let
filter-m agnet
grid
The small experimental H- source in Frankfurt used a hot cathode driven gas discharge dipole fields and a Pt surface
cover for the reduction of the dissociation of the H2 molecules
Imperial College London 30
Sources using hybrid production schemes
The RAL H- source uses a Penning discharge (dipole for plasma
production and to influence electron temperature) and Cs injection
The SNS H- source developed in Berkley uses RF to produce the plasma dipoles to influence the electron density and a Cs collar
Imperial College London 31
The extraction of particle beams
Imperial College London 32
The space charge limit and Child-Langmuirs law
Imperial College London 33
The space charge limit and Child-Langmuirs law
Imperial College London 34
External and internal fields in the extractor laminar flow and pierce angle
Imperial College London 35
External and internal fields in the extractor laminar flow and pierce angle
Imperial College London 36
The beam emittance the acceptance of the extraction system and the conservation of the phase space
Imperial College London 37
The beam emittance the acceptance of the extraction system and the conservation of the phase space
Imperial College London 38
The beam emittance the acceptance of the extraction system and the conservation of the phase space
Imperial College London 6
Field emission of electrons from surfaces
Fowler Nordheim
J emission current density (Acm2)B field-independent constant [AV2]E applied field (Vcm) work function (eV)
EeEBJ
51071086
2
Imperial College London 7
Field emission of electrons from surfaces
Single carbon nano tube (CNT) and CNT arrays for the production of high brightness electron beams
Field emitter arrays designed for the production of large panel plasma screens
Imperial College London 8
Photo effect
20 2
1vmEE
chfhE electronkinpot
lightlightphoton
free electrons
bound electrons
light
uv- lampzinc-plate
glass
f
photo cathodeLight ()
ring anode
+ -IpA
U (I=0) U
h
f
Imperial College London 9
Photo effect and laser sources
2390 Laser
Laser
r
QEPJ
Imperial College London 10
Photo effect and laser sources
DESY PITZ 2 source (LC XFEL)
Imperial College London 11
Production of high currents of single charge state ion beams
For efficient ion production the electron energy should be app 2-4 times the
ionization energy of the ion
The impact of electron with gaseous atoms is mostly used for the
production of ion beams
Imperial College London 12
Production of high currents of single charge state ion beams
A Townsend gas discharge using an avalanche effect is an very effective way to produce a high amount of ions Therefore the Paschen criteria has to be fulfilled To improve the gas
discharge and to enhance plasma confinement magnetic fields are used
Imperial College London 13
Penning sources
The Penning Ion Source or PIG source (Philips Ionization vacuum Gauge) invented by Penning in 1937 uses a a dipole field for plasma confinement
The strong magnetic dipole field gives high efficiency as electrons oscillate inside the hollow anode between the the two cathodes at each end
The Lifetime of the source limited by sputtering of the cathodes especially for highly charged heavy ion operation
Imperial College London 14
Magnetron sources
The Magnetron ion source which was first presented by Van Voorhis in 1934 uses a solenoidal magnetic field for plasma confinement The field of ~ 01 T is generated with an external solenoid surrounding the ion source The chamber wall serves as anode while the cathode provides electrons through thermionic emission The filament mounted parallel to the magnetic field forces the electrons to spiral As with Penning sources the Lifetime of the source limited by sputtering of the cathodes especially for highly charged heavy ion operation
Imperial College London 15
Hot cathode sources
Filament Ion Source
Discharge in the plasma chamber is driven by the electrons delivered by the filament
1048774single charged ions up to 100 mA
bull Plasma enclosure by magnets
bull Pressure range 10-1 - 10-3 mbar
bull Discharge voltage 20 - 200 V (depending on ionization
voltage)bull Discharge current 10 - 500 A
100 m m
copperiso lator
w ater
steel
brass
m agnets
ground-electrode
screening-e lectrode
plasm a-electrode
B x
B z
C oSm -m agnets
gasin le tcathode
solenoid
filter-m agnet
Imperial College London 16
RF sources
Non resonant excitation of plasma by RF Only lower charge states available (low electron energy)
but high beam currents possible
Internal antenna to feed RF power into plasma =gt limited lifetime of antenna due to sputtering strong coupling of RF into plasma and good plasma confinement
Imperial College London 17
RF sources
Production of large ion currents (Igt1 A) of single charged ions for surface
treatment or plasma heating (tokamaks) Multiaperture extraction therefore difficult to feed beam into conventional accelerator structure
External antenna to feed RF power into plasma =gt Long lifetime of antenna but chamber has to be of non conducting material
Imperial College London 18
Production of high charge state ions
The PLASMA created is increased in density by electron
bombardment The maximum charge state that will be obtained depends on the incident electron energy
e + X = X+ + 2e
For multi-charge states
e + X i+ = X (i+1)+ + 2e
higher electron energies are required since electrons have to be removed from inner shells The maximum charge state is limited by the incident electron
energy
Imperial College London 19
Electron Cyclotron Resonance Sourcehf = cyc = (em) B
Radial and axial magnetic field distribution for the confinement of the source plasma
Only at the centre of the source the cyclotron condition for the electrons is full filled
(01-1 kW)
Extracted ion currents for different charge states of Argon
Imperial College London 20
Electron Cyclotron Resonance source
By variation of the longitudinal enclosing magnetic mirror configuration the
charge distribution can be influenced
Schematic layout of an ECR source for the production of radioactive
ion beams
Imperial College London 21
Electron Beam Ion Source
nominal valuesmax
valuesunits
electron beam current 350 1300 mA
electron beam energy 20 275 keV
trap length 12 - m
magnetic field 15 5 T
charge per pulse 1-2 4 nC
ion pulse length 005-100 - micros
containment time 20-2000 - ms
Parameters of CRYSIS Upper First EBIS IEL-1 build by Donets in 1968 lower Evolution of charge state distribution of nitrogen ions at Ee=545 keV
17 cm
CRYogenic Stockholm Ion Source
Imperial College London 22
Electron Beam Ion Source
Ion current extracted from an EBIS as a function of the
charge state for Na ions (Ne gas was added)
Comparison of the extractable (electric)
current between ECR and EBIS
Total ion charge trapped in an EBIS as a function of confinement time for different electron beam currents
Imperial College London 23
Laser Ion Sources
Schematic drawing of the experimental set up of a laser ion source By the impact of the laser with the target a plasma is created which expands
in the drift chamber and then is accelerated in the extraction gap
Imperial College London 24
Laser Ion Sources
The different charge states of the plasma are separated by the drift longitudinally and reduce space charge in the acceleration gap
By interaction of the plasma electrons with the electric field of the laser pulse the electrons are heated This leads to a shift of the charge state distribution of the plasma ions towards higher charge states
Imperial College London 25
Laser Ion Sources
The available laser power density on the target (for fixed total laser power influenced by beam size on target) strongly influences the charge state distribution of the plasma
The different charge states of the plasma are separated by the drift longitudinally (higher charge states first) and reduce space charge in the acceleration gap
Imperial College London 26
Production of negatively charged ion beams
Three Types of H- Ion Sources are in use
bull Surface conversion sources
bull Volume production sources
bull Hybrid production sources
Conserving energy when forming a negative ion through direct electron attachment the excess energy has to be dissipated through a photon A + e = Amacr + But radiative Capture is rare (5bull10-22cm2 for H2)
Higher cross sections (~10-20cm2 for H2 and Ee gt10 eV) can be realized when the excess energy can be transferred to a third particle M + e = A + B + e and sometimes = A + Bmacr
Cs can be used as an electron donator but the ionisation energy of 39 eV is much higher than the 075 eV electron affinity of H- =gt Surface treatment
Even better are processes which excite a molecule to the edge of breakup (vibrationally excited 4ltnlt12) and then dissociated by a slow electron
Imperial College London 27
Production of negatively charged ion beams
anode
cathode
gasin let solenoid filter
extractore -gtHslow
-driver
e -gtHfast 2
Magnetic dipole fields can be used as filters
to create areas of different electron
temperatures
Cross sections for different production
and destruction mechanisms
Imperial College London 28
Sources using surface production
Schematic layout of the LANCE surface source using a filament driven gas discharge for plasma production and surface conversion on a Cs target for H- formation
Picture of the LANCE surface source
Imperial College London 29
Sources using volume productioncopperm agnetiso latorwater
plasm a-cham ber
plasm a-electrode
screening-e lectrode
electron-dum ping
solenoid bending-m agnet
soleniod
cathodeand
gasin let
filter-m agnet
grid
The small experimental H- source in Frankfurt used a hot cathode driven gas discharge dipole fields and a Pt surface
cover for the reduction of the dissociation of the H2 molecules
Imperial College London 30
Sources using hybrid production schemes
The RAL H- source uses a Penning discharge (dipole for plasma
production and to influence electron temperature) and Cs injection
The SNS H- source developed in Berkley uses RF to produce the plasma dipoles to influence the electron density and a Cs collar
Imperial College London 31
The extraction of particle beams
Imperial College London 32
The space charge limit and Child-Langmuirs law
Imperial College London 33
The space charge limit and Child-Langmuirs law
Imperial College London 34
External and internal fields in the extractor laminar flow and pierce angle
Imperial College London 35
External and internal fields in the extractor laminar flow and pierce angle
Imperial College London 36
The beam emittance the acceptance of the extraction system and the conservation of the phase space
Imperial College London 37
The beam emittance the acceptance of the extraction system and the conservation of the phase space
Imperial College London 38
The beam emittance the acceptance of the extraction system and the conservation of the phase space
Imperial College London 7
Field emission of electrons from surfaces
Single carbon nano tube (CNT) and CNT arrays for the production of high brightness electron beams
Field emitter arrays designed for the production of large panel plasma screens
Imperial College London 8
Photo effect
20 2
1vmEE
chfhE electronkinpot
lightlightphoton
free electrons
bound electrons
light
uv- lampzinc-plate
glass
f
photo cathodeLight ()
ring anode
+ -IpA
U (I=0) U
h
f
Imperial College London 9
Photo effect and laser sources
2390 Laser
Laser
r
QEPJ
Imperial College London 10
Photo effect and laser sources
DESY PITZ 2 source (LC XFEL)
Imperial College London 11
Production of high currents of single charge state ion beams
For efficient ion production the electron energy should be app 2-4 times the
ionization energy of the ion
The impact of electron with gaseous atoms is mostly used for the
production of ion beams
Imperial College London 12
Production of high currents of single charge state ion beams
A Townsend gas discharge using an avalanche effect is an very effective way to produce a high amount of ions Therefore the Paschen criteria has to be fulfilled To improve the gas
discharge and to enhance plasma confinement magnetic fields are used
Imperial College London 13
Penning sources
The Penning Ion Source or PIG source (Philips Ionization vacuum Gauge) invented by Penning in 1937 uses a a dipole field for plasma confinement
The strong magnetic dipole field gives high efficiency as electrons oscillate inside the hollow anode between the the two cathodes at each end
The Lifetime of the source limited by sputtering of the cathodes especially for highly charged heavy ion operation
Imperial College London 14
Magnetron sources
The Magnetron ion source which was first presented by Van Voorhis in 1934 uses a solenoidal magnetic field for plasma confinement The field of ~ 01 T is generated with an external solenoid surrounding the ion source The chamber wall serves as anode while the cathode provides electrons through thermionic emission The filament mounted parallel to the magnetic field forces the electrons to spiral As with Penning sources the Lifetime of the source limited by sputtering of the cathodes especially for highly charged heavy ion operation
Imperial College London 15
Hot cathode sources
Filament Ion Source
Discharge in the plasma chamber is driven by the electrons delivered by the filament
1048774single charged ions up to 100 mA
bull Plasma enclosure by magnets
bull Pressure range 10-1 - 10-3 mbar
bull Discharge voltage 20 - 200 V (depending on ionization
voltage)bull Discharge current 10 - 500 A
100 m m
copperiso lator
w ater
steel
brass
m agnets
ground-electrode
screening-e lectrode
plasm a-electrode
B x
B z
C oSm -m agnets
gasin le tcathode
solenoid
filter-m agnet
Imperial College London 16
RF sources
Non resonant excitation of plasma by RF Only lower charge states available (low electron energy)
but high beam currents possible
Internal antenna to feed RF power into plasma =gt limited lifetime of antenna due to sputtering strong coupling of RF into plasma and good plasma confinement
Imperial College London 17
RF sources
Production of large ion currents (Igt1 A) of single charged ions for surface
treatment or plasma heating (tokamaks) Multiaperture extraction therefore difficult to feed beam into conventional accelerator structure
External antenna to feed RF power into plasma =gt Long lifetime of antenna but chamber has to be of non conducting material
Imperial College London 18
Production of high charge state ions
The PLASMA created is increased in density by electron
bombardment The maximum charge state that will be obtained depends on the incident electron energy
e + X = X+ + 2e
For multi-charge states
e + X i+ = X (i+1)+ + 2e
higher electron energies are required since electrons have to be removed from inner shells The maximum charge state is limited by the incident electron
energy
Imperial College London 19
Electron Cyclotron Resonance Sourcehf = cyc = (em) B
Radial and axial magnetic field distribution for the confinement of the source plasma
Only at the centre of the source the cyclotron condition for the electrons is full filled
(01-1 kW)
Extracted ion currents for different charge states of Argon
Imperial College London 20
Electron Cyclotron Resonance source
By variation of the longitudinal enclosing magnetic mirror configuration the
charge distribution can be influenced
Schematic layout of an ECR source for the production of radioactive
ion beams
Imperial College London 21
Electron Beam Ion Source
nominal valuesmax
valuesunits
electron beam current 350 1300 mA
electron beam energy 20 275 keV
trap length 12 - m
magnetic field 15 5 T
charge per pulse 1-2 4 nC
ion pulse length 005-100 - micros
containment time 20-2000 - ms
Parameters of CRYSIS Upper First EBIS IEL-1 build by Donets in 1968 lower Evolution of charge state distribution of nitrogen ions at Ee=545 keV
17 cm
CRYogenic Stockholm Ion Source
Imperial College London 22
Electron Beam Ion Source
Ion current extracted from an EBIS as a function of the
charge state for Na ions (Ne gas was added)
Comparison of the extractable (electric)
current between ECR and EBIS
Total ion charge trapped in an EBIS as a function of confinement time for different electron beam currents
Imperial College London 23
Laser Ion Sources
Schematic drawing of the experimental set up of a laser ion source By the impact of the laser with the target a plasma is created which expands
in the drift chamber and then is accelerated in the extraction gap
Imperial College London 24
Laser Ion Sources
The different charge states of the plasma are separated by the drift longitudinally and reduce space charge in the acceleration gap
By interaction of the plasma electrons with the electric field of the laser pulse the electrons are heated This leads to a shift of the charge state distribution of the plasma ions towards higher charge states
Imperial College London 25
Laser Ion Sources
The available laser power density on the target (for fixed total laser power influenced by beam size on target) strongly influences the charge state distribution of the plasma
The different charge states of the plasma are separated by the drift longitudinally (higher charge states first) and reduce space charge in the acceleration gap
Imperial College London 26
Production of negatively charged ion beams
Three Types of H- Ion Sources are in use
bull Surface conversion sources
bull Volume production sources
bull Hybrid production sources
Conserving energy when forming a negative ion through direct electron attachment the excess energy has to be dissipated through a photon A + e = Amacr + But radiative Capture is rare (5bull10-22cm2 for H2)
Higher cross sections (~10-20cm2 for H2 and Ee gt10 eV) can be realized when the excess energy can be transferred to a third particle M + e = A + B + e and sometimes = A + Bmacr
Cs can be used as an electron donator but the ionisation energy of 39 eV is much higher than the 075 eV electron affinity of H- =gt Surface treatment
Even better are processes which excite a molecule to the edge of breakup (vibrationally excited 4ltnlt12) and then dissociated by a slow electron
Imperial College London 27
Production of negatively charged ion beams
anode
cathode
gasin let solenoid filter
extractore -gtHslow
-driver
e -gtHfast 2
Magnetic dipole fields can be used as filters
to create areas of different electron
temperatures
Cross sections for different production
and destruction mechanisms
Imperial College London 28
Sources using surface production
Schematic layout of the LANCE surface source using a filament driven gas discharge for plasma production and surface conversion on a Cs target for H- formation
Picture of the LANCE surface source
Imperial College London 29
Sources using volume productioncopperm agnetiso latorwater
plasm a-cham ber
plasm a-electrode
screening-e lectrode
electron-dum ping
solenoid bending-m agnet
soleniod
cathodeand
gasin let
filter-m agnet
grid
The small experimental H- source in Frankfurt used a hot cathode driven gas discharge dipole fields and a Pt surface
cover for the reduction of the dissociation of the H2 molecules
Imperial College London 30
Sources using hybrid production schemes
The RAL H- source uses a Penning discharge (dipole for plasma
production and to influence electron temperature) and Cs injection
The SNS H- source developed in Berkley uses RF to produce the plasma dipoles to influence the electron density and a Cs collar
Imperial College London 31
The extraction of particle beams
Imperial College London 32
The space charge limit and Child-Langmuirs law
Imperial College London 33
The space charge limit and Child-Langmuirs law
Imperial College London 34
External and internal fields in the extractor laminar flow and pierce angle
Imperial College London 35
External and internal fields in the extractor laminar flow and pierce angle
Imperial College London 36
The beam emittance the acceptance of the extraction system and the conservation of the phase space
Imperial College London 37
The beam emittance the acceptance of the extraction system and the conservation of the phase space
Imperial College London 38
The beam emittance the acceptance of the extraction system and the conservation of the phase space
Imperial College London 8
Photo effect
20 2
1vmEE
chfhE electronkinpot
lightlightphoton
free electrons
bound electrons
light
uv- lampzinc-plate
glass
f
photo cathodeLight ()
ring anode
+ -IpA
U (I=0) U
h
f
Imperial College London 9
Photo effect and laser sources
2390 Laser
Laser
r
QEPJ
Imperial College London 10
Photo effect and laser sources
DESY PITZ 2 source (LC XFEL)
Imperial College London 11
Production of high currents of single charge state ion beams
For efficient ion production the electron energy should be app 2-4 times the
ionization energy of the ion
The impact of electron with gaseous atoms is mostly used for the
production of ion beams
Imperial College London 12
Production of high currents of single charge state ion beams
A Townsend gas discharge using an avalanche effect is an very effective way to produce a high amount of ions Therefore the Paschen criteria has to be fulfilled To improve the gas
discharge and to enhance plasma confinement magnetic fields are used
Imperial College London 13
Penning sources
The Penning Ion Source or PIG source (Philips Ionization vacuum Gauge) invented by Penning in 1937 uses a a dipole field for plasma confinement
The strong magnetic dipole field gives high efficiency as electrons oscillate inside the hollow anode between the the two cathodes at each end
The Lifetime of the source limited by sputtering of the cathodes especially for highly charged heavy ion operation
Imperial College London 14
Magnetron sources
The Magnetron ion source which was first presented by Van Voorhis in 1934 uses a solenoidal magnetic field for plasma confinement The field of ~ 01 T is generated with an external solenoid surrounding the ion source The chamber wall serves as anode while the cathode provides electrons through thermionic emission The filament mounted parallel to the magnetic field forces the electrons to spiral As with Penning sources the Lifetime of the source limited by sputtering of the cathodes especially for highly charged heavy ion operation
Imperial College London 15
Hot cathode sources
Filament Ion Source
Discharge in the plasma chamber is driven by the electrons delivered by the filament
1048774single charged ions up to 100 mA
bull Plasma enclosure by magnets
bull Pressure range 10-1 - 10-3 mbar
bull Discharge voltage 20 - 200 V (depending on ionization
voltage)bull Discharge current 10 - 500 A
100 m m
copperiso lator
w ater
steel
brass
m agnets
ground-electrode
screening-e lectrode
plasm a-electrode
B x
B z
C oSm -m agnets
gasin le tcathode
solenoid
filter-m agnet
Imperial College London 16
RF sources
Non resonant excitation of plasma by RF Only lower charge states available (low electron energy)
but high beam currents possible
Internal antenna to feed RF power into plasma =gt limited lifetime of antenna due to sputtering strong coupling of RF into plasma and good plasma confinement
Imperial College London 17
RF sources
Production of large ion currents (Igt1 A) of single charged ions for surface
treatment or plasma heating (tokamaks) Multiaperture extraction therefore difficult to feed beam into conventional accelerator structure
External antenna to feed RF power into plasma =gt Long lifetime of antenna but chamber has to be of non conducting material
Imperial College London 18
Production of high charge state ions
The PLASMA created is increased in density by electron
bombardment The maximum charge state that will be obtained depends on the incident electron energy
e + X = X+ + 2e
For multi-charge states
e + X i+ = X (i+1)+ + 2e
higher electron energies are required since electrons have to be removed from inner shells The maximum charge state is limited by the incident electron
energy
Imperial College London 19
Electron Cyclotron Resonance Sourcehf = cyc = (em) B
Radial and axial magnetic field distribution for the confinement of the source plasma
Only at the centre of the source the cyclotron condition for the electrons is full filled
(01-1 kW)
Extracted ion currents for different charge states of Argon
Imperial College London 20
Electron Cyclotron Resonance source
By variation of the longitudinal enclosing magnetic mirror configuration the
charge distribution can be influenced
Schematic layout of an ECR source for the production of radioactive
ion beams
Imperial College London 21
Electron Beam Ion Source
nominal valuesmax
valuesunits
electron beam current 350 1300 mA
electron beam energy 20 275 keV
trap length 12 - m
magnetic field 15 5 T
charge per pulse 1-2 4 nC
ion pulse length 005-100 - micros
containment time 20-2000 - ms
Parameters of CRYSIS Upper First EBIS IEL-1 build by Donets in 1968 lower Evolution of charge state distribution of nitrogen ions at Ee=545 keV
17 cm
CRYogenic Stockholm Ion Source
Imperial College London 22
Electron Beam Ion Source
Ion current extracted from an EBIS as a function of the
charge state for Na ions (Ne gas was added)
Comparison of the extractable (electric)
current between ECR and EBIS
Total ion charge trapped in an EBIS as a function of confinement time for different electron beam currents
Imperial College London 23
Laser Ion Sources
Schematic drawing of the experimental set up of a laser ion source By the impact of the laser with the target a plasma is created which expands
in the drift chamber and then is accelerated in the extraction gap
Imperial College London 24
Laser Ion Sources
The different charge states of the plasma are separated by the drift longitudinally and reduce space charge in the acceleration gap
By interaction of the plasma electrons with the electric field of the laser pulse the electrons are heated This leads to a shift of the charge state distribution of the plasma ions towards higher charge states
Imperial College London 25
Laser Ion Sources
The available laser power density on the target (for fixed total laser power influenced by beam size on target) strongly influences the charge state distribution of the plasma
The different charge states of the plasma are separated by the drift longitudinally (higher charge states first) and reduce space charge in the acceleration gap
Imperial College London 26
Production of negatively charged ion beams
Three Types of H- Ion Sources are in use
bull Surface conversion sources
bull Volume production sources
bull Hybrid production sources
Conserving energy when forming a negative ion through direct electron attachment the excess energy has to be dissipated through a photon A + e = Amacr + But radiative Capture is rare (5bull10-22cm2 for H2)
Higher cross sections (~10-20cm2 for H2 and Ee gt10 eV) can be realized when the excess energy can be transferred to a third particle M + e = A + B + e and sometimes = A + Bmacr
Cs can be used as an electron donator but the ionisation energy of 39 eV is much higher than the 075 eV electron affinity of H- =gt Surface treatment
Even better are processes which excite a molecule to the edge of breakup (vibrationally excited 4ltnlt12) and then dissociated by a slow electron
Imperial College London 27
Production of negatively charged ion beams
anode
cathode
gasin let solenoid filter
extractore -gtHslow
-driver
e -gtHfast 2
Magnetic dipole fields can be used as filters
to create areas of different electron
temperatures
Cross sections for different production
and destruction mechanisms
Imperial College London 28
Sources using surface production
Schematic layout of the LANCE surface source using a filament driven gas discharge for plasma production and surface conversion on a Cs target for H- formation
Picture of the LANCE surface source
Imperial College London 29
Sources using volume productioncopperm agnetiso latorwater
plasm a-cham ber
plasm a-electrode
screening-e lectrode
electron-dum ping
solenoid bending-m agnet
soleniod
cathodeand
gasin let
filter-m agnet
grid
The small experimental H- source in Frankfurt used a hot cathode driven gas discharge dipole fields and a Pt surface
cover for the reduction of the dissociation of the H2 molecules
Imperial College London 30
Sources using hybrid production schemes
The RAL H- source uses a Penning discharge (dipole for plasma
production and to influence electron temperature) and Cs injection
The SNS H- source developed in Berkley uses RF to produce the plasma dipoles to influence the electron density and a Cs collar
Imperial College London 31
The extraction of particle beams
Imperial College London 32
The space charge limit and Child-Langmuirs law
Imperial College London 33
The space charge limit and Child-Langmuirs law
Imperial College London 34
External and internal fields in the extractor laminar flow and pierce angle
Imperial College London 35
External and internal fields in the extractor laminar flow and pierce angle
Imperial College London 36
The beam emittance the acceptance of the extraction system and the conservation of the phase space
Imperial College London 37
The beam emittance the acceptance of the extraction system and the conservation of the phase space
Imperial College London 38
The beam emittance the acceptance of the extraction system and the conservation of the phase space
Imperial College London 9
Photo effect and laser sources
2390 Laser
Laser
r
QEPJ
Imperial College London 10
Photo effect and laser sources
DESY PITZ 2 source (LC XFEL)
Imperial College London 11
Production of high currents of single charge state ion beams
For efficient ion production the electron energy should be app 2-4 times the
ionization energy of the ion
The impact of electron with gaseous atoms is mostly used for the
production of ion beams
Imperial College London 12
Production of high currents of single charge state ion beams
A Townsend gas discharge using an avalanche effect is an very effective way to produce a high amount of ions Therefore the Paschen criteria has to be fulfilled To improve the gas
discharge and to enhance plasma confinement magnetic fields are used
Imperial College London 13
Penning sources
The Penning Ion Source or PIG source (Philips Ionization vacuum Gauge) invented by Penning in 1937 uses a a dipole field for plasma confinement
The strong magnetic dipole field gives high efficiency as electrons oscillate inside the hollow anode between the the two cathodes at each end
The Lifetime of the source limited by sputtering of the cathodes especially for highly charged heavy ion operation
Imperial College London 14
Magnetron sources
The Magnetron ion source which was first presented by Van Voorhis in 1934 uses a solenoidal magnetic field for plasma confinement The field of ~ 01 T is generated with an external solenoid surrounding the ion source The chamber wall serves as anode while the cathode provides electrons through thermionic emission The filament mounted parallel to the magnetic field forces the electrons to spiral As with Penning sources the Lifetime of the source limited by sputtering of the cathodes especially for highly charged heavy ion operation
Imperial College London 15
Hot cathode sources
Filament Ion Source
Discharge in the plasma chamber is driven by the electrons delivered by the filament
1048774single charged ions up to 100 mA
bull Plasma enclosure by magnets
bull Pressure range 10-1 - 10-3 mbar
bull Discharge voltage 20 - 200 V (depending on ionization
voltage)bull Discharge current 10 - 500 A
100 m m
copperiso lator
w ater
steel
brass
m agnets
ground-electrode
screening-e lectrode
plasm a-electrode
B x
B z
C oSm -m agnets
gasin le tcathode
solenoid
filter-m agnet
Imperial College London 16
RF sources
Non resonant excitation of plasma by RF Only lower charge states available (low electron energy)
but high beam currents possible
Internal antenna to feed RF power into plasma =gt limited lifetime of antenna due to sputtering strong coupling of RF into plasma and good plasma confinement
Imperial College London 17
RF sources
Production of large ion currents (Igt1 A) of single charged ions for surface
treatment or plasma heating (tokamaks) Multiaperture extraction therefore difficult to feed beam into conventional accelerator structure
External antenna to feed RF power into plasma =gt Long lifetime of antenna but chamber has to be of non conducting material
Imperial College London 18
Production of high charge state ions
The PLASMA created is increased in density by electron
bombardment The maximum charge state that will be obtained depends on the incident electron energy
e + X = X+ + 2e
For multi-charge states
e + X i+ = X (i+1)+ + 2e
higher electron energies are required since electrons have to be removed from inner shells The maximum charge state is limited by the incident electron
energy
Imperial College London 19
Electron Cyclotron Resonance Sourcehf = cyc = (em) B
Radial and axial magnetic field distribution for the confinement of the source plasma
Only at the centre of the source the cyclotron condition for the electrons is full filled
(01-1 kW)
Extracted ion currents for different charge states of Argon
Imperial College London 20
Electron Cyclotron Resonance source
By variation of the longitudinal enclosing magnetic mirror configuration the
charge distribution can be influenced
Schematic layout of an ECR source for the production of radioactive
ion beams
Imperial College London 21
Electron Beam Ion Source
nominal valuesmax
valuesunits
electron beam current 350 1300 mA
electron beam energy 20 275 keV
trap length 12 - m
magnetic field 15 5 T
charge per pulse 1-2 4 nC
ion pulse length 005-100 - micros
containment time 20-2000 - ms
Parameters of CRYSIS Upper First EBIS IEL-1 build by Donets in 1968 lower Evolution of charge state distribution of nitrogen ions at Ee=545 keV
17 cm
CRYogenic Stockholm Ion Source
Imperial College London 22
Electron Beam Ion Source
Ion current extracted from an EBIS as a function of the
charge state for Na ions (Ne gas was added)
Comparison of the extractable (electric)
current between ECR and EBIS
Total ion charge trapped in an EBIS as a function of confinement time for different electron beam currents
Imperial College London 23
Laser Ion Sources
Schematic drawing of the experimental set up of a laser ion source By the impact of the laser with the target a plasma is created which expands
in the drift chamber and then is accelerated in the extraction gap
Imperial College London 24
Laser Ion Sources
The different charge states of the plasma are separated by the drift longitudinally and reduce space charge in the acceleration gap
By interaction of the plasma electrons with the electric field of the laser pulse the electrons are heated This leads to a shift of the charge state distribution of the plasma ions towards higher charge states
Imperial College London 25
Laser Ion Sources
The available laser power density on the target (for fixed total laser power influenced by beam size on target) strongly influences the charge state distribution of the plasma
The different charge states of the plasma are separated by the drift longitudinally (higher charge states first) and reduce space charge in the acceleration gap
Imperial College London 26
Production of negatively charged ion beams
Three Types of H- Ion Sources are in use
bull Surface conversion sources
bull Volume production sources
bull Hybrid production sources
Conserving energy when forming a negative ion through direct electron attachment the excess energy has to be dissipated through a photon A + e = Amacr + But radiative Capture is rare (5bull10-22cm2 for H2)
Higher cross sections (~10-20cm2 for H2 and Ee gt10 eV) can be realized when the excess energy can be transferred to a third particle M + e = A + B + e and sometimes = A + Bmacr
Cs can be used as an electron donator but the ionisation energy of 39 eV is much higher than the 075 eV electron affinity of H- =gt Surface treatment
Even better are processes which excite a molecule to the edge of breakup (vibrationally excited 4ltnlt12) and then dissociated by a slow electron
Imperial College London 27
Production of negatively charged ion beams
anode
cathode
gasin let solenoid filter
extractore -gtHslow
-driver
e -gtHfast 2
Magnetic dipole fields can be used as filters
to create areas of different electron
temperatures
Cross sections for different production
and destruction mechanisms
Imperial College London 28
Sources using surface production
Schematic layout of the LANCE surface source using a filament driven gas discharge for plasma production and surface conversion on a Cs target for H- formation
Picture of the LANCE surface source
Imperial College London 29
Sources using volume productioncopperm agnetiso latorwater
plasm a-cham ber
plasm a-electrode
screening-e lectrode
electron-dum ping
solenoid bending-m agnet
soleniod
cathodeand
gasin let
filter-m agnet
grid
The small experimental H- source in Frankfurt used a hot cathode driven gas discharge dipole fields and a Pt surface
cover for the reduction of the dissociation of the H2 molecules
Imperial College London 30
Sources using hybrid production schemes
The RAL H- source uses a Penning discharge (dipole for plasma
production and to influence electron temperature) and Cs injection
The SNS H- source developed in Berkley uses RF to produce the plasma dipoles to influence the electron density and a Cs collar
Imperial College London 31
The extraction of particle beams
Imperial College London 32
The space charge limit and Child-Langmuirs law
Imperial College London 33
The space charge limit and Child-Langmuirs law
Imperial College London 34
External and internal fields in the extractor laminar flow and pierce angle
Imperial College London 35
External and internal fields in the extractor laminar flow and pierce angle
Imperial College London 36
The beam emittance the acceptance of the extraction system and the conservation of the phase space
Imperial College London 37
The beam emittance the acceptance of the extraction system and the conservation of the phase space
Imperial College London 38
The beam emittance the acceptance of the extraction system and the conservation of the phase space
Imperial College London 10
Photo effect and laser sources
DESY PITZ 2 source (LC XFEL)
Imperial College London 11
Production of high currents of single charge state ion beams
For efficient ion production the electron energy should be app 2-4 times the
ionization energy of the ion
The impact of electron with gaseous atoms is mostly used for the
production of ion beams
Imperial College London 12
Production of high currents of single charge state ion beams
A Townsend gas discharge using an avalanche effect is an very effective way to produce a high amount of ions Therefore the Paschen criteria has to be fulfilled To improve the gas
discharge and to enhance plasma confinement magnetic fields are used
Imperial College London 13
Penning sources
The Penning Ion Source or PIG source (Philips Ionization vacuum Gauge) invented by Penning in 1937 uses a a dipole field for plasma confinement
The strong magnetic dipole field gives high efficiency as electrons oscillate inside the hollow anode between the the two cathodes at each end
The Lifetime of the source limited by sputtering of the cathodes especially for highly charged heavy ion operation
Imperial College London 14
Magnetron sources
The Magnetron ion source which was first presented by Van Voorhis in 1934 uses a solenoidal magnetic field for plasma confinement The field of ~ 01 T is generated with an external solenoid surrounding the ion source The chamber wall serves as anode while the cathode provides electrons through thermionic emission The filament mounted parallel to the magnetic field forces the electrons to spiral As with Penning sources the Lifetime of the source limited by sputtering of the cathodes especially for highly charged heavy ion operation
Imperial College London 15
Hot cathode sources
Filament Ion Source
Discharge in the plasma chamber is driven by the electrons delivered by the filament
1048774single charged ions up to 100 mA
bull Plasma enclosure by magnets
bull Pressure range 10-1 - 10-3 mbar
bull Discharge voltage 20 - 200 V (depending on ionization
voltage)bull Discharge current 10 - 500 A
100 m m
copperiso lator
w ater
steel
brass
m agnets
ground-electrode
screening-e lectrode
plasm a-electrode
B x
B z
C oSm -m agnets
gasin le tcathode
solenoid
filter-m agnet
Imperial College London 16
RF sources
Non resonant excitation of plasma by RF Only lower charge states available (low electron energy)
but high beam currents possible
Internal antenna to feed RF power into plasma =gt limited lifetime of antenna due to sputtering strong coupling of RF into plasma and good plasma confinement
Imperial College London 17
RF sources
Production of large ion currents (Igt1 A) of single charged ions for surface
treatment or plasma heating (tokamaks) Multiaperture extraction therefore difficult to feed beam into conventional accelerator structure
External antenna to feed RF power into plasma =gt Long lifetime of antenna but chamber has to be of non conducting material
Imperial College London 18
Production of high charge state ions
The PLASMA created is increased in density by electron
bombardment The maximum charge state that will be obtained depends on the incident electron energy
e + X = X+ + 2e
For multi-charge states
e + X i+ = X (i+1)+ + 2e
higher electron energies are required since electrons have to be removed from inner shells The maximum charge state is limited by the incident electron
energy
Imperial College London 19
Electron Cyclotron Resonance Sourcehf = cyc = (em) B
Radial and axial magnetic field distribution for the confinement of the source plasma
Only at the centre of the source the cyclotron condition for the electrons is full filled
(01-1 kW)
Extracted ion currents for different charge states of Argon
Imperial College London 20
Electron Cyclotron Resonance source
By variation of the longitudinal enclosing magnetic mirror configuration the
charge distribution can be influenced
Schematic layout of an ECR source for the production of radioactive
ion beams
Imperial College London 21
Electron Beam Ion Source
nominal valuesmax
valuesunits
electron beam current 350 1300 mA
electron beam energy 20 275 keV
trap length 12 - m
magnetic field 15 5 T
charge per pulse 1-2 4 nC
ion pulse length 005-100 - micros
containment time 20-2000 - ms
Parameters of CRYSIS Upper First EBIS IEL-1 build by Donets in 1968 lower Evolution of charge state distribution of nitrogen ions at Ee=545 keV
17 cm
CRYogenic Stockholm Ion Source
Imperial College London 22
Electron Beam Ion Source
Ion current extracted from an EBIS as a function of the
charge state for Na ions (Ne gas was added)
Comparison of the extractable (electric)
current between ECR and EBIS
Total ion charge trapped in an EBIS as a function of confinement time for different electron beam currents
Imperial College London 23
Laser Ion Sources
Schematic drawing of the experimental set up of a laser ion source By the impact of the laser with the target a plasma is created which expands
in the drift chamber and then is accelerated in the extraction gap
Imperial College London 24
Laser Ion Sources
The different charge states of the plasma are separated by the drift longitudinally and reduce space charge in the acceleration gap
By interaction of the plasma electrons with the electric field of the laser pulse the electrons are heated This leads to a shift of the charge state distribution of the plasma ions towards higher charge states
Imperial College London 25
Laser Ion Sources
The available laser power density on the target (for fixed total laser power influenced by beam size on target) strongly influences the charge state distribution of the plasma
The different charge states of the plasma are separated by the drift longitudinally (higher charge states first) and reduce space charge in the acceleration gap
Imperial College London 26
Production of negatively charged ion beams
Three Types of H- Ion Sources are in use
bull Surface conversion sources
bull Volume production sources
bull Hybrid production sources
Conserving energy when forming a negative ion through direct electron attachment the excess energy has to be dissipated through a photon A + e = Amacr + But radiative Capture is rare (5bull10-22cm2 for H2)
Higher cross sections (~10-20cm2 for H2 and Ee gt10 eV) can be realized when the excess energy can be transferred to a third particle M + e = A + B + e and sometimes = A + Bmacr
Cs can be used as an electron donator but the ionisation energy of 39 eV is much higher than the 075 eV electron affinity of H- =gt Surface treatment
Even better are processes which excite a molecule to the edge of breakup (vibrationally excited 4ltnlt12) and then dissociated by a slow electron
Imperial College London 27
Production of negatively charged ion beams
anode
cathode
gasin let solenoid filter
extractore -gtHslow
-driver
e -gtHfast 2
Magnetic dipole fields can be used as filters
to create areas of different electron
temperatures
Cross sections for different production
and destruction mechanisms
Imperial College London 28
Sources using surface production
Schematic layout of the LANCE surface source using a filament driven gas discharge for plasma production and surface conversion on a Cs target for H- formation
Picture of the LANCE surface source
Imperial College London 29
Sources using volume productioncopperm agnetiso latorwater
plasm a-cham ber
plasm a-electrode
screening-e lectrode
electron-dum ping
solenoid bending-m agnet
soleniod
cathodeand
gasin let
filter-m agnet
grid
The small experimental H- source in Frankfurt used a hot cathode driven gas discharge dipole fields and a Pt surface
cover for the reduction of the dissociation of the H2 molecules
Imperial College London 30
Sources using hybrid production schemes
The RAL H- source uses a Penning discharge (dipole for plasma
production and to influence electron temperature) and Cs injection
The SNS H- source developed in Berkley uses RF to produce the plasma dipoles to influence the electron density and a Cs collar
Imperial College London 31
The extraction of particle beams
Imperial College London 32
The space charge limit and Child-Langmuirs law
Imperial College London 33
The space charge limit and Child-Langmuirs law
Imperial College London 34
External and internal fields in the extractor laminar flow and pierce angle
Imperial College London 35
External and internal fields in the extractor laminar flow and pierce angle
Imperial College London 36
The beam emittance the acceptance of the extraction system and the conservation of the phase space
Imperial College London 37
The beam emittance the acceptance of the extraction system and the conservation of the phase space
Imperial College London 38
The beam emittance the acceptance of the extraction system and the conservation of the phase space
Imperial College London 11
Production of high currents of single charge state ion beams
For efficient ion production the electron energy should be app 2-4 times the
ionization energy of the ion
The impact of electron with gaseous atoms is mostly used for the
production of ion beams
Imperial College London 12
Production of high currents of single charge state ion beams
A Townsend gas discharge using an avalanche effect is an very effective way to produce a high amount of ions Therefore the Paschen criteria has to be fulfilled To improve the gas
discharge and to enhance plasma confinement magnetic fields are used
Imperial College London 13
Penning sources
The Penning Ion Source or PIG source (Philips Ionization vacuum Gauge) invented by Penning in 1937 uses a a dipole field for plasma confinement
The strong magnetic dipole field gives high efficiency as electrons oscillate inside the hollow anode between the the two cathodes at each end
The Lifetime of the source limited by sputtering of the cathodes especially for highly charged heavy ion operation
Imperial College London 14
Magnetron sources
The Magnetron ion source which was first presented by Van Voorhis in 1934 uses a solenoidal magnetic field for plasma confinement The field of ~ 01 T is generated with an external solenoid surrounding the ion source The chamber wall serves as anode while the cathode provides electrons through thermionic emission The filament mounted parallel to the magnetic field forces the electrons to spiral As with Penning sources the Lifetime of the source limited by sputtering of the cathodes especially for highly charged heavy ion operation
Imperial College London 15
Hot cathode sources
Filament Ion Source
Discharge in the plasma chamber is driven by the electrons delivered by the filament
1048774single charged ions up to 100 mA
bull Plasma enclosure by magnets
bull Pressure range 10-1 - 10-3 mbar
bull Discharge voltage 20 - 200 V (depending on ionization
voltage)bull Discharge current 10 - 500 A
100 m m
copperiso lator
w ater
steel
brass
m agnets
ground-electrode
screening-e lectrode
plasm a-electrode
B x
B z
C oSm -m agnets
gasin le tcathode
solenoid
filter-m agnet
Imperial College London 16
RF sources
Non resonant excitation of plasma by RF Only lower charge states available (low electron energy)
but high beam currents possible
Internal antenna to feed RF power into plasma =gt limited lifetime of antenna due to sputtering strong coupling of RF into plasma and good plasma confinement
Imperial College London 17
RF sources
Production of large ion currents (Igt1 A) of single charged ions for surface
treatment or plasma heating (tokamaks) Multiaperture extraction therefore difficult to feed beam into conventional accelerator structure
External antenna to feed RF power into plasma =gt Long lifetime of antenna but chamber has to be of non conducting material
Imperial College London 18
Production of high charge state ions
The PLASMA created is increased in density by electron
bombardment The maximum charge state that will be obtained depends on the incident electron energy
e + X = X+ + 2e
For multi-charge states
e + X i+ = X (i+1)+ + 2e
higher electron energies are required since electrons have to be removed from inner shells The maximum charge state is limited by the incident electron
energy
Imperial College London 19
Electron Cyclotron Resonance Sourcehf = cyc = (em) B
Radial and axial magnetic field distribution for the confinement of the source plasma
Only at the centre of the source the cyclotron condition for the electrons is full filled
(01-1 kW)
Extracted ion currents for different charge states of Argon
Imperial College London 20
Electron Cyclotron Resonance source
By variation of the longitudinal enclosing magnetic mirror configuration the
charge distribution can be influenced
Schematic layout of an ECR source for the production of radioactive
ion beams
Imperial College London 21
Electron Beam Ion Source
nominal valuesmax
valuesunits
electron beam current 350 1300 mA
electron beam energy 20 275 keV
trap length 12 - m
magnetic field 15 5 T
charge per pulse 1-2 4 nC
ion pulse length 005-100 - micros
containment time 20-2000 - ms
Parameters of CRYSIS Upper First EBIS IEL-1 build by Donets in 1968 lower Evolution of charge state distribution of nitrogen ions at Ee=545 keV
17 cm
CRYogenic Stockholm Ion Source
Imperial College London 22
Electron Beam Ion Source
Ion current extracted from an EBIS as a function of the
charge state for Na ions (Ne gas was added)
Comparison of the extractable (electric)
current between ECR and EBIS
Total ion charge trapped in an EBIS as a function of confinement time for different electron beam currents
Imperial College London 23
Laser Ion Sources
Schematic drawing of the experimental set up of a laser ion source By the impact of the laser with the target a plasma is created which expands
in the drift chamber and then is accelerated in the extraction gap
Imperial College London 24
Laser Ion Sources
The different charge states of the plasma are separated by the drift longitudinally and reduce space charge in the acceleration gap
By interaction of the plasma electrons with the electric field of the laser pulse the electrons are heated This leads to a shift of the charge state distribution of the plasma ions towards higher charge states
Imperial College London 25
Laser Ion Sources
The available laser power density on the target (for fixed total laser power influenced by beam size on target) strongly influences the charge state distribution of the plasma
The different charge states of the plasma are separated by the drift longitudinally (higher charge states first) and reduce space charge in the acceleration gap
Imperial College London 26
Production of negatively charged ion beams
Three Types of H- Ion Sources are in use
bull Surface conversion sources
bull Volume production sources
bull Hybrid production sources
Conserving energy when forming a negative ion through direct electron attachment the excess energy has to be dissipated through a photon A + e = Amacr + But radiative Capture is rare (5bull10-22cm2 for H2)
Higher cross sections (~10-20cm2 for H2 and Ee gt10 eV) can be realized when the excess energy can be transferred to a third particle M + e = A + B + e and sometimes = A + Bmacr
Cs can be used as an electron donator but the ionisation energy of 39 eV is much higher than the 075 eV electron affinity of H- =gt Surface treatment
Even better are processes which excite a molecule to the edge of breakup (vibrationally excited 4ltnlt12) and then dissociated by a slow electron
Imperial College London 27
Production of negatively charged ion beams
anode
cathode
gasin let solenoid filter
extractore -gtHslow
-driver
e -gtHfast 2
Magnetic dipole fields can be used as filters
to create areas of different electron
temperatures
Cross sections for different production
and destruction mechanisms
Imperial College London 28
Sources using surface production
Schematic layout of the LANCE surface source using a filament driven gas discharge for plasma production and surface conversion on a Cs target for H- formation
Picture of the LANCE surface source
Imperial College London 29
Sources using volume productioncopperm agnetiso latorwater
plasm a-cham ber
plasm a-electrode
screening-e lectrode
electron-dum ping
solenoid bending-m agnet
soleniod
cathodeand
gasin let
filter-m agnet
grid
The small experimental H- source in Frankfurt used a hot cathode driven gas discharge dipole fields and a Pt surface
cover for the reduction of the dissociation of the H2 molecules
Imperial College London 30
Sources using hybrid production schemes
The RAL H- source uses a Penning discharge (dipole for plasma
production and to influence electron temperature) and Cs injection
The SNS H- source developed in Berkley uses RF to produce the plasma dipoles to influence the electron density and a Cs collar
Imperial College London 31
The extraction of particle beams
Imperial College London 32
The space charge limit and Child-Langmuirs law
Imperial College London 33
The space charge limit and Child-Langmuirs law
Imperial College London 34
External and internal fields in the extractor laminar flow and pierce angle
Imperial College London 35
External and internal fields in the extractor laminar flow and pierce angle
Imperial College London 36
The beam emittance the acceptance of the extraction system and the conservation of the phase space
Imperial College London 37
The beam emittance the acceptance of the extraction system and the conservation of the phase space
Imperial College London 38
The beam emittance the acceptance of the extraction system and the conservation of the phase space
Imperial College London 12
Production of high currents of single charge state ion beams
A Townsend gas discharge using an avalanche effect is an very effective way to produce a high amount of ions Therefore the Paschen criteria has to be fulfilled To improve the gas
discharge and to enhance plasma confinement magnetic fields are used
Imperial College London 13
Penning sources
The Penning Ion Source or PIG source (Philips Ionization vacuum Gauge) invented by Penning in 1937 uses a a dipole field for plasma confinement
The strong magnetic dipole field gives high efficiency as electrons oscillate inside the hollow anode between the the two cathodes at each end
The Lifetime of the source limited by sputtering of the cathodes especially for highly charged heavy ion operation
Imperial College London 14
Magnetron sources
The Magnetron ion source which was first presented by Van Voorhis in 1934 uses a solenoidal magnetic field for plasma confinement The field of ~ 01 T is generated with an external solenoid surrounding the ion source The chamber wall serves as anode while the cathode provides electrons through thermionic emission The filament mounted parallel to the magnetic field forces the electrons to spiral As with Penning sources the Lifetime of the source limited by sputtering of the cathodes especially for highly charged heavy ion operation
Imperial College London 15
Hot cathode sources
Filament Ion Source
Discharge in the plasma chamber is driven by the electrons delivered by the filament
1048774single charged ions up to 100 mA
bull Plasma enclosure by magnets
bull Pressure range 10-1 - 10-3 mbar
bull Discharge voltage 20 - 200 V (depending on ionization
voltage)bull Discharge current 10 - 500 A
100 m m
copperiso lator
w ater
steel
brass
m agnets
ground-electrode
screening-e lectrode
plasm a-electrode
B x
B z
C oSm -m agnets
gasin le tcathode
solenoid
filter-m agnet
Imperial College London 16
RF sources
Non resonant excitation of plasma by RF Only lower charge states available (low electron energy)
but high beam currents possible
Internal antenna to feed RF power into plasma =gt limited lifetime of antenna due to sputtering strong coupling of RF into plasma and good plasma confinement
Imperial College London 17
RF sources
Production of large ion currents (Igt1 A) of single charged ions for surface
treatment or plasma heating (tokamaks) Multiaperture extraction therefore difficult to feed beam into conventional accelerator structure
External antenna to feed RF power into plasma =gt Long lifetime of antenna but chamber has to be of non conducting material
Imperial College London 18
Production of high charge state ions
The PLASMA created is increased in density by electron
bombardment The maximum charge state that will be obtained depends on the incident electron energy
e + X = X+ + 2e
For multi-charge states
e + X i+ = X (i+1)+ + 2e
higher electron energies are required since electrons have to be removed from inner shells The maximum charge state is limited by the incident electron
energy
Imperial College London 19
Electron Cyclotron Resonance Sourcehf = cyc = (em) B
Radial and axial magnetic field distribution for the confinement of the source plasma
Only at the centre of the source the cyclotron condition for the electrons is full filled
(01-1 kW)
Extracted ion currents for different charge states of Argon
Imperial College London 20
Electron Cyclotron Resonance source
By variation of the longitudinal enclosing magnetic mirror configuration the
charge distribution can be influenced
Schematic layout of an ECR source for the production of radioactive
ion beams
Imperial College London 21
Electron Beam Ion Source
nominal valuesmax
valuesunits
electron beam current 350 1300 mA
electron beam energy 20 275 keV
trap length 12 - m
magnetic field 15 5 T
charge per pulse 1-2 4 nC
ion pulse length 005-100 - micros
containment time 20-2000 - ms
Parameters of CRYSIS Upper First EBIS IEL-1 build by Donets in 1968 lower Evolution of charge state distribution of nitrogen ions at Ee=545 keV
17 cm
CRYogenic Stockholm Ion Source
Imperial College London 22
Electron Beam Ion Source
Ion current extracted from an EBIS as a function of the
charge state for Na ions (Ne gas was added)
Comparison of the extractable (electric)
current between ECR and EBIS
Total ion charge trapped in an EBIS as a function of confinement time for different electron beam currents
Imperial College London 23
Laser Ion Sources
Schematic drawing of the experimental set up of a laser ion source By the impact of the laser with the target a plasma is created which expands
in the drift chamber and then is accelerated in the extraction gap
Imperial College London 24
Laser Ion Sources
The different charge states of the plasma are separated by the drift longitudinally and reduce space charge in the acceleration gap
By interaction of the plasma electrons with the electric field of the laser pulse the electrons are heated This leads to a shift of the charge state distribution of the plasma ions towards higher charge states
Imperial College London 25
Laser Ion Sources
The available laser power density on the target (for fixed total laser power influenced by beam size on target) strongly influences the charge state distribution of the plasma
The different charge states of the plasma are separated by the drift longitudinally (higher charge states first) and reduce space charge in the acceleration gap
Imperial College London 26
Production of negatively charged ion beams
Three Types of H- Ion Sources are in use
bull Surface conversion sources
bull Volume production sources
bull Hybrid production sources
Conserving energy when forming a negative ion through direct electron attachment the excess energy has to be dissipated through a photon A + e = Amacr + But radiative Capture is rare (5bull10-22cm2 for H2)
Higher cross sections (~10-20cm2 for H2 and Ee gt10 eV) can be realized when the excess energy can be transferred to a third particle M + e = A + B + e and sometimes = A + Bmacr
Cs can be used as an electron donator but the ionisation energy of 39 eV is much higher than the 075 eV electron affinity of H- =gt Surface treatment
Even better are processes which excite a molecule to the edge of breakup (vibrationally excited 4ltnlt12) and then dissociated by a slow electron
Imperial College London 27
Production of negatively charged ion beams
anode
cathode
gasin let solenoid filter
extractore -gtHslow
-driver
e -gtHfast 2
Magnetic dipole fields can be used as filters
to create areas of different electron
temperatures
Cross sections for different production
and destruction mechanisms
Imperial College London 28
Sources using surface production
Schematic layout of the LANCE surface source using a filament driven gas discharge for plasma production and surface conversion on a Cs target for H- formation
Picture of the LANCE surface source
Imperial College London 29
Sources using volume productioncopperm agnetiso latorwater
plasm a-cham ber
plasm a-electrode
screening-e lectrode
electron-dum ping
solenoid bending-m agnet
soleniod
cathodeand
gasin let
filter-m agnet
grid
The small experimental H- source in Frankfurt used a hot cathode driven gas discharge dipole fields and a Pt surface
cover for the reduction of the dissociation of the H2 molecules
Imperial College London 30
Sources using hybrid production schemes
The RAL H- source uses a Penning discharge (dipole for plasma
production and to influence electron temperature) and Cs injection
The SNS H- source developed in Berkley uses RF to produce the plasma dipoles to influence the electron density and a Cs collar
Imperial College London 31
The extraction of particle beams
Imperial College London 32
The space charge limit and Child-Langmuirs law
Imperial College London 33
The space charge limit and Child-Langmuirs law
Imperial College London 34
External and internal fields in the extractor laminar flow and pierce angle
Imperial College London 35
External and internal fields in the extractor laminar flow and pierce angle
Imperial College London 36
The beam emittance the acceptance of the extraction system and the conservation of the phase space
Imperial College London 37
The beam emittance the acceptance of the extraction system and the conservation of the phase space
Imperial College London 38
The beam emittance the acceptance of the extraction system and the conservation of the phase space
Imperial College London 13
Penning sources
The Penning Ion Source or PIG source (Philips Ionization vacuum Gauge) invented by Penning in 1937 uses a a dipole field for plasma confinement
The strong magnetic dipole field gives high efficiency as electrons oscillate inside the hollow anode between the the two cathodes at each end
The Lifetime of the source limited by sputtering of the cathodes especially for highly charged heavy ion operation
Imperial College London 14
Magnetron sources
The Magnetron ion source which was first presented by Van Voorhis in 1934 uses a solenoidal magnetic field for plasma confinement The field of ~ 01 T is generated with an external solenoid surrounding the ion source The chamber wall serves as anode while the cathode provides electrons through thermionic emission The filament mounted parallel to the magnetic field forces the electrons to spiral As with Penning sources the Lifetime of the source limited by sputtering of the cathodes especially for highly charged heavy ion operation
Imperial College London 15
Hot cathode sources
Filament Ion Source
Discharge in the plasma chamber is driven by the electrons delivered by the filament
1048774single charged ions up to 100 mA
bull Plasma enclosure by magnets
bull Pressure range 10-1 - 10-3 mbar
bull Discharge voltage 20 - 200 V (depending on ionization
voltage)bull Discharge current 10 - 500 A
100 m m
copperiso lator
w ater
steel
brass
m agnets
ground-electrode
screening-e lectrode
plasm a-electrode
B x
B z
C oSm -m agnets
gasin le tcathode
solenoid
filter-m agnet
Imperial College London 16
RF sources
Non resonant excitation of plasma by RF Only lower charge states available (low electron energy)
but high beam currents possible
Internal antenna to feed RF power into plasma =gt limited lifetime of antenna due to sputtering strong coupling of RF into plasma and good plasma confinement
Imperial College London 17
RF sources
Production of large ion currents (Igt1 A) of single charged ions for surface
treatment or plasma heating (tokamaks) Multiaperture extraction therefore difficult to feed beam into conventional accelerator structure
External antenna to feed RF power into plasma =gt Long lifetime of antenna but chamber has to be of non conducting material
Imperial College London 18
Production of high charge state ions
The PLASMA created is increased in density by electron
bombardment The maximum charge state that will be obtained depends on the incident electron energy
e + X = X+ + 2e
For multi-charge states
e + X i+ = X (i+1)+ + 2e
higher electron energies are required since electrons have to be removed from inner shells The maximum charge state is limited by the incident electron
energy
Imperial College London 19
Electron Cyclotron Resonance Sourcehf = cyc = (em) B
Radial and axial magnetic field distribution for the confinement of the source plasma
Only at the centre of the source the cyclotron condition for the electrons is full filled
(01-1 kW)
Extracted ion currents for different charge states of Argon
Imperial College London 20
Electron Cyclotron Resonance source
By variation of the longitudinal enclosing magnetic mirror configuration the
charge distribution can be influenced
Schematic layout of an ECR source for the production of radioactive
ion beams
Imperial College London 21
Electron Beam Ion Source
nominal valuesmax
valuesunits
electron beam current 350 1300 mA
electron beam energy 20 275 keV
trap length 12 - m
magnetic field 15 5 T
charge per pulse 1-2 4 nC
ion pulse length 005-100 - micros
containment time 20-2000 - ms
Parameters of CRYSIS Upper First EBIS IEL-1 build by Donets in 1968 lower Evolution of charge state distribution of nitrogen ions at Ee=545 keV
17 cm
CRYogenic Stockholm Ion Source
Imperial College London 22
Electron Beam Ion Source
Ion current extracted from an EBIS as a function of the
charge state for Na ions (Ne gas was added)
Comparison of the extractable (electric)
current between ECR and EBIS
Total ion charge trapped in an EBIS as a function of confinement time for different electron beam currents
Imperial College London 23
Laser Ion Sources
Schematic drawing of the experimental set up of a laser ion source By the impact of the laser with the target a plasma is created which expands
in the drift chamber and then is accelerated in the extraction gap
Imperial College London 24
Laser Ion Sources
The different charge states of the plasma are separated by the drift longitudinally and reduce space charge in the acceleration gap
By interaction of the plasma electrons with the electric field of the laser pulse the electrons are heated This leads to a shift of the charge state distribution of the plasma ions towards higher charge states
Imperial College London 25
Laser Ion Sources
The available laser power density on the target (for fixed total laser power influenced by beam size on target) strongly influences the charge state distribution of the plasma
The different charge states of the plasma are separated by the drift longitudinally (higher charge states first) and reduce space charge in the acceleration gap
Imperial College London 26
Production of negatively charged ion beams
Three Types of H- Ion Sources are in use
bull Surface conversion sources
bull Volume production sources
bull Hybrid production sources
Conserving energy when forming a negative ion through direct electron attachment the excess energy has to be dissipated through a photon A + e = Amacr + But radiative Capture is rare (5bull10-22cm2 for H2)
Higher cross sections (~10-20cm2 for H2 and Ee gt10 eV) can be realized when the excess energy can be transferred to a third particle M + e = A + B + e and sometimes = A + Bmacr
Cs can be used as an electron donator but the ionisation energy of 39 eV is much higher than the 075 eV electron affinity of H- =gt Surface treatment
Even better are processes which excite a molecule to the edge of breakup (vibrationally excited 4ltnlt12) and then dissociated by a slow electron
Imperial College London 27
Production of negatively charged ion beams
anode
cathode
gasin let solenoid filter
extractore -gtHslow
-driver
e -gtHfast 2
Magnetic dipole fields can be used as filters
to create areas of different electron
temperatures
Cross sections for different production
and destruction mechanisms
Imperial College London 28
Sources using surface production
Schematic layout of the LANCE surface source using a filament driven gas discharge for plasma production and surface conversion on a Cs target for H- formation
Picture of the LANCE surface source
Imperial College London 29
Sources using volume productioncopperm agnetiso latorwater
plasm a-cham ber
plasm a-electrode
screening-e lectrode
electron-dum ping
solenoid bending-m agnet
soleniod
cathodeand
gasin let
filter-m agnet
grid
The small experimental H- source in Frankfurt used a hot cathode driven gas discharge dipole fields and a Pt surface
cover for the reduction of the dissociation of the H2 molecules
Imperial College London 30
Sources using hybrid production schemes
The RAL H- source uses a Penning discharge (dipole for plasma
production and to influence electron temperature) and Cs injection
The SNS H- source developed in Berkley uses RF to produce the plasma dipoles to influence the electron density and a Cs collar
Imperial College London 31
The extraction of particle beams
Imperial College London 32
The space charge limit and Child-Langmuirs law
Imperial College London 33
The space charge limit and Child-Langmuirs law
Imperial College London 34
External and internal fields in the extractor laminar flow and pierce angle
Imperial College London 35
External and internal fields in the extractor laminar flow and pierce angle
Imperial College London 36
The beam emittance the acceptance of the extraction system and the conservation of the phase space
Imperial College London 37
The beam emittance the acceptance of the extraction system and the conservation of the phase space
Imperial College London 38
The beam emittance the acceptance of the extraction system and the conservation of the phase space
Imperial College London 14
Magnetron sources
The Magnetron ion source which was first presented by Van Voorhis in 1934 uses a solenoidal magnetic field for plasma confinement The field of ~ 01 T is generated with an external solenoid surrounding the ion source The chamber wall serves as anode while the cathode provides electrons through thermionic emission The filament mounted parallel to the magnetic field forces the electrons to spiral As with Penning sources the Lifetime of the source limited by sputtering of the cathodes especially for highly charged heavy ion operation
Imperial College London 15
Hot cathode sources
Filament Ion Source
Discharge in the plasma chamber is driven by the electrons delivered by the filament
1048774single charged ions up to 100 mA
bull Plasma enclosure by magnets
bull Pressure range 10-1 - 10-3 mbar
bull Discharge voltage 20 - 200 V (depending on ionization
voltage)bull Discharge current 10 - 500 A
100 m m
copperiso lator
w ater
steel
brass
m agnets
ground-electrode
screening-e lectrode
plasm a-electrode
B x
B z
C oSm -m agnets
gasin le tcathode
solenoid
filter-m agnet
Imperial College London 16
RF sources
Non resonant excitation of plasma by RF Only lower charge states available (low electron energy)
but high beam currents possible
Internal antenna to feed RF power into plasma =gt limited lifetime of antenna due to sputtering strong coupling of RF into plasma and good plasma confinement
Imperial College London 17
RF sources
Production of large ion currents (Igt1 A) of single charged ions for surface
treatment or plasma heating (tokamaks) Multiaperture extraction therefore difficult to feed beam into conventional accelerator structure
External antenna to feed RF power into plasma =gt Long lifetime of antenna but chamber has to be of non conducting material
Imperial College London 18
Production of high charge state ions
The PLASMA created is increased in density by electron
bombardment The maximum charge state that will be obtained depends on the incident electron energy
e + X = X+ + 2e
For multi-charge states
e + X i+ = X (i+1)+ + 2e
higher electron energies are required since electrons have to be removed from inner shells The maximum charge state is limited by the incident electron
energy
Imperial College London 19
Electron Cyclotron Resonance Sourcehf = cyc = (em) B
Radial and axial magnetic field distribution for the confinement of the source plasma
Only at the centre of the source the cyclotron condition for the electrons is full filled
(01-1 kW)
Extracted ion currents for different charge states of Argon
Imperial College London 20
Electron Cyclotron Resonance source
By variation of the longitudinal enclosing magnetic mirror configuration the
charge distribution can be influenced
Schematic layout of an ECR source for the production of radioactive
ion beams
Imperial College London 21
Electron Beam Ion Source
nominal valuesmax
valuesunits
electron beam current 350 1300 mA
electron beam energy 20 275 keV
trap length 12 - m
magnetic field 15 5 T
charge per pulse 1-2 4 nC
ion pulse length 005-100 - micros
containment time 20-2000 - ms
Parameters of CRYSIS Upper First EBIS IEL-1 build by Donets in 1968 lower Evolution of charge state distribution of nitrogen ions at Ee=545 keV
17 cm
CRYogenic Stockholm Ion Source
Imperial College London 22
Electron Beam Ion Source
Ion current extracted from an EBIS as a function of the
charge state for Na ions (Ne gas was added)
Comparison of the extractable (electric)
current between ECR and EBIS
Total ion charge trapped in an EBIS as a function of confinement time for different electron beam currents
Imperial College London 23
Laser Ion Sources
Schematic drawing of the experimental set up of a laser ion source By the impact of the laser with the target a plasma is created which expands
in the drift chamber and then is accelerated in the extraction gap
Imperial College London 24
Laser Ion Sources
The different charge states of the plasma are separated by the drift longitudinally and reduce space charge in the acceleration gap
By interaction of the plasma electrons with the electric field of the laser pulse the electrons are heated This leads to a shift of the charge state distribution of the plasma ions towards higher charge states
Imperial College London 25
Laser Ion Sources
The available laser power density on the target (for fixed total laser power influenced by beam size on target) strongly influences the charge state distribution of the plasma
The different charge states of the plasma are separated by the drift longitudinally (higher charge states first) and reduce space charge in the acceleration gap
Imperial College London 26
Production of negatively charged ion beams
Three Types of H- Ion Sources are in use
bull Surface conversion sources
bull Volume production sources
bull Hybrid production sources
Conserving energy when forming a negative ion through direct electron attachment the excess energy has to be dissipated through a photon A + e = Amacr + But radiative Capture is rare (5bull10-22cm2 for H2)
Higher cross sections (~10-20cm2 for H2 and Ee gt10 eV) can be realized when the excess energy can be transferred to a third particle M + e = A + B + e and sometimes = A + Bmacr
Cs can be used as an electron donator but the ionisation energy of 39 eV is much higher than the 075 eV electron affinity of H- =gt Surface treatment
Even better are processes which excite a molecule to the edge of breakup (vibrationally excited 4ltnlt12) and then dissociated by a slow electron
Imperial College London 27
Production of negatively charged ion beams
anode
cathode
gasin let solenoid filter
extractore -gtHslow
-driver
e -gtHfast 2
Magnetic dipole fields can be used as filters
to create areas of different electron
temperatures
Cross sections for different production
and destruction mechanisms
Imperial College London 28
Sources using surface production
Schematic layout of the LANCE surface source using a filament driven gas discharge for plasma production and surface conversion on a Cs target for H- formation
Picture of the LANCE surface source
Imperial College London 29
Sources using volume productioncopperm agnetiso latorwater
plasm a-cham ber
plasm a-electrode
screening-e lectrode
electron-dum ping
solenoid bending-m agnet
soleniod
cathodeand
gasin let
filter-m agnet
grid
The small experimental H- source in Frankfurt used a hot cathode driven gas discharge dipole fields and a Pt surface
cover for the reduction of the dissociation of the H2 molecules
Imperial College London 30
Sources using hybrid production schemes
The RAL H- source uses a Penning discharge (dipole for plasma
production and to influence electron temperature) and Cs injection
The SNS H- source developed in Berkley uses RF to produce the plasma dipoles to influence the electron density and a Cs collar
Imperial College London 31
The extraction of particle beams
Imperial College London 32
The space charge limit and Child-Langmuirs law
Imperial College London 33
The space charge limit and Child-Langmuirs law
Imperial College London 34
External and internal fields in the extractor laminar flow and pierce angle
Imperial College London 35
External and internal fields in the extractor laminar flow and pierce angle
Imperial College London 36
The beam emittance the acceptance of the extraction system and the conservation of the phase space
Imperial College London 37
The beam emittance the acceptance of the extraction system and the conservation of the phase space
Imperial College London 38
The beam emittance the acceptance of the extraction system and the conservation of the phase space
Imperial College London 15
Hot cathode sources
Filament Ion Source
Discharge in the plasma chamber is driven by the electrons delivered by the filament
1048774single charged ions up to 100 mA
bull Plasma enclosure by magnets
bull Pressure range 10-1 - 10-3 mbar
bull Discharge voltage 20 - 200 V (depending on ionization
voltage)bull Discharge current 10 - 500 A
100 m m
copperiso lator
w ater
steel
brass
m agnets
ground-electrode
screening-e lectrode
plasm a-electrode
B x
B z
C oSm -m agnets
gasin le tcathode
solenoid
filter-m agnet
Imperial College London 16
RF sources
Non resonant excitation of plasma by RF Only lower charge states available (low electron energy)
but high beam currents possible
Internal antenna to feed RF power into plasma =gt limited lifetime of antenna due to sputtering strong coupling of RF into plasma and good plasma confinement
Imperial College London 17
RF sources
Production of large ion currents (Igt1 A) of single charged ions for surface
treatment or plasma heating (tokamaks) Multiaperture extraction therefore difficult to feed beam into conventional accelerator structure
External antenna to feed RF power into plasma =gt Long lifetime of antenna but chamber has to be of non conducting material
Imperial College London 18
Production of high charge state ions
The PLASMA created is increased in density by electron
bombardment The maximum charge state that will be obtained depends on the incident electron energy
e + X = X+ + 2e
For multi-charge states
e + X i+ = X (i+1)+ + 2e
higher electron energies are required since electrons have to be removed from inner shells The maximum charge state is limited by the incident electron
energy
Imperial College London 19
Electron Cyclotron Resonance Sourcehf = cyc = (em) B
Radial and axial magnetic field distribution for the confinement of the source plasma
Only at the centre of the source the cyclotron condition for the electrons is full filled
(01-1 kW)
Extracted ion currents for different charge states of Argon
Imperial College London 20
Electron Cyclotron Resonance source
By variation of the longitudinal enclosing magnetic mirror configuration the
charge distribution can be influenced
Schematic layout of an ECR source for the production of radioactive
ion beams
Imperial College London 21
Electron Beam Ion Source
nominal valuesmax
valuesunits
electron beam current 350 1300 mA
electron beam energy 20 275 keV
trap length 12 - m
magnetic field 15 5 T
charge per pulse 1-2 4 nC
ion pulse length 005-100 - micros
containment time 20-2000 - ms
Parameters of CRYSIS Upper First EBIS IEL-1 build by Donets in 1968 lower Evolution of charge state distribution of nitrogen ions at Ee=545 keV
17 cm
CRYogenic Stockholm Ion Source
Imperial College London 22
Electron Beam Ion Source
Ion current extracted from an EBIS as a function of the
charge state for Na ions (Ne gas was added)
Comparison of the extractable (electric)
current between ECR and EBIS
Total ion charge trapped in an EBIS as a function of confinement time for different electron beam currents
Imperial College London 23
Laser Ion Sources
Schematic drawing of the experimental set up of a laser ion source By the impact of the laser with the target a plasma is created which expands
in the drift chamber and then is accelerated in the extraction gap
Imperial College London 24
Laser Ion Sources
The different charge states of the plasma are separated by the drift longitudinally and reduce space charge in the acceleration gap
By interaction of the plasma electrons with the electric field of the laser pulse the electrons are heated This leads to a shift of the charge state distribution of the plasma ions towards higher charge states
Imperial College London 25
Laser Ion Sources
The available laser power density on the target (for fixed total laser power influenced by beam size on target) strongly influences the charge state distribution of the plasma
The different charge states of the plasma are separated by the drift longitudinally (higher charge states first) and reduce space charge in the acceleration gap
Imperial College London 26
Production of negatively charged ion beams
Three Types of H- Ion Sources are in use
bull Surface conversion sources
bull Volume production sources
bull Hybrid production sources
Conserving energy when forming a negative ion through direct electron attachment the excess energy has to be dissipated through a photon A + e = Amacr + But radiative Capture is rare (5bull10-22cm2 for H2)
Higher cross sections (~10-20cm2 for H2 and Ee gt10 eV) can be realized when the excess energy can be transferred to a third particle M + e = A + B + e and sometimes = A + Bmacr
Cs can be used as an electron donator but the ionisation energy of 39 eV is much higher than the 075 eV electron affinity of H- =gt Surface treatment
Even better are processes which excite a molecule to the edge of breakup (vibrationally excited 4ltnlt12) and then dissociated by a slow electron
Imperial College London 27
Production of negatively charged ion beams
anode
cathode
gasin let solenoid filter
extractore -gtHslow
-driver
e -gtHfast 2
Magnetic dipole fields can be used as filters
to create areas of different electron
temperatures
Cross sections for different production
and destruction mechanisms
Imperial College London 28
Sources using surface production
Schematic layout of the LANCE surface source using a filament driven gas discharge for plasma production and surface conversion on a Cs target for H- formation
Picture of the LANCE surface source
Imperial College London 29
Sources using volume productioncopperm agnetiso latorwater
plasm a-cham ber
plasm a-electrode
screening-e lectrode
electron-dum ping
solenoid bending-m agnet
soleniod
cathodeand
gasin let
filter-m agnet
grid
The small experimental H- source in Frankfurt used a hot cathode driven gas discharge dipole fields and a Pt surface
cover for the reduction of the dissociation of the H2 molecules
Imperial College London 30
Sources using hybrid production schemes
The RAL H- source uses a Penning discharge (dipole for plasma
production and to influence electron temperature) and Cs injection
The SNS H- source developed in Berkley uses RF to produce the plasma dipoles to influence the electron density and a Cs collar
Imperial College London 31
The extraction of particle beams
Imperial College London 32
The space charge limit and Child-Langmuirs law
Imperial College London 33
The space charge limit and Child-Langmuirs law
Imperial College London 34
External and internal fields in the extractor laminar flow and pierce angle
Imperial College London 35
External and internal fields in the extractor laminar flow and pierce angle
Imperial College London 36
The beam emittance the acceptance of the extraction system and the conservation of the phase space
Imperial College London 37
The beam emittance the acceptance of the extraction system and the conservation of the phase space
Imperial College London 38
The beam emittance the acceptance of the extraction system and the conservation of the phase space
Imperial College London 16
RF sources
Non resonant excitation of plasma by RF Only lower charge states available (low electron energy)
but high beam currents possible
Internal antenna to feed RF power into plasma =gt limited lifetime of antenna due to sputtering strong coupling of RF into plasma and good plasma confinement
Imperial College London 17
RF sources
Production of large ion currents (Igt1 A) of single charged ions for surface
treatment or plasma heating (tokamaks) Multiaperture extraction therefore difficult to feed beam into conventional accelerator structure
External antenna to feed RF power into plasma =gt Long lifetime of antenna but chamber has to be of non conducting material
Imperial College London 18
Production of high charge state ions
The PLASMA created is increased in density by electron
bombardment The maximum charge state that will be obtained depends on the incident electron energy
e + X = X+ + 2e
For multi-charge states
e + X i+ = X (i+1)+ + 2e
higher electron energies are required since electrons have to be removed from inner shells The maximum charge state is limited by the incident electron
energy
Imperial College London 19
Electron Cyclotron Resonance Sourcehf = cyc = (em) B
Radial and axial magnetic field distribution for the confinement of the source plasma
Only at the centre of the source the cyclotron condition for the electrons is full filled
(01-1 kW)
Extracted ion currents for different charge states of Argon
Imperial College London 20
Electron Cyclotron Resonance source
By variation of the longitudinal enclosing magnetic mirror configuration the
charge distribution can be influenced
Schematic layout of an ECR source for the production of radioactive
ion beams
Imperial College London 21
Electron Beam Ion Source
nominal valuesmax
valuesunits
electron beam current 350 1300 mA
electron beam energy 20 275 keV
trap length 12 - m
magnetic field 15 5 T
charge per pulse 1-2 4 nC
ion pulse length 005-100 - micros
containment time 20-2000 - ms
Parameters of CRYSIS Upper First EBIS IEL-1 build by Donets in 1968 lower Evolution of charge state distribution of nitrogen ions at Ee=545 keV
17 cm
CRYogenic Stockholm Ion Source
Imperial College London 22
Electron Beam Ion Source
Ion current extracted from an EBIS as a function of the
charge state for Na ions (Ne gas was added)
Comparison of the extractable (electric)
current between ECR and EBIS
Total ion charge trapped in an EBIS as a function of confinement time for different electron beam currents
Imperial College London 23
Laser Ion Sources
Schematic drawing of the experimental set up of a laser ion source By the impact of the laser with the target a plasma is created which expands
in the drift chamber and then is accelerated in the extraction gap
Imperial College London 24
Laser Ion Sources
The different charge states of the plasma are separated by the drift longitudinally and reduce space charge in the acceleration gap
By interaction of the plasma electrons with the electric field of the laser pulse the electrons are heated This leads to a shift of the charge state distribution of the plasma ions towards higher charge states
Imperial College London 25
Laser Ion Sources
The available laser power density on the target (for fixed total laser power influenced by beam size on target) strongly influences the charge state distribution of the plasma
The different charge states of the plasma are separated by the drift longitudinally (higher charge states first) and reduce space charge in the acceleration gap
Imperial College London 26
Production of negatively charged ion beams
Three Types of H- Ion Sources are in use
bull Surface conversion sources
bull Volume production sources
bull Hybrid production sources
Conserving energy when forming a negative ion through direct electron attachment the excess energy has to be dissipated through a photon A + e = Amacr + But radiative Capture is rare (5bull10-22cm2 for H2)
Higher cross sections (~10-20cm2 for H2 and Ee gt10 eV) can be realized when the excess energy can be transferred to a third particle M + e = A + B + e and sometimes = A + Bmacr
Cs can be used as an electron donator but the ionisation energy of 39 eV is much higher than the 075 eV electron affinity of H- =gt Surface treatment
Even better are processes which excite a molecule to the edge of breakup (vibrationally excited 4ltnlt12) and then dissociated by a slow electron
Imperial College London 27
Production of negatively charged ion beams
anode
cathode
gasin let solenoid filter
extractore -gtHslow
-driver
e -gtHfast 2
Magnetic dipole fields can be used as filters
to create areas of different electron
temperatures
Cross sections for different production
and destruction mechanisms
Imperial College London 28
Sources using surface production
Schematic layout of the LANCE surface source using a filament driven gas discharge for plasma production and surface conversion on a Cs target for H- formation
Picture of the LANCE surface source
Imperial College London 29
Sources using volume productioncopperm agnetiso latorwater
plasm a-cham ber
plasm a-electrode
screening-e lectrode
electron-dum ping
solenoid bending-m agnet
soleniod
cathodeand
gasin let
filter-m agnet
grid
The small experimental H- source in Frankfurt used a hot cathode driven gas discharge dipole fields and a Pt surface
cover for the reduction of the dissociation of the H2 molecules
Imperial College London 30
Sources using hybrid production schemes
The RAL H- source uses a Penning discharge (dipole for plasma
production and to influence electron temperature) and Cs injection
The SNS H- source developed in Berkley uses RF to produce the plasma dipoles to influence the electron density and a Cs collar
Imperial College London 31
The extraction of particle beams
Imperial College London 32
The space charge limit and Child-Langmuirs law
Imperial College London 33
The space charge limit and Child-Langmuirs law
Imperial College London 34
External and internal fields in the extractor laminar flow and pierce angle
Imperial College London 35
External and internal fields in the extractor laminar flow and pierce angle
Imperial College London 36
The beam emittance the acceptance of the extraction system and the conservation of the phase space
Imperial College London 37
The beam emittance the acceptance of the extraction system and the conservation of the phase space
Imperial College London 38
The beam emittance the acceptance of the extraction system and the conservation of the phase space
Imperial College London 17
RF sources
Production of large ion currents (Igt1 A) of single charged ions for surface
treatment or plasma heating (tokamaks) Multiaperture extraction therefore difficult to feed beam into conventional accelerator structure
External antenna to feed RF power into plasma =gt Long lifetime of antenna but chamber has to be of non conducting material
Imperial College London 18
Production of high charge state ions
The PLASMA created is increased in density by electron
bombardment The maximum charge state that will be obtained depends on the incident electron energy
e + X = X+ + 2e
For multi-charge states
e + X i+ = X (i+1)+ + 2e
higher electron energies are required since electrons have to be removed from inner shells The maximum charge state is limited by the incident electron
energy
Imperial College London 19
Electron Cyclotron Resonance Sourcehf = cyc = (em) B
Radial and axial magnetic field distribution for the confinement of the source plasma
Only at the centre of the source the cyclotron condition for the electrons is full filled
(01-1 kW)
Extracted ion currents for different charge states of Argon
Imperial College London 20
Electron Cyclotron Resonance source
By variation of the longitudinal enclosing magnetic mirror configuration the
charge distribution can be influenced
Schematic layout of an ECR source for the production of radioactive
ion beams
Imperial College London 21
Electron Beam Ion Source
nominal valuesmax
valuesunits
electron beam current 350 1300 mA
electron beam energy 20 275 keV
trap length 12 - m
magnetic field 15 5 T
charge per pulse 1-2 4 nC
ion pulse length 005-100 - micros
containment time 20-2000 - ms
Parameters of CRYSIS Upper First EBIS IEL-1 build by Donets in 1968 lower Evolution of charge state distribution of nitrogen ions at Ee=545 keV
17 cm
CRYogenic Stockholm Ion Source
Imperial College London 22
Electron Beam Ion Source
Ion current extracted from an EBIS as a function of the
charge state for Na ions (Ne gas was added)
Comparison of the extractable (electric)
current between ECR and EBIS
Total ion charge trapped in an EBIS as a function of confinement time for different electron beam currents
Imperial College London 23
Laser Ion Sources
Schematic drawing of the experimental set up of a laser ion source By the impact of the laser with the target a plasma is created which expands
in the drift chamber and then is accelerated in the extraction gap
Imperial College London 24
Laser Ion Sources
The different charge states of the plasma are separated by the drift longitudinally and reduce space charge in the acceleration gap
By interaction of the plasma electrons with the electric field of the laser pulse the electrons are heated This leads to a shift of the charge state distribution of the plasma ions towards higher charge states
Imperial College London 25
Laser Ion Sources
The available laser power density on the target (for fixed total laser power influenced by beam size on target) strongly influences the charge state distribution of the plasma
The different charge states of the plasma are separated by the drift longitudinally (higher charge states first) and reduce space charge in the acceleration gap
Imperial College London 26
Production of negatively charged ion beams
Three Types of H- Ion Sources are in use
bull Surface conversion sources
bull Volume production sources
bull Hybrid production sources
Conserving energy when forming a negative ion through direct electron attachment the excess energy has to be dissipated through a photon A + e = Amacr + But radiative Capture is rare (5bull10-22cm2 for H2)
Higher cross sections (~10-20cm2 for H2 and Ee gt10 eV) can be realized when the excess energy can be transferred to a third particle M + e = A + B + e and sometimes = A + Bmacr
Cs can be used as an electron donator but the ionisation energy of 39 eV is much higher than the 075 eV electron affinity of H- =gt Surface treatment
Even better are processes which excite a molecule to the edge of breakup (vibrationally excited 4ltnlt12) and then dissociated by a slow electron
Imperial College London 27
Production of negatively charged ion beams
anode
cathode
gasin let solenoid filter
extractore -gtHslow
-driver
e -gtHfast 2
Magnetic dipole fields can be used as filters
to create areas of different electron
temperatures
Cross sections for different production
and destruction mechanisms
Imperial College London 28
Sources using surface production
Schematic layout of the LANCE surface source using a filament driven gas discharge for plasma production and surface conversion on a Cs target for H- formation
Picture of the LANCE surface source
Imperial College London 29
Sources using volume productioncopperm agnetiso latorwater
plasm a-cham ber
plasm a-electrode
screening-e lectrode
electron-dum ping
solenoid bending-m agnet
soleniod
cathodeand
gasin let
filter-m agnet
grid
The small experimental H- source in Frankfurt used a hot cathode driven gas discharge dipole fields and a Pt surface
cover for the reduction of the dissociation of the H2 molecules
Imperial College London 30
Sources using hybrid production schemes
The RAL H- source uses a Penning discharge (dipole for plasma
production and to influence electron temperature) and Cs injection
The SNS H- source developed in Berkley uses RF to produce the plasma dipoles to influence the electron density and a Cs collar
Imperial College London 31
The extraction of particle beams
Imperial College London 32
The space charge limit and Child-Langmuirs law
Imperial College London 33
The space charge limit and Child-Langmuirs law
Imperial College London 34
External and internal fields in the extractor laminar flow and pierce angle
Imperial College London 35
External and internal fields in the extractor laminar flow and pierce angle
Imperial College London 36
The beam emittance the acceptance of the extraction system and the conservation of the phase space
Imperial College London 37
The beam emittance the acceptance of the extraction system and the conservation of the phase space
Imperial College London 38
The beam emittance the acceptance of the extraction system and the conservation of the phase space
Imperial College London 18
Production of high charge state ions
The PLASMA created is increased in density by electron
bombardment The maximum charge state that will be obtained depends on the incident electron energy
e + X = X+ + 2e
For multi-charge states
e + X i+ = X (i+1)+ + 2e
higher electron energies are required since electrons have to be removed from inner shells The maximum charge state is limited by the incident electron
energy
Imperial College London 19
Electron Cyclotron Resonance Sourcehf = cyc = (em) B
Radial and axial magnetic field distribution for the confinement of the source plasma
Only at the centre of the source the cyclotron condition for the electrons is full filled
(01-1 kW)
Extracted ion currents for different charge states of Argon
Imperial College London 20
Electron Cyclotron Resonance source
By variation of the longitudinal enclosing magnetic mirror configuration the
charge distribution can be influenced
Schematic layout of an ECR source for the production of radioactive
ion beams
Imperial College London 21
Electron Beam Ion Source
nominal valuesmax
valuesunits
electron beam current 350 1300 mA
electron beam energy 20 275 keV
trap length 12 - m
magnetic field 15 5 T
charge per pulse 1-2 4 nC
ion pulse length 005-100 - micros
containment time 20-2000 - ms
Parameters of CRYSIS Upper First EBIS IEL-1 build by Donets in 1968 lower Evolution of charge state distribution of nitrogen ions at Ee=545 keV
17 cm
CRYogenic Stockholm Ion Source
Imperial College London 22
Electron Beam Ion Source
Ion current extracted from an EBIS as a function of the
charge state for Na ions (Ne gas was added)
Comparison of the extractable (electric)
current between ECR and EBIS
Total ion charge trapped in an EBIS as a function of confinement time for different electron beam currents
Imperial College London 23
Laser Ion Sources
Schematic drawing of the experimental set up of a laser ion source By the impact of the laser with the target a plasma is created which expands
in the drift chamber and then is accelerated in the extraction gap
Imperial College London 24
Laser Ion Sources
The different charge states of the plasma are separated by the drift longitudinally and reduce space charge in the acceleration gap
By interaction of the plasma electrons with the electric field of the laser pulse the electrons are heated This leads to a shift of the charge state distribution of the plasma ions towards higher charge states
Imperial College London 25
Laser Ion Sources
The available laser power density on the target (for fixed total laser power influenced by beam size on target) strongly influences the charge state distribution of the plasma
The different charge states of the plasma are separated by the drift longitudinally (higher charge states first) and reduce space charge in the acceleration gap
Imperial College London 26
Production of negatively charged ion beams
Three Types of H- Ion Sources are in use
bull Surface conversion sources
bull Volume production sources
bull Hybrid production sources
Conserving energy when forming a negative ion through direct electron attachment the excess energy has to be dissipated through a photon A + e = Amacr + But radiative Capture is rare (5bull10-22cm2 for H2)
Higher cross sections (~10-20cm2 for H2 and Ee gt10 eV) can be realized when the excess energy can be transferred to a third particle M + e = A + B + e and sometimes = A + Bmacr
Cs can be used as an electron donator but the ionisation energy of 39 eV is much higher than the 075 eV electron affinity of H- =gt Surface treatment
Even better are processes which excite a molecule to the edge of breakup (vibrationally excited 4ltnlt12) and then dissociated by a slow electron
Imperial College London 27
Production of negatively charged ion beams
anode
cathode
gasin let solenoid filter
extractore -gtHslow
-driver
e -gtHfast 2
Magnetic dipole fields can be used as filters
to create areas of different electron
temperatures
Cross sections for different production
and destruction mechanisms
Imperial College London 28
Sources using surface production
Schematic layout of the LANCE surface source using a filament driven gas discharge for plasma production and surface conversion on a Cs target for H- formation
Picture of the LANCE surface source
Imperial College London 29
Sources using volume productioncopperm agnetiso latorwater
plasm a-cham ber
plasm a-electrode
screening-e lectrode
electron-dum ping
solenoid bending-m agnet
soleniod
cathodeand
gasin let
filter-m agnet
grid
The small experimental H- source in Frankfurt used a hot cathode driven gas discharge dipole fields and a Pt surface
cover for the reduction of the dissociation of the H2 molecules
Imperial College London 30
Sources using hybrid production schemes
The RAL H- source uses a Penning discharge (dipole for plasma
production and to influence electron temperature) and Cs injection
The SNS H- source developed in Berkley uses RF to produce the plasma dipoles to influence the electron density and a Cs collar
Imperial College London 31
The extraction of particle beams
Imperial College London 32
The space charge limit and Child-Langmuirs law
Imperial College London 33
The space charge limit and Child-Langmuirs law
Imperial College London 34
External and internal fields in the extractor laminar flow and pierce angle
Imperial College London 35
External and internal fields in the extractor laminar flow and pierce angle
Imperial College London 36
The beam emittance the acceptance of the extraction system and the conservation of the phase space
Imperial College London 37
The beam emittance the acceptance of the extraction system and the conservation of the phase space
Imperial College London 38
The beam emittance the acceptance of the extraction system and the conservation of the phase space
Imperial College London 19
Electron Cyclotron Resonance Sourcehf = cyc = (em) B
Radial and axial magnetic field distribution for the confinement of the source plasma
Only at the centre of the source the cyclotron condition for the electrons is full filled
(01-1 kW)
Extracted ion currents for different charge states of Argon
Imperial College London 20
Electron Cyclotron Resonance source
By variation of the longitudinal enclosing magnetic mirror configuration the
charge distribution can be influenced
Schematic layout of an ECR source for the production of radioactive
ion beams
Imperial College London 21
Electron Beam Ion Source
nominal valuesmax
valuesunits
electron beam current 350 1300 mA
electron beam energy 20 275 keV
trap length 12 - m
magnetic field 15 5 T
charge per pulse 1-2 4 nC
ion pulse length 005-100 - micros
containment time 20-2000 - ms
Parameters of CRYSIS Upper First EBIS IEL-1 build by Donets in 1968 lower Evolution of charge state distribution of nitrogen ions at Ee=545 keV
17 cm
CRYogenic Stockholm Ion Source
Imperial College London 22
Electron Beam Ion Source
Ion current extracted from an EBIS as a function of the
charge state for Na ions (Ne gas was added)
Comparison of the extractable (electric)
current between ECR and EBIS
Total ion charge trapped in an EBIS as a function of confinement time for different electron beam currents
Imperial College London 23
Laser Ion Sources
Schematic drawing of the experimental set up of a laser ion source By the impact of the laser with the target a plasma is created which expands
in the drift chamber and then is accelerated in the extraction gap
Imperial College London 24
Laser Ion Sources
The different charge states of the plasma are separated by the drift longitudinally and reduce space charge in the acceleration gap
By interaction of the plasma electrons with the electric field of the laser pulse the electrons are heated This leads to a shift of the charge state distribution of the plasma ions towards higher charge states
Imperial College London 25
Laser Ion Sources
The available laser power density on the target (for fixed total laser power influenced by beam size on target) strongly influences the charge state distribution of the plasma
The different charge states of the plasma are separated by the drift longitudinally (higher charge states first) and reduce space charge in the acceleration gap
Imperial College London 26
Production of negatively charged ion beams
Three Types of H- Ion Sources are in use
bull Surface conversion sources
bull Volume production sources
bull Hybrid production sources
Conserving energy when forming a negative ion through direct electron attachment the excess energy has to be dissipated through a photon A + e = Amacr + But radiative Capture is rare (5bull10-22cm2 for H2)
Higher cross sections (~10-20cm2 for H2 and Ee gt10 eV) can be realized when the excess energy can be transferred to a third particle M + e = A + B + e and sometimes = A + Bmacr
Cs can be used as an electron donator but the ionisation energy of 39 eV is much higher than the 075 eV electron affinity of H- =gt Surface treatment
Even better are processes which excite a molecule to the edge of breakup (vibrationally excited 4ltnlt12) and then dissociated by a slow electron
Imperial College London 27
Production of negatively charged ion beams
anode
cathode
gasin let solenoid filter
extractore -gtHslow
-driver
e -gtHfast 2
Magnetic dipole fields can be used as filters
to create areas of different electron
temperatures
Cross sections for different production
and destruction mechanisms
Imperial College London 28
Sources using surface production
Schematic layout of the LANCE surface source using a filament driven gas discharge for plasma production and surface conversion on a Cs target for H- formation
Picture of the LANCE surface source
Imperial College London 29
Sources using volume productioncopperm agnetiso latorwater
plasm a-cham ber
plasm a-electrode
screening-e lectrode
electron-dum ping
solenoid bending-m agnet
soleniod
cathodeand
gasin let
filter-m agnet
grid
The small experimental H- source in Frankfurt used a hot cathode driven gas discharge dipole fields and a Pt surface
cover for the reduction of the dissociation of the H2 molecules
Imperial College London 30
Sources using hybrid production schemes
The RAL H- source uses a Penning discharge (dipole for plasma
production and to influence electron temperature) and Cs injection
The SNS H- source developed in Berkley uses RF to produce the plasma dipoles to influence the electron density and a Cs collar
Imperial College London 31
The extraction of particle beams
Imperial College London 32
The space charge limit and Child-Langmuirs law
Imperial College London 33
The space charge limit and Child-Langmuirs law
Imperial College London 34
External and internal fields in the extractor laminar flow and pierce angle
Imperial College London 35
External and internal fields in the extractor laminar flow and pierce angle
Imperial College London 36
The beam emittance the acceptance of the extraction system and the conservation of the phase space
Imperial College London 37
The beam emittance the acceptance of the extraction system and the conservation of the phase space
Imperial College London 38
The beam emittance the acceptance of the extraction system and the conservation of the phase space
Imperial College London 20
Electron Cyclotron Resonance source
By variation of the longitudinal enclosing magnetic mirror configuration the
charge distribution can be influenced
Schematic layout of an ECR source for the production of radioactive
ion beams
Imperial College London 21
Electron Beam Ion Source
nominal valuesmax
valuesunits
electron beam current 350 1300 mA
electron beam energy 20 275 keV
trap length 12 - m
magnetic field 15 5 T
charge per pulse 1-2 4 nC
ion pulse length 005-100 - micros
containment time 20-2000 - ms
Parameters of CRYSIS Upper First EBIS IEL-1 build by Donets in 1968 lower Evolution of charge state distribution of nitrogen ions at Ee=545 keV
17 cm
CRYogenic Stockholm Ion Source
Imperial College London 22
Electron Beam Ion Source
Ion current extracted from an EBIS as a function of the
charge state for Na ions (Ne gas was added)
Comparison of the extractable (electric)
current between ECR and EBIS
Total ion charge trapped in an EBIS as a function of confinement time for different electron beam currents
Imperial College London 23
Laser Ion Sources
Schematic drawing of the experimental set up of a laser ion source By the impact of the laser with the target a plasma is created which expands
in the drift chamber and then is accelerated in the extraction gap
Imperial College London 24
Laser Ion Sources
The different charge states of the plasma are separated by the drift longitudinally and reduce space charge in the acceleration gap
By interaction of the plasma electrons with the electric field of the laser pulse the electrons are heated This leads to a shift of the charge state distribution of the plasma ions towards higher charge states
Imperial College London 25
Laser Ion Sources
The available laser power density on the target (for fixed total laser power influenced by beam size on target) strongly influences the charge state distribution of the plasma
The different charge states of the plasma are separated by the drift longitudinally (higher charge states first) and reduce space charge in the acceleration gap
Imperial College London 26
Production of negatively charged ion beams
Three Types of H- Ion Sources are in use
bull Surface conversion sources
bull Volume production sources
bull Hybrid production sources
Conserving energy when forming a negative ion through direct electron attachment the excess energy has to be dissipated through a photon A + e = Amacr + But radiative Capture is rare (5bull10-22cm2 for H2)
Higher cross sections (~10-20cm2 for H2 and Ee gt10 eV) can be realized when the excess energy can be transferred to a third particle M + e = A + B + e and sometimes = A + Bmacr
Cs can be used as an electron donator but the ionisation energy of 39 eV is much higher than the 075 eV electron affinity of H- =gt Surface treatment
Even better are processes which excite a molecule to the edge of breakup (vibrationally excited 4ltnlt12) and then dissociated by a slow electron
Imperial College London 27
Production of negatively charged ion beams
anode
cathode
gasin let solenoid filter
extractore -gtHslow
-driver
e -gtHfast 2
Magnetic dipole fields can be used as filters
to create areas of different electron
temperatures
Cross sections for different production
and destruction mechanisms
Imperial College London 28
Sources using surface production
Schematic layout of the LANCE surface source using a filament driven gas discharge for plasma production and surface conversion on a Cs target for H- formation
Picture of the LANCE surface source
Imperial College London 29
Sources using volume productioncopperm agnetiso latorwater
plasm a-cham ber
plasm a-electrode
screening-e lectrode
electron-dum ping
solenoid bending-m agnet
soleniod
cathodeand
gasin let
filter-m agnet
grid
The small experimental H- source in Frankfurt used a hot cathode driven gas discharge dipole fields and a Pt surface
cover for the reduction of the dissociation of the H2 molecules
Imperial College London 30
Sources using hybrid production schemes
The RAL H- source uses a Penning discharge (dipole for plasma
production and to influence electron temperature) and Cs injection
The SNS H- source developed in Berkley uses RF to produce the plasma dipoles to influence the electron density and a Cs collar
Imperial College London 31
The extraction of particle beams
Imperial College London 32
The space charge limit and Child-Langmuirs law
Imperial College London 33
The space charge limit and Child-Langmuirs law
Imperial College London 34
External and internal fields in the extractor laminar flow and pierce angle
Imperial College London 35
External and internal fields in the extractor laminar flow and pierce angle
Imperial College London 36
The beam emittance the acceptance of the extraction system and the conservation of the phase space
Imperial College London 37
The beam emittance the acceptance of the extraction system and the conservation of the phase space
Imperial College London 38
The beam emittance the acceptance of the extraction system and the conservation of the phase space
Imperial College London 21
Electron Beam Ion Source
nominal valuesmax
valuesunits
electron beam current 350 1300 mA
electron beam energy 20 275 keV
trap length 12 - m
magnetic field 15 5 T
charge per pulse 1-2 4 nC
ion pulse length 005-100 - micros
containment time 20-2000 - ms
Parameters of CRYSIS Upper First EBIS IEL-1 build by Donets in 1968 lower Evolution of charge state distribution of nitrogen ions at Ee=545 keV
17 cm
CRYogenic Stockholm Ion Source
Imperial College London 22
Electron Beam Ion Source
Ion current extracted from an EBIS as a function of the
charge state for Na ions (Ne gas was added)
Comparison of the extractable (electric)
current between ECR and EBIS
Total ion charge trapped in an EBIS as a function of confinement time for different electron beam currents
Imperial College London 23
Laser Ion Sources
Schematic drawing of the experimental set up of a laser ion source By the impact of the laser with the target a plasma is created which expands
in the drift chamber and then is accelerated in the extraction gap
Imperial College London 24
Laser Ion Sources
The different charge states of the plasma are separated by the drift longitudinally and reduce space charge in the acceleration gap
By interaction of the plasma electrons with the electric field of the laser pulse the electrons are heated This leads to a shift of the charge state distribution of the plasma ions towards higher charge states
Imperial College London 25
Laser Ion Sources
The available laser power density on the target (for fixed total laser power influenced by beam size on target) strongly influences the charge state distribution of the plasma
The different charge states of the plasma are separated by the drift longitudinally (higher charge states first) and reduce space charge in the acceleration gap
Imperial College London 26
Production of negatively charged ion beams
Three Types of H- Ion Sources are in use
bull Surface conversion sources
bull Volume production sources
bull Hybrid production sources
Conserving energy when forming a negative ion through direct electron attachment the excess energy has to be dissipated through a photon A + e = Amacr + But radiative Capture is rare (5bull10-22cm2 for H2)
Higher cross sections (~10-20cm2 for H2 and Ee gt10 eV) can be realized when the excess energy can be transferred to a third particle M + e = A + B + e and sometimes = A + Bmacr
Cs can be used as an electron donator but the ionisation energy of 39 eV is much higher than the 075 eV electron affinity of H- =gt Surface treatment
Even better are processes which excite a molecule to the edge of breakup (vibrationally excited 4ltnlt12) and then dissociated by a slow electron
Imperial College London 27
Production of negatively charged ion beams
anode
cathode
gasin let solenoid filter
extractore -gtHslow
-driver
e -gtHfast 2
Magnetic dipole fields can be used as filters
to create areas of different electron
temperatures
Cross sections for different production
and destruction mechanisms
Imperial College London 28
Sources using surface production
Schematic layout of the LANCE surface source using a filament driven gas discharge for plasma production and surface conversion on a Cs target for H- formation
Picture of the LANCE surface source
Imperial College London 29
Sources using volume productioncopperm agnetiso latorwater
plasm a-cham ber
plasm a-electrode
screening-e lectrode
electron-dum ping
solenoid bending-m agnet
soleniod
cathodeand
gasin let
filter-m agnet
grid
The small experimental H- source in Frankfurt used a hot cathode driven gas discharge dipole fields and a Pt surface
cover for the reduction of the dissociation of the H2 molecules
Imperial College London 30
Sources using hybrid production schemes
The RAL H- source uses a Penning discharge (dipole for plasma
production and to influence electron temperature) and Cs injection
The SNS H- source developed in Berkley uses RF to produce the plasma dipoles to influence the electron density and a Cs collar
Imperial College London 31
The extraction of particle beams
Imperial College London 32
The space charge limit and Child-Langmuirs law
Imperial College London 33
The space charge limit and Child-Langmuirs law
Imperial College London 34
External and internal fields in the extractor laminar flow and pierce angle
Imperial College London 35
External and internal fields in the extractor laminar flow and pierce angle
Imperial College London 36
The beam emittance the acceptance of the extraction system and the conservation of the phase space
Imperial College London 37
The beam emittance the acceptance of the extraction system and the conservation of the phase space
Imperial College London 38
The beam emittance the acceptance of the extraction system and the conservation of the phase space
Imperial College London 22
Electron Beam Ion Source
Ion current extracted from an EBIS as a function of the
charge state for Na ions (Ne gas was added)
Comparison of the extractable (electric)
current between ECR and EBIS
Total ion charge trapped in an EBIS as a function of confinement time for different electron beam currents
Imperial College London 23
Laser Ion Sources
Schematic drawing of the experimental set up of a laser ion source By the impact of the laser with the target a plasma is created which expands
in the drift chamber and then is accelerated in the extraction gap
Imperial College London 24
Laser Ion Sources
The different charge states of the plasma are separated by the drift longitudinally and reduce space charge in the acceleration gap
By interaction of the plasma electrons with the electric field of the laser pulse the electrons are heated This leads to a shift of the charge state distribution of the plasma ions towards higher charge states
Imperial College London 25
Laser Ion Sources
The available laser power density on the target (for fixed total laser power influenced by beam size on target) strongly influences the charge state distribution of the plasma
The different charge states of the plasma are separated by the drift longitudinally (higher charge states first) and reduce space charge in the acceleration gap
Imperial College London 26
Production of negatively charged ion beams
Three Types of H- Ion Sources are in use
bull Surface conversion sources
bull Volume production sources
bull Hybrid production sources
Conserving energy when forming a negative ion through direct electron attachment the excess energy has to be dissipated through a photon A + e = Amacr + But radiative Capture is rare (5bull10-22cm2 for H2)
Higher cross sections (~10-20cm2 for H2 and Ee gt10 eV) can be realized when the excess energy can be transferred to a third particle M + e = A + B + e and sometimes = A + Bmacr
Cs can be used as an electron donator but the ionisation energy of 39 eV is much higher than the 075 eV electron affinity of H- =gt Surface treatment
Even better are processes which excite a molecule to the edge of breakup (vibrationally excited 4ltnlt12) and then dissociated by a slow electron
Imperial College London 27
Production of negatively charged ion beams
anode
cathode
gasin let solenoid filter
extractore -gtHslow
-driver
e -gtHfast 2
Magnetic dipole fields can be used as filters
to create areas of different electron
temperatures
Cross sections for different production
and destruction mechanisms
Imperial College London 28
Sources using surface production
Schematic layout of the LANCE surface source using a filament driven gas discharge for plasma production and surface conversion on a Cs target for H- formation
Picture of the LANCE surface source
Imperial College London 29
Sources using volume productioncopperm agnetiso latorwater
plasm a-cham ber
plasm a-electrode
screening-e lectrode
electron-dum ping
solenoid bending-m agnet
soleniod
cathodeand
gasin let
filter-m agnet
grid
The small experimental H- source in Frankfurt used a hot cathode driven gas discharge dipole fields and a Pt surface
cover for the reduction of the dissociation of the H2 molecules
Imperial College London 30
Sources using hybrid production schemes
The RAL H- source uses a Penning discharge (dipole for plasma
production and to influence electron temperature) and Cs injection
The SNS H- source developed in Berkley uses RF to produce the plasma dipoles to influence the electron density and a Cs collar
Imperial College London 31
The extraction of particle beams
Imperial College London 32
The space charge limit and Child-Langmuirs law
Imperial College London 33
The space charge limit and Child-Langmuirs law
Imperial College London 34
External and internal fields in the extractor laminar flow and pierce angle
Imperial College London 35
External and internal fields in the extractor laminar flow and pierce angle
Imperial College London 36
The beam emittance the acceptance of the extraction system and the conservation of the phase space
Imperial College London 37
The beam emittance the acceptance of the extraction system and the conservation of the phase space
Imperial College London 38
The beam emittance the acceptance of the extraction system and the conservation of the phase space
Imperial College London 23
Laser Ion Sources
Schematic drawing of the experimental set up of a laser ion source By the impact of the laser with the target a plasma is created which expands
in the drift chamber and then is accelerated in the extraction gap
Imperial College London 24
Laser Ion Sources
The different charge states of the plasma are separated by the drift longitudinally and reduce space charge in the acceleration gap
By interaction of the plasma electrons with the electric field of the laser pulse the electrons are heated This leads to a shift of the charge state distribution of the plasma ions towards higher charge states
Imperial College London 25
Laser Ion Sources
The available laser power density on the target (for fixed total laser power influenced by beam size on target) strongly influences the charge state distribution of the plasma
The different charge states of the plasma are separated by the drift longitudinally (higher charge states first) and reduce space charge in the acceleration gap
Imperial College London 26
Production of negatively charged ion beams
Three Types of H- Ion Sources are in use
bull Surface conversion sources
bull Volume production sources
bull Hybrid production sources
Conserving energy when forming a negative ion through direct electron attachment the excess energy has to be dissipated through a photon A + e = Amacr + But radiative Capture is rare (5bull10-22cm2 for H2)
Higher cross sections (~10-20cm2 for H2 and Ee gt10 eV) can be realized when the excess energy can be transferred to a third particle M + e = A + B + e and sometimes = A + Bmacr
Cs can be used as an electron donator but the ionisation energy of 39 eV is much higher than the 075 eV electron affinity of H- =gt Surface treatment
Even better are processes which excite a molecule to the edge of breakup (vibrationally excited 4ltnlt12) and then dissociated by a slow electron
Imperial College London 27
Production of negatively charged ion beams
anode
cathode
gasin let solenoid filter
extractore -gtHslow
-driver
e -gtHfast 2
Magnetic dipole fields can be used as filters
to create areas of different electron
temperatures
Cross sections for different production
and destruction mechanisms
Imperial College London 28
Sources using surface production
Schematic layout of the LANCE surface source using a filament driven gas discharge for plasma production and surface conversion on a Cs target for H- formation
Picture of the LANCE surface source
Imperial College London 29
Sources using volume productioncopperm agnetiso latorwater
plasm a-cham ber
plasm a-electrode
screening-e lectrode
electron-dum ping
solenoid bending-m agnet
soleniod
cathodeand
gasin let
filter-m agnet
grid
The small experimental H- source in Frankfurt used a hot cathode driven gas discharge dipole fields and a Pt surface
cover for the reduction of the dissociation of the H2 molecules
Imperial College London 30
Sources using hybrid production schemes
The RAL H- source uses a Penning discharge (dipole for plasma
production and to influence electron temperature) and Cs injection
The SNS H- source developed in Berkley uses RF to produce the plasma dipoles to influence the electron density and a Cs collar
Imperial College London 31
The extraction of particle beams
Imperial College London 32
The space charge limit and Child-Langmuirs law
Imperial College London 33
The space charge limit and Child-Langmuirs law
Imperial College London 34
External and internal fields in the extractor laminar flow and pierce angle
Imperial College London 35
External and internal fields in the extractor laminar flow and pierce angle
Imperial College London 36
The beam emittance the acceptance of the extraction system and the conservation of the phase space
Imperial College London 37
The beam emittance the acceptance of the extraction system and the conservation of the phase space
Imperial College London 38
The beam emittance the acceptance of the extraction system and the conservation of the phase space
Imperial College London 24
Laser Ion Sources
The different charge states of the plasma are separated by the drift longitudinally and reduce space charge in the acceleration gap
By interaction of the plasma electrons with the electric field of the laser pulse the electrons are heated This leads to a shift of the charge state distribution of the plasma ions towards higher charge states
Imperial College London 25
Laser Ion Sources
The available laser power density on the target (for fixed total laser power influenced by beam size on target) strongly influences the charge state distribution of the plasma
The different charge states of the plasma are separated by the drift longitudinally (higher charge states first) and reduce space charge in the acceleration gap
Imperial College London 26
Production of negatively charged ion beams
Three Types of H- Ion Sources are in use
bull Surface conversion sources
bull Volume production sources
bull Hybrid production sources
Conserving energy when forming a negative ion through direct electron attachment the excess energy has to be dissipated through a photon A + e = Amacr + But radiative Capture is rare (5bull10-22cm2 for H2)
Higher cross sections (~10-20cm2 for H2 and Ee gt10 eV) can be realized when the excess energy can be transferred to a third particle M + e = A + B + e and sometimes = A + Bmacr
Cs can be used as an electron donator but the ionisation energy of 39 eV is much higher than the 075 eV electron affinity of H- =gt Surface treatment
Even better are processes which excite a molecule to the edge of breakup (vibrationally excited 4ltnlt12) and then dissociated by a slow electron
Imperial College London 27
Production of negatively charged ion beams
anode
cathode
gasin let solenoid filter
extractore -gtHslow
-driver
e -gtHfast 2
Magnetic dipole fields can be used as filters
to create areas of different electron
temperatures
Cross sections for different production
and destruction mechanisms
Imperial College London 28
Sources using surface production
Schematic layout of the LANCE surface source using a filament driven gas discharge for plasma production and surface conversion on a Cs target for H- formation
Picture of the LANCE surface source
Imperial College London 29
Sources using volume productioncopperm agnetiso latorwater
plasm a-cham ber
plasm a-electrode
screening-e lectrode
electron-dum ping
solenoid bending-m agnet
soleniod
cathodeand
gasin let
filter-m agnet
grid
The small experimental H- source in Frankfurt used a hot cathode driven gas discharge dipole fields and a Pt surface
cover for the reduction of the dissociation of the H2 molecules
Imperial College London 30
Sources using hybrid production schemes
The RAL H- source uses a Penning discharge (dipole for plasma
production and to influence electron temperature) and Cs injection
The SNS H- source developed in Berkley uses RF to produce the plasma dipoles to influence the electron density and a Cs collar
Imperial College London 31
The extraction of particle beams
Imperial College London 32
The space charge limit and Child-Langmuirs law
Imperial College London 33
The space charge limit and Child-Langmuirs law
Imperial College London 34
External and internal fields in the extractor laminar flow and pierce angle
Imperial College London 35
External and internal fields in the extractor laminar flow and pierce angle
Imperial College London 36
The beam emittance the acceptance of the extraction system and the conservation of the phase space
Imperial College London 37
The beam emittance the acceptance of the extraction system and the conservation of the phase space
Imperial College London 38
The beam emittance the acceptance of the extraction system and the conservation of the phase space
Imperial College London 25
Laser Ion Sources
The available laser power density on the target (for fixed total laser power influenced by beam size on target) strongly influences the charge state distribution of the plasma
The different charge states of the plasma are separated by the drift longitudinally (higher charge states first) and reduce space charge in the acceleration gap
Imperial College London 26
Production of negatively charged ion beams
Three Types of H- Ion Sources are in use
bull Surface conversion sources
bull Volume production sources
bull Hybrid production sources
Conserving energy when forming a negative ion through direct electron attachment the excess energy has to be dissipated through a photon A + e = Amacr + But radiative Capture is rare (5bull10-22cm2 for H2)
Higher cross sections (~10-20cm2 for H2 and Ee gt10 eV) can be realized when the excess energy can be transferred to a third particle M + e = A + B + e and sometimes = A + Bmacr
Cs can be used as an electron donator but the ionisation energy of 39 eV is much higher than the 075 eV electron affinity of H- =gt Surface treatment
Even better are processes which excite a molecule to the edge of breakup (vibrationally excited 4ltnlt12) and then dissociated by a slow electron
Imperial College London 27
Production of negatively charged ion beams
anode
cathode
gasin let solenoid filter
extractore -gtHslow
-driver
e -gtHfast 2
Magnetic dipole fields can be used as filters
to create areas of different electron
temperatures
Cross sections for different production
and destruction mechanisms
Imperial College London 28
Sources using surface production
Schematic layout of the LANCE surface source using a filament driven gas discharge for plasma production and surface conversion on a Cs target for H- formation
Picture of the LANCE surface source
Imperial College London 29
Sources using volume productioncopperm agnetiso latorwater
plasm a-cham ber
plasm a-electrode
screening-e lectrode
electron-dum ping
solenoid bending-m agnet
soleniod
cathodeand
gasin let
filter-m agnet
grid
The small experimental H- source in Frankfurt used a hot cathode driven gas discharge dipole fields and a Pt surface
cover for the reduction of the dissociation of the H2 molecules
Imperial College London 30
Sources using hybrid production schemes
The RAL H- source uses a Penning discharge (dipole for plasma
production and to influence electron temperature) and Cs injection
The SNS H- source developed in Berkley uses RF to produce the plasma dipoles to influence the electron density and a Cs collar
Imperial College London 31
The extraction of particle beams
Imperial College London 32
The space charge limit and Child-Langmuirs law
Imperial College London 33
The space charge limit and Child-Langmuirs law
Imperial College London 34
External and internal fields in the extractor laminar flow and pierce angle
Imperial College London 35
External and internal fields in the extractor laminar flow and pierce angle
Imperial College London 36
The beam emittance the acceptance of the extraction system and the conservation of the phase space
Imperial College London 37
The beam emittance the acceptance of the extraction system and the conservation of the phase space
Imperial College London 38
The beam emittance the acceptance of the extraction system and the conservation of the phase space
Imperial College London 26
Production of negatively charged ion beams
Three Types of H- Ion Sources are in use
bull Surface conversion sources
bull Volume production sources
bull Hybrid production sources
Conserving energy when forming a negative ion through direct electron attachment the excess energy has to be dissipated through a photon A + e = Amacr + But radiative Capture is rare (5bull10-22cm2 for H2)
Higher cross sections (~10-20cm2 for H2 and Ee gt10 eV) can be realized when the excess energy can be transferred to a third particle M + e = A + B + e and sometimes = A + Bmacr
Cs can be used as an electron donator but the ionisation energy of 39 eV is much higher than the 075 eV electron affinity of H- =gt Surface treatment
Even better are processes which excite a molecule to the edge of breakup (vibrationally excited 4ltnlt12) and then dissociated by a slow electron
Imperial College London 27
Production of negatively charged ion beams
anode
cathode
gasin let solenoid filter
extractore -gtHslow
-driver
e -gtHfast 2
Magnetic dipole fields can be used as filters
to create areas of different electron
temperatures
Cross sections for different production
and destruction mechanisms
Imperial College London 28
Sources using surface production
Schematic layout of the LANCE surface source using a filament driven gas discharge for plasma production and surface conversion on a Cs target for H- formation
Picture of the LANCE surface source
Imperial College London 29
Sources using volume productioncopperm agnetiso latorwater
plasm a-cham ber
plasm a-electrode
screening-e lectrode
electron-dum ping
solenoid bending-m agnet
soleniod
cathodeand
gasin let
filter-m agnet
grid
The small experimental H- source in Frankfurt used a hot cathode driven gas discharge dipole fields and a Pt surface
cover for the reduction of the dissociation of the H2 molecules
Imperial College London 30
Sources using hybrid production schemes
The RAL H- source uses a Penning discharge (dipole for plasma
production and to influence electron temperature) and Cs injection
The SNS H- source developed in Berkley uses RF to produce the plasma dipoles to influence the electron density and a Cs collar
Imperial College London 31
The extraction of particle beams
Imperial College London 32
The space charge limit and Child-Langmuirs law
Imperial College London 33
The space charge limit and Child-Langmuirs law
Imperial College London 34
External and internal fields in the extractor laminar flow and pierce angle
Imperial College London 35
External and internal fields in the extractor laminar flow and pierce angle
Imperial College London 36
The beam emittance the acceptance of the extraction system and the conservation of the phase space
Imperial College London 37
The beam emittance the acceptance of the extraction system and the conservation of the phase space
Imperial College London 38
The beam emittance the acceptance of the extraction system and the conservation of the phase space
Imperial College London 27
Production of negatively charged ion beams
anode
cathode
gasin let solenoid filter
extractore -gtHslow
-driver
e -gtHfast 2
Magnetic dipole fields can be used as filters
to create areas of different electron
temperatures
Cross sections for different production
and destruction mechanisms
Imperial College London 28
Sources using surface production
Schematic layout of the LANCE surface source using a filament driven gas discharge for plasma production and surface conversion on a Cs target for H- formation
Picture of the LANCE surface source
Imperial College London 29
Sources using volume productioncopperm agnetiso latorwater
plasm a-cham ber
plasm a-electrode
screening-e lectrode
electron-dum ping
solenoid bending-m agnet
soleniod
cathodeand
gasin let
filter-m agnet
grid
The small experimental H- source in Frankfurt used a hot cathode driven gas discharge dipole fields and a Pt surface
cover for the reduction of the dissociation of the H2 molecules
Imperial College London 30
Sources using hybrid production schemes
The RAL H- source uses a Penning discharge (dipole for plasma
production and to influence electron temperature) and Cs injection
The SNS H- source developed in Berkley uses RF to produce the plasma dipoles to influence the electron density and a Cs collar
Imperial College London 31
The extraction of particle beams
Imperial College London 32
The space charge limit and Child-Langmuirs law
Imperial College London 33
The space charge limit and Child-Langmuirs law
Imperial College London 34
External and internal fields in the extractor laminar flow and pierce angle
Imperial College London 35
External and internal fields in the extractor laminar flow and pierce angle
Imperial College London 36
The beam emittance the acceptance of the extraction system and the conservation of the phase space
Imperial College London 37
The beam emittance the acceptance of the extraction system and the conservation of the phase space
Imperial College London 38
The beam emittance the acceptance of the extraction system and the conservation of the phase space
Imperial College London 28
Sources using surface production
Schematic layout of the LANCE surface source using a filament driven gas discharge for plasma production and surface conversion on a Cs target for H- formation
Picture of the LANCE surface source
Imperial College London 29
Sources using volume productioncopperm agnetiso latorwater
plasm a-cham ber
plasm a-electrode
screening-e lectrode
electron-dum ping
solenoid bending-m agnet
soleniod
cathodeand
gasin let
filter-m agnet
grid
The small experimental H- source in Frankfurt used a hot cathode driven gas discharge dipole fields and a Pt surface
cover for the reduction of the dissociation of the H2 molecules
Imperial College London 30
Sources using hybrid production schemes
The RAL H- source uses a Penning discharge (dipole for plasma
production and to influence electron temperature) and Cs injection
The SNS H- source developed in Berkley uses RF to produce the plasma dipoles to influence the electron density and a Cs collar
Imperial College London 31
The extraction of particle beams
Imperial College London 32
The space charge limit and Child-Langmuirs law
Imperial College London 33
The space charge limit and Child-Langmuirs law
Imperial College London 34
External and internal fields in the extractor laminar flow and pierce angle
Imperial College London 35
External and internal fields in the extractor laminar flow and pierce angle
Imperial College London 36
The beam emittance the acceptance of the extraction system and the conservation of the phase space
Imperial College London 37
The beam emittance the acceptance of the extraction system and the conservation of the phase space
Imperial College London 38
The beam emittance the acceptance of the extraction system and the conservation of the phase space
Imperial College London 29
Sources using volume productioncopperm agnetiso latorwater
plasm a-cham ber
plasm a-electrode
screening-e lectrode
electron-dum ping
solenoid bending-m agnet
soleniod
cathodeand
gasin let
filter-m agnet
grid
The small experimental H- source in Frankfurt used a hot cathode driven gas discharge dipole fields and a Pt surface
cover for the reduction of the dissociation of the H2 molecules
Imperial College London 30
Sources using hybrid production schemes
The RAL H- source uses a Penning discharge (dipole for plasma
production and to influence electron temperature) and Cs injection
The SNS H- source developed in Berkley uses RF to produce the plasma dipoles to influence the electron density and a Cs collar
Imperial College London 31
The extraction of particle beams
Imperial College London 32
The space charge limit and Child-Langmuirs law
Imperial College London 33
The space charge limit and Child-Langmuirs law
Imperial College London 34
External and internal fields in the extractor laminar flow and pierce angle
Imperial College London 35
External and internal fields in the extractor laminar flow and pierce angle
Imperial College London 36
The beam emittance the acceptance of the extraction system and the conservation of the phase space
Imperial College London 37
The beam emittance the acceptance of the extraction system and the conservation of the phase space
Imperial College London 38
The beam emittance the acceptance of the extraction system and the conservation of the phase space
Imperial College London 30
Sources using hybrid production schemes
The RAL H- source uses a Penning discharge (dipole for plasma
production and to influence electron temperature) and Cs injection
The SNS H- source developed in Berkley uses RF to produce the plasma dipoles to influence the electron density and a Cs collar
Imperial College London 31
The extraction of particle beams
Imperial College London 32
The space charge limit and Child-Langmuirs law
Imperial College London 33
The space charge limit and Child-Langmuirs law
Imperial College London 34
External and internal fields in the extractor laminar flow and pierce angle
Imperial College London 35
External and internal fields in the extractor laminar flow and pierce angle
Imperial College London 36
The beam emittance the acceptance of the extraction system and the conservation of the phase space
Imperial College London 37
The beam emittance the acceptance of the extraction system and the conservation of the phase space
Imperial College London 38
The beam emittance the acceptance of the extraction system and the conservation of the phase space
Imperial College London 31
The extraction of particle beams
Imperial College London 32
The space charge limit and Child-Langmuirs law
Imperial College London 33
The space charge limit and Child-Langmuirs law
Imperial College London 34
External and internal fields in the extractor laminar flow and pierce angle
Imperial College London 35
External and internal fields in the extractor laminar flow and pierce angle
Imperial College London 36
The beam emittance the acceptance of the extraction system and the conservation of the phase space
Imperial College London 37
The beam emittance the acceptance of the extraction system and the conservation of the phase space
Imperial College London 38
The beam emittance the acceptance of the extraction system and the conservation of the phase space
Imperial College London 32
The space charge limit and Child-Langmuirs law
Imperial College London 33
The space charge limit and Child-Langmuirs law
Imperial College London 34
External and internal fields in the extractor laminar flow and pierce angle
Imperial College London 35
External and internal fields in the extractor laminar flow and pierce angle
Imperial College London 36
The beam emittance the acceptance of the extraction system and the conservation of the phase space
Imperial College London 37
The beam emittance the acceptance of the extraction system and the conservation of the phase space
Imperial College London 38
The beam emittance the acceptance of the extraction system and the conservation of the phase space
Imperial College London 33
The space charge limit and Child-Langmuirs law
Imperial College London 34
External and internal fields in the extractor laminar flow and pierce angle
Imperial College London 35
External and internal fields in the extractor laminar flow and pierce angle
Imperial College London 36
The beam emittance the acceptance of the extraction system and the conservation of the phase space
Imperial College London 37
The beam emittance the acceptance of the extraction system and the conservation of the phase space
Imperial College London 38
The beam emittance the acceptance of the extraction system and the conservation of the phase space
Imperial College London 34
External and internal fields in the extractor laminar flow and pierce angle
Imperial College London 35
External and internal fields in the extractor laminar flow and pierce angle
Imperial College London 36
The beam emittance the acceptance of the extraction system and the conservation of the phase space
Imperial College London 37
The beam emittance the acceptance of the extraction system and the conservation of the phase space
Imperial College London 38
The beam emittance the acceptance of the extraction system and the conservation of the phase space
Imperial College London 35
External and internal fields in the extractor laminar flow and pierce angle
Imperial College London 36
The beam emittance the acceptance of the extraction system and the conservation of the phase space
Imperial College London 37
The beam emittance the acceptance of the extraction system and the conservation of the phase space
Imperial College London 38
The beam emittance the acceptance of the extraction system and the conservation of the phase space
Imperial College London 36
The beam emittance the acceptance of the extraction system and the conservation of the phase space
Imperial College London 37
The beam emittance the acceptance of the extraction system and the conservation of the phase space
Imperial College London 38
The beam emittance the acceptance of the extraction system and the conservation of the phase space
Imperial College London 37
The beam emittance the acceptance of the extraction system and the conservation of the phase space
Imperial College London 38
The beam emittance the acceptance of the extraction system and the conservation of the phase space
Imperial College London 38
The beam emittance the acceptance of the extraction system and the conservation of the phase space