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The Design Study of Superconducting Magnet System for a Advanced ECR Ion Source
*E-mail : [email protected]
ByoungSeob Lee*, MiSook Won*, JinYong Park*, DongJun Park*, JongPil Kim*, JangHee Yoon*, JongSeong Bae*, JungKeun Ahn*** Korea Basic Science Institute - Busan Center, **Pusan National University
Abstract
The Korea Basic Science Institute is developing a superconducting magnet
system for 28 GHz Electron Cyclotron Resonance Ion Source (ECRIS). We are
investigating in order to realize compact size, economic operation and generation
of high current beam. Although companies and researchers have valuable
experience, skill and ability in designing of superconducting magnet for ECRIS,
they did not exactly proposed a excellent superconducting magnet system for
ECRIS because many superconducting magnets were not required. Of course
they do if we required many magnets for the various application of ECRIS. In
this presentation, we have filed reports of former researcher and we have
discussed the realization of ECRIS over 35 GHz.
Chamber Diameter 150mmlength 500mm
Binj~4T,Bmin~0~1T,Bext~2TRF28GHz(10kWmax)
Chamber Diameter 126mmlength 1000mm
Binj~3.7T, Bext~2.2TRF28GHz(10kWmax)
Lanzhou (China)
Chamber Diameter 150mmlength 500mm
Binj~3.5T, Bmin~0.8T Bext~2TRF28GHz(10kWmax)
RIKEN RIBF (Japan)
FRIB (USA)
VENUS
SC-ECR
SECRAL
Chamber Diameter 180mmlength 650mm
Binj~4.5T,Bext~3.2TRF28GHz(10kWmax)
MS-ECRIS
INFN-LNS (Italy)
KBSI-Busan Center (Korea)
28 GHz ECRIS in The World
Chamber Diameter 150mmlength 500mm
Binj~3.5T,Bmin~0.4~0.8T,Bext~2TRF28GHz(10kWmax)
Large ECR Zone
Low X-ray Heat Load
Critical Problems of ECRIS Magnet
v X-ray Irradiation§ Large Heat Source of Magnet§ Degradation, Erosion
v Critical Current & Field of Superconducting Wire§ HTS Wire§ Nb3Sn LTS Wire§ Hybrid Magnet
v Reinforcement of Structural Strength for Hexapole Magnet§ Liquid Metal§ Special Structure
v Cooling Method§ Recondensed Cooling Method ;
Low Temperature§ Conduction Cooled Method ;
Simple
36GHz ECRIS
Required magnetic field strength
Binj ~5TBr ~2.7TBext ~2.7TBmin 0.8~1.2T
From material of Talks with Dr. Nakagawa
KBSI 28 GHz ECR Ion SourceBmin ; 0.4 ~ 0.8 × Becr T
Rev. Sci. Instrum. 79(2008)033302 D. Leitner et al,
0.55 Tesla
Heat Load & X-ray irradiation
TrapCAD simulation for electrons Calculation X-ray Energy
WWPP SUSAl
correctedSUSAl5
8
13
8,
1,, 1076.11016.1
1004.21016.1
--
-
- ´=´´
=´
=
2620mm
1,,
,872
2
1016.11063.8
1)2620(4
1
correctedSUSAl
SUSAl
PP
mmmm
=´=´
= -
p
Collimator block ; 1 mm2
(Leitner, 2008)
Ref. : First Results for the 28GHz Operation of the superconducting ECRIS VENUS (Leitner, 2004)
0 100 200 300 400 500 600
2.0x104
4.0x104
6.0x104
8.0x104
1.0x105
I (c
ounts
/600 s
eco
nds)
Photon Energy (keV)Energy (keV)
VENUS 28GHz ECRIS Bremsstrahlung Energy Rate
No attenuation
9.6 mm Aluminum4.8 mm Stainless Steel
9.6 mm Aluminum4.8 mm Stainless Steel1.0 mm Tungsten
Energy rate, PAl,SUS = 766000 keV/600s = 1277 keV/s= 1.277 x 106 eV/s= 2.04 x 10-13 J/s= 2.04 x 10-13 W
(∵ 1.6 x 10-19 J = 1 eV)
Bremsstrahlung heating rate = 2W
(Leitner, 2006)
140 mm
500 mm
17 mm 14 mm
Total surface area of plasma chamber:π(702-42)+π(702-7.52)+2π·70·500 = 250,470 (mm2)
Active surface area for bremsstrahlung: π(72-42) = 104 (mm2)
Active surface ratio:2,1,,
1,,41015.4250470
104
correctedcorrectedSUSAl
correctedSUSAl
PP
=´= -
WWPP correctedSUSAl
correctedcorrectedSUSAl2
4
5
41,,
2,1,, 1024.41015.4
1076.11015.4
--
-
- ´=´´
=´
=
0.2 deg
2. X-Ray Energy Rate from Bremsstrahlung spectrum of VENUS
1) Energy rate, PAl,SUS = 766000 keV/600s = 2.04 x 10-13 W2) Energy rate corrected by solid angle
3) Energy rate corrected by solid angle and surface area
WWPP correctedSUSAl
correctedcorrectedSUSAl2
4
5
41,,
2,1,, 1024.41015.4
1076.11015.4
--
-
- ´=´´
=´
=
1. Bremsstrahlung heating rate = 2W
%21022
1024.4 22
=´=´ -
-
3. Energy rate difference
WWPP SUSAl
correctedSUSAl5
8
13
8,
1,, 1076.11016.1
1004.21016.1
--
-
- ´=´´
=´
=
0 100 200 300 400 500 600 70010-2
10-1
100
101
102
103
104
105
10-2
10-1
100
101
102
103
104
105
I (co
unts
/600
sec
onds
)
Photon Energy (keV)
m/r
(cm
2 /g)
Al 2mmWater 2mmAl 2mmTa ?mm
X-ray
xo
meII m-=
Absorption equation
xoeI
)/( rm-=
water
Al
Ta
I0IAl,water,Al
IAl,water,Al, Ta 1mmIAl,water,Al, Ta 2mm
IAl,water,Al, Ta 3mm
Reducing factor
IIRF 0=
1.162683396663850
,, ==AlwaterAlRF
5.224934796268339
1, ==mmTaRF
5.413960186268339
2, ==mmTaRF
1.78797066268339
3, ==mmTaRF
Calculation Concept of X-ray ShieldCalculation Concept of X-ray Shield
Energy (keV)
Experimental data Theoretical data
No attenuation
9.6 mm Aluminum4.8 mm Stainless Steel
9.6 mm Aluminum4.8 mm Stainless Steel1.0 mm Tungsten
Reducing factor of W1mm = 4.5 Reducing factor of W1mm = 2.2
,9.135460316663580
, ==SUSAlRF 2.216216333546031
,, ==WSUSAlRF
0 100 200 300 400 500 600100
101
102
103
104
105
I (c
ounts
/600 s
eco
nds)
Photon Energy (keV)
Calculating the Thickness of X-ray shielding material for KBSI 28GHz ECRIS
1. When Bmin/Becr = 0.45 or 0.5,1) Bremsstrahlung heating from VENIUS data of Fig. 5 in Leitner et al. (2004)
~ 1W/kW of 28GHz rf at no attenuation~ 6W/6kW of 28GHz rf at no attenuation
2) Using 2-mm-thick Ta tube, reducing factor for x-ray, RF ~ 4.53) With 2-mm-thick Ta tube, the final bremsstrahlung heating
~ 0.2W/kW of 28GHz rf~ 1.3W/6kW of 28GHz rf
4) The limit of heat loading by bremsstrahlung for KBSI 28GHz ECRIS, ~ 3W5) Therefore, 2-mm-thick Ta tube is O.K. in operating 6kW of 28GHz rf.
2. When Bmin/Becr = 0.64,
1) Bremsstrahlung heating from VENIUS data of Fig. 11 in Leitner et al. (2008)~ 10W/kW of 28GHz rf at no attenuation~ 60W/6kW of 28GHz rf at no attenuation
2) Using 6.5/5.4-mm-thick Ta/W tube, reducing factor for x-ray, RFTa/W ~ 19Using 4-mm-thick Al tube, 2-mm-thick water and 6.5/5.4-mm-thick Ta/W tube,total reducing factor for x-ray, RFAl,water,Ta/W ~ 20
3) With 6.5/5.4-mm-thick Ta/W tube in our system, the final bremsstrahlung heating~ 0.5W/kW of 28GHz rf~ 3W/6kW of 28GHz rf
4) The limit of heat loading by bremsstrahlung for KBSI 28GHz ECRIS, ~ 3W5) Therefore, we need 6.5 or 5.4-mm-thick Ta or W tube in operating 6kW of 28GHz rf.
Theoretical data with W
No attenuation
4 mm Aluminum2 mm water
4 mm Aluminum2 mm water2 mm Tungsten
Reducing factor of W5.4mm = 18.9
,1.162683396663850
, ==waterAlRF 9.18332311
62683394.5, ==mmWRF
4 mm Aluminum2 mm water5.4 mm Tungsten
Theoretical data with Ta
No attenuation
4 mm Aluminum2 mm water
4 mm Aluminum2 mm water2 mm Tantalum
Reducing factor of Ta6.5mm = 19
,1.162683396663850
, ==waterAlRF 193302786268339
5.6, ==mmTaRF
4 mm Aluminum2 mm water6.5 mm Tantalum
0 100 200 300 400 500 600100
101
102
103
104
105
I (co
unts
/600 s
eco
nds)
Photon Energy (keV)0 100 200 300 400 500 600
100
101
102
103
104
105
I (co
unts
/600 s
eco
nds)
Photon Energy (keV)
LHe no Boil off Cryostat
Spec. Unit ValueWeight of Cryostat(without iron york) kg <1500
Vacuum Rate of Cryostat torr <~9x10-5He Leak Rate of Cryostat cc.atm/sec <~9x1-09
Volume of LHe Vessel liter <950
Cooler Capacity (4ea) First Stage (50K) W 200Second Stage (4.2K) W 6
Number of 4.2K Cooler Port ea 4Number of HTS 500A Current Lead pair 4
Shield Radiation 35Current Lead (4pair)
Conduction 80
Access Port Conduction 5Access Port Radiation 3
Support (8ea)Conduction 3
Total Heat Loss of Thermal Shield < 126 W
LHe Vessel Radiation 0.3HTS Current Lead(4pair) Conduction 0.5
Access Port Conduction 0.4Access Port Radiation 0.2
Support (8ea)Conduction 0.2
X-ray Heating 3 WTotal Heat at Loss of
LHe Vessel < 4.6 W
Reinforced Hexapole Coil Structure
ECR Ion SourceControl System
2.45 GHz ECR Ion Source
X-ray &Beam CurrentMeasurementSystem
ExchangeableECR Ion Source Chamber
X-rayDetector System
Prototype ECR Ion Source System
ECR plasma marks in Plasma chamber
Energy calibration
133Ba
137Cs
60Co
-80 -60 -40 -20 0 20 40 60 80 100
-14
-13
-12
-11
-10
-9
-8
-7
Iprobe-Isat
Te
esat
ModelNewFunction4 (User)
Equation y =m*x + b
Reduced Chi-Sqr
0.04769
Adj. R-Square 0.80732Value Standard Err
D m 0.11069 0.01173D b -9.7069 0.04656
ModelNewFunction4 (User)
Equation y =m*x + b
Reduced Chi-Sqr
1.30947E-5
Adj. R-Squa 0.99881Value Standard Er
D m 0.0116 2.84309E-4
D b -7.972 0.02024
curre
nt (l
nA)
voltage(V)
Electron Temperature = 9.09eV.
ECR Plasma Density 1.235*1011Cm-3
- Langmuir system & experimentation of Prototype
SIMS Depth Profiling of Ar implanted Si
0 50 100 150 200 2501018
1019
1020
1021
1022
1x1023 Ar
Conc
entra
tion(
atom
s/cc
)
Sputter Depth(nm)
100
101
102
103
104
105
106
107 Si O
In
tens
ity(c
ount
s/se
c)
0 50 100 150 200 2501018
1019
1020
1021
1022
1x1023 Ar
Conc
entra
tion(
atom
s/cc
)
Sputter Depth(nm)
100
101
102
103
104
105
106
107 Si O
In
tens
ity(c
ount
s/se
c)
Fig.1 Depth Profile of #0.5kV Sample Fig.2 Depth Profile of #1.5kV Sample
- Implantation of Ar in B-doped SiO2/Si silicon wafer
- The main heat load of superconducting magnet system for ECR ions source
generated by x-ray irradiation.
- The estimation method of x-ray was presented.
- The x-ray heat load for 28GHz ECR ion source was estimated.
- The heat load of magnet system was calculated and The conceptual cooling
system was designed.
- Also, we were trying the study about reinforced structural system and some
basic experiments were performed.
Concluding Remark
MOPOT15