Painting, injection matching, emittances and beam dynamics

Painting, injection matching, emittances and beam dynamics

C. Bracco, C. Carli, L. M. Coralejo Feliciano, L. Ducimetiere, T. Fowler, B. Goddard, G. Grawer, J-B. Lallement, B. Mikulec, M. Scholz, W. Weterings

Outlines• H- charge exchange injection: principle and layout (chicane + stripping foil)

• Injection painting in phase space– Longitudinal – Transversal (horizontal plane, KSW magnets)

• Studies for HW specifications

• Vertical Plane

• Conclusions

H- Injection

• Beam injected in with 66mrad angle w.r.t. PSB axis• Strength of BS chicane magnets maximum during injection 45.9 mm orbit

bump • Chicane decays after Injection• Edge focusing effects at the pole faces Strong vertical β-beating• Solutions :

– Passive compensation: pole face rotation – Active compensation: additional trim quadrupoles (5 ms chicane decay)

more flexible, better compensation & lower losses (<5%)

Longitudinal painting Attenuation of space charge effects can be obtained by controlling the distribution,

in phase space of injected particles Energy of the injected beam will be varied to fill the bucket with an equal density

distribution.

±1.1 MeV energy distribution over a period of 40 turns

Transverse Painting Scheme• Horizontal painting bump implemented• Fill first the centre and then the outer area of the ellipse in the transverse phase

space• Decay time modulation of four kicker magnets (KSW), installed in the PSB lattice,

allow to accomplish transverse phase space painting to required emittance.• Maximum height of the bump, at injection, depends on the beam and injection

parameters

Injected Beam

Xoff (t1)

Xoff,max

Effect of Stripping Foil on Emittance

• Beam injected over 40 turns (LHC beam)• Particle distribution generated for a horizontal position of -35mm (0 offset applied), matched in

dispersion (Dx = -1.4 m)• Bump height is kept fixed at -35mm over 100 turns• Circulating beam passes through the stripping foil at each turn• Horizontal emittance increases linearly after injection is finished a factor of 2 increase after 100

turns• Need for horizontal painting to move beam off foil!

End of injection!

Different Beams Required by Users

User Description Intensity per ring [p+]

Norm. Emittance [mm mrad]H V

LHC25 25ns LHC beam 3.25×1012 2.5 2.5CNGS CNGS target 6.00×1011

8.00×101210 8

SFTPRO SPS fixed target 6.00×1012 8 6AD AD target 4.00×1012 8 6

nTOF nTOF beam 9.00×1012 10 10NORMGPSNORMHRS

ISOLDE GPS/HRS target beams

1.00×1013 15 9

STAGISO ISOLDE special targets 3.50×1012 8 4

Multi-turn injection

KSW modulations and different number of turns to reach target emittances with uniform particle distribution.

ORBIT Simulations• Simulations were performed with the particle tracking code ORBIT

• H- charge exchange, space charge effects, apertures and accelerations are included

• A routine, implemented in ORBIT, allows to simulate the painting bump (KSW thin lens approximation)

• Initial 6D distribution generated with a “Mathematica” notebook – longitudinal painting is included (500 000 macroparticles)

• Initial lattice generated with MAD8 – Lattice stays unchanged during injection – After injection, lattice has to be reloaded at each turn to simulate chicane fall

Multi-Linear Decay Waveform for KSW

Time [us] t2tfall

KSW

Str

ength

t1

Imax

I1I2

Imax: current corresponding to 35 mm orbit Faster decay to I1 until t1 followed by an almost constant slope until t2 more uniform charge distribution: lower density in the core Fast decay to 0 current to move the beam away from the stripping foil (maximum achievable gradient Imax I0 = 15 ms)

User # turns I1 [% Imax] I2 [% Imax] t1 t2 tfall const Vert offsetLHC25 40 90 89 10 40 55 3.5CNGS 40 68 67 15 40 55 7

SFTPRO 40 70 69 22 40 55 6AD 40 70 69 22 40 55 6.5TOF 40 68 67 15 40 55 8

NORMGPS 40 60 59 12 40 55 7.5NORMHRS STAGISO 40 70 69 22 40 55 5

To get 35 mm orbit at stripping foil

kick [mrad] B [T] Gap [mm] NI [A]KSW16L1 5.56 0.029 132 3.01E+03KSW16L4 1.62 0.008 132 8.69E+02KSW1L4 1.62 0.008 132 8.69E+02KSW2L1 5.56 0.029 132 3.01E+03

Waveform Parameters for PSB Users

Imax

• Up to nominal LINAC 4 pulse (1×1014 ppp, 4×10-4 s)• > 40 turns injection (RF)• Matched dispersion Dx = -1.4 m

Vertical offset (steering magnets in TL, see C. Carli’s talk)

Constant fall time: 15 ms (can be as fast as allowed by the hardware)

See L.M. Coralejo Feliciano’s talk


SFTPRO 74 74 73 20 74 89 6AD 50 72 71 20 50 65 6.5TOF 110 71 70 25 110 125 8

NORMGPS 124 64 63 24 124 139 7.5NORMHRS STAGISO 44 70 69 20 44 59 5

Waveform Parameters for PSB Users

• Assuming 8.13×1010 p+/turn (LHC beam type for all users) • Matched dispersion Dx = -1.4 m


SFTPRO 74 76 75 20 74 89 6AD 50 73 72 20 50 65 6.5TOF 110 73 72 25 110 125 8

NORMGPS 124 65 64 24 124 139 7.5NORMHRSSTAGISO 44 73 72 20 44 59 5

• Assuming 8.13×1010 p+/turn (LHC beam type for all users) • Mis-matched dispersion Dx = 0 m

Pulse length of BI.DIS > 100 ms !!

Dx = 0 smaller foil size smaller number of p+ hits

12

Normalized Horizontal Emittance

09/11/2011 Review on PSB 160 MeV H- Injection

• 8.13×1010 p+/turn (LHC beam type for all users)

13

Normalized Vertical Emittance



14

Charge Distribution in Space


NORM


15

Intensity: p+ injected per Turn


TOF NORM

Injection of a reduced intensity over a bigger number of turns:

allows to have a more uniform particle distribution smaller space charge effect Increases the number of foil hits per p+ by a factor ~3 is foil heating a problem?

Betatron Mismatch in Vertical Plane

newyt

yy yt

yyt

newyty

newyyt

yty

y ytyyt

2

H1

2new new

1

2H 1 H 1

new1

2yt 2

1

2

Twiss parameters @ end of TL Twiss parameters @ PSB injection point

Mismatch factor

Final Emittance

17

Pure Betatron Mismatch


• PSB injection point: by=3.7m, ay=0

• End of TL: eyt = 0.8 mm*mrad, ayt=0.04

Theoretical curve

Simulations results*

18

Pure Betatron Mismatch


• PSB injection point: by=3.7m, ay=0

• End of TL: eyt = 0.8 mm*mrad, , ayt=0.04

Theoretical curve

Simulations results*

Highly peaked distribution to be combined with offset

Vertical Painting ?Vertical Offset

[mm] BR1.DVT16L1

[rad] BR1.DVT2L4

[rad] BR1.DVT3L4

[rad]BR1.VVS2L1

[rad]

3.5 8.878e-04 6.061e-05 -4.103e-06 8.175e-04

5 1.268e-03 8.659e-05 -5.861e-06 1.168e-03

6.5 1.648e-03 1.126e-04 -7.619e-06 1.518e-03

7.5 1.902e-03 1.299e-04 -8.791e-06 1.752e-03

8 2.029e-03 1.386e-04 -9.377e-06 1.869e-03

9 2.283e-03 1.559e-04 -1.055e-05 2.102e-03

Foil

3 existing PSB kickers

1 new kicker (3 m downstream of KSW.2L1)

Kick [mrad

]

Length [mm]

B[mT]

BR1.DVT16L1 2.53 403 1.94

BR1.DVT2L4 1.73 403 1.32

BR1.DVT3L4 -1.17 403 0.90

BR1.VVS2L1 2.33 403 1.78

10 mm bump at the stripping foil

Other option:Fast Kicker in the injection line ?

20

Conclusions • A new injection system implemented for injection into PSB from LINAC4• Longitudinal painting: RF limitations minimum number of injection turns = 40• Transverse horizontal painting needed for uniform distribution and to move the

beam off the stripping foil reduce emittance blowup and foil heating• KSW multi-linear waveforms defined for all users and different conditions:

dispersion, number of protons injected per turn HW specifications• A lower injection intensity allows a more uniform particle distribution but

increases the number of foil hits per p+ and requires a longer BI.DIS pulse • Vertical plane:

– offset via steering magnet in TL target emittances and uniform distributions– Betatron mismatch target emittances but peaked distribution (combined with offset?)– Painting in vertical plain would require new hardware (either in the PSB or in the TL), up to now it

doesn’t seem necessary

• Performance for very small emittance LHC beams, in the light of 2011 LHC operation, has still to be evaluated


Documents

Painting, injection matching, emittances and beam dynamics