Construction of a 3.9 GHz Superconducting RF Cavity Module ...
IHEP 1.3 GHz 9-cell Cavity R&D Status and Plan
description
Transcript of IHEP 1.3 GHz 9-cell Cavity R&D Status and Plan
IHEP 1.3 GHz 9-cell Cavity
R&D Status and Plan
GAO Jie, ZHAI Jiyuan, YU Jing, LI Zhongquan, ZHAO Tongxian, ZHANG Jingru
Institute of High Energy Physics, Chinese Academy of Sciences
CHEN Jinzhe, QIAO Jianqiang
Beijing Hejieli Science and Technology Development Co. Ltd.
YUAN Hong, YU Huai, WANG Jinxue
Beijing Institute of Aviation Materials
2nd Workshop of the IHEP 1.3 GHz SRF R&D Project
& 2nd IHEP-KEK 1.3 GHz SRF Meeting
Dec.2, 2009, IHEP, Beijing
Outline
• Cavity R&D Goals and the Overall Schedule
• 9-cell Cavity with Bare Tubes (IHEP-01)
– Fabrication and Tuning Procedure
– Surface Treatment and Vertical Test Plan
• 9-cell Cavity with Full End Groups (IHEP-02)
– Design & Fabrication Consideration and Progress
Dec.2, 2009 Jiyuan Zhai, 2nd Workshop of the IHEP 1.3 GHz SRF R&D Project 2
9-cell Cavity R&D Goals
• Demonstrate the common technique for 1.3 GHz multi-
cell cavity fabrication and surface treatment– cavity shape, Nb material; cavity fabrication, EBW, tuning– surface treatment recipes and facilities
• Make two 9-cell cavities– one bare tube– one with full end groups, for the horizontal test
• Achieve the requirement of XFEL-ERL and ILC– 25 - 35 MV / m for the vertical test– 20 - 31.5 MV / m for the horizontal test
– Q0, HOM damping, Lorentz force detuning
Dec.2, 2009 Jiyuan Zhai, 2nd Workshop of the IHEP 1.3 GHz SRF R&D Project 3
9-cell Cavity Overall Schedule
Cavity Duration 2009 2010 2011
IHEP-01 2009-2010
fabrication 2009.2-12
1st test loop 2010.1-4
2nd test loop 2010.5-7
IHEP-02 2010-2011
fabrication 2010.1-7
1st test loop 2010.8-10
2nd test loop 2010.11-12
weld helium vessel 2011.1-3
assemble and HT 2011.6-12?
Dec.2, 2009 Jiyuan Zhai, 2nd Workshop of the IHEP 1.3 GHz SRF R&D Project 4
20 MV/m
25 MV/mS0
25 MV/mS0
HT: horizontal test; S0: ILC R&D task force for high gradient cavities
One test loop includes: surface treatment, pretuning, vertical test and inspection at IHEP or/and KEK
2~4 vertical tests at KEK STF in 2010
Outline
• Cavity R&D Goals and the Overall Schedule
• 9-cell Cavity with Bare Tubes (IHEP-01)– Fabrication and Tuning Procedure
– Surface Treatment and Vertical Test Plan
• 9-cell Cavity with Full End Groups (IHEP-02)– Design & Fabrication Consideration and Progress
Dec.2, 2009 Jiyuan Zhai, 2nd Workshop of the IHEP 1.3 GHz SRF R&D Project 5
Bare Tube 9-cell Cavity (IHEP-01)
• inner cell similar to the original Low Loss shape (iris 60, beam tube 80)
• end cell design without HOM consideration• stiffening ring position same with the ICHIRO cavity• end plates and end stiffening rings to strengthen the end cell• beam tubes length, flanges and input coupler (evacuation) port same
with the STF baseline cavity
Dec.2, 2009 Jiyuan Zhai, 2nd Workshop of the IHEP 1.3 GHz SRF R&D Project 6
Large Grain Niobium
• disks from Ningxia OTIC (72 pieces, Sept.- Nov., 2008)• inspection, CP, annealing• ultrasonic and eddy current scanning tests (YU Jing)• mechanical behavior sample test at room temp. and 4K (MEN Lingling)• RRR measurement (sample before and after EBW) is planned (YU Jing)
Dec.2, 2009 Jiyuan Zhai, 2nd Workshop of the IHEP 1.3 GHz SRF R&D Project 7
Fabrication Procedure• Half cells fabrication (2009.2-5)
1. deep drawing, iris coining, trimming (L= Lnom+ΔLiris+ΔLequ+ΔLtuning)2. CMM dimension check, equator roundness reshaping3. degreasing(micro-90), ultrasonic cleaning, rinsing4. length, frequency, iris and equator diameter measurement, select
half cells for dumbbells5. 20 μm chemical polishing of half cells (inner and outer surface),
ultrasonic cleaning, rinsing, storage6. 3 μm chemical polishing at iris area, rinsing
• Dumbbells fabrication (2009.6-11)7. welding of iris (two sides)8. insert stiffening rings with the dumbbell reshaping fixture9. welding of stiffening rings10. length and frequency measurement11. reshaping12. equator trimming
Dec.2, 2009 Jiyuan Zhai, 2nd Workshop of the IHEP 1.3 GHz SRF R&D Project 8
Fabrication Procedure (cont.)
13. degreasing, ultrasonic cleaning, rinsing
14. length, frequency, equator diameter measurement, select dumbbells for cavity welding
15. degreasing, ultrasonic cleaning, rinsing
16. 20 μm chemical polishing of dumbbells with the CP facility
17. inspection of inner surfaces for defects
18. grinding of defects (including heavey removal at iris area )
19. degreasing, ultrasonic cleaning, rinsing
20. 20 μm chemical polishing of dumbbells
21. ultrasonic cleaning, rinsing
22. 3 μm chemical polishing at equator region, storage with argon gas
We are here
Dec.2, 2009 Jiyuan Zhai, 2nd Workshop of the IHEP 1.3 GHz SRF R&D Project 9
Fabrication Procedure (cont.)• End groups fabrication (2009.8-12)
23. fabrication of seamless Nb beam tubes and evacuation short tube, NbTi flanges, NbTi end plates, Nb stiffening rings
24. pull out of the beam tube for the evacuation (input coupler) port
25. tubes trimming and polishing
26. degreasing, ultrasonic cleaning, rinsing
27. 20 μm chemical polishing
28. ultrasonic cleaning, rinsing
29. welding of end groups (insert stiffening rings with the end group reshaping fixture)
30. reshaping
31. equator trimming
32. degreasing, ultrasonic cleaning, rinsing
33. length, frequency, equator diameter measurement
We are here
Dec.2, 2009 Jiyuan Zhai, 2nd Workshop of the IHEP 1.3 GHz SRF R&D Project 10
Fabrication Procedure (cont.)34. degreasing, ultrasonic cleaning, rinsing
35. 20 μm chemical polishing of the end cell
36. inspection of inner surfaces for defects
37. grinding of defects
38. 20 μm chemical polishing of the end cell
39. ultrasonic cleaning, rinsing
40. 3 μm chemical polishing at equator, storage with argon gas
• Cavity Welding (2009.12)41. dumbbells welding (2-4-8)
42. end groups welding to dumbbell weldment
43. equator welding inspection
44. cavity vacuum, dimension and frequency check
Dec.2, 2009 Jiyuan Zhai, 2nd Workshop of the IHEP 1.3 GHz SRF R&D Project 11
The fabrication procedure refers to:
• D. Proch, DESY SPECIFICATION OF WELDED 1.3 GHz SUPERCONDUCTING RESONATORS FOR TTF/VUV-FEL, MHF-SL 09-2005
• M. Foley, D. Mitchell, T. Khabiboulline. FNAL Fabrication Specification for 3.9 GHz 3rd Harmonic Superconducting RF Cavities, ES-426451, 2008
• K. Saito and E. Kako of KEK, private communication, 2009
~1.5 mm
Dec.2, 2009 Jiyuan Zhai, 2nd Workshop of the IHEP 1.3 GHz SRF R&D Project 12
Spring back
Dec.2, 2009 Jiyuan Zhai, 2nd Workshop of the IHEP 1.3 GHz SRF R&D Project 13
Q~5000!kHz stable
Perturbation
13 Tuned Dumbbells & 4 End Groups
Dec.2, 2009 Jiyuan Zhai, 2nd Workshop of the IHEP 1.3 GHz SRF R&D Project 14
Dumbbell Grinding
CRATEXrubberized SiC
#7-14 after CP #12-13
Dec.2, 2009 Jiyuan Zhai, 2nd Workshop of the IHEP 1.3 GHz SRF R&D Project 15
Dumbbell CP and Transportation
Dec.2, 2009 Jiyuan Zhai, 2nd Workshop of the IHEP 1.3 GHz SRF R&D Project 16
Over flow Tank
Recirculation Pump
Main Acid Valve
AcidTank
Main Acid Pump
AcidSupply Tank
Acid Dump Tank
Acid Dump Valve
Acid Waste Barrel
Acid Dump Pump
Waste Gas Treatment
Dilute WasteBarrel
UPWTank
UPWPump
Ultra Pure Water (UPW)Barrel
UPWValve
Dilute Waste Valve
Fill in with Argon gas
EBW
Rinse in Class 10 Clean Room and Dry
Fixtures (by HJL)
1. inner half cell deep drawing dies
2. inner half cell trimming fixture
3. inner half cell reshaping fixture
4. end half cell deep drawing dies
5. end half cell trimming fixture
6. end half cell reshaping fixture
7. stiffening ring fabrication fixture
8. dumbbell trimming fixture
9. dumbbell reshaping fixture
10. end group reshaping fixture
11. end group trimming fixture
Dec.2, 2009 Jiyuan Zhai, 2nd Workshop of the IHEP 1.3 GHz SRF R&D Project 17
Fixtures and Jigs12. iris outer welding fixture
13. iris inner welding fixture
14. stiffening ring welding fixture
15. end group welding fixtures
16. cavity welding fixture
17. stainless steel jig for cavity CBP and CP
18. cavity rotating cart
19. cavity CBP cleaning fixture
20. frequency measurement fixtures
21. dumbbell CP fixture
22. dumbbell and end group storage fixtures
23. dumbbell and end group clean storage tanks
24. Ti jig for cavity HPR and vertical test
25. ……
Dec.2, 2009 Jiyuan Zhai, 2nd Workshop of the IHEP 1.3 GHz SRF R&D Project 18
for EBW, by BIAM
for CBP, by HJL
for RF measurement, CP, clean storage & transportation …, by other companies
Cavity Frequency Control
Dec.2, 2009 Jiyuan Zhai, 2nd Workshop of the IHEP 1.3 GHz SRF R&D Project 19
f / MHz
L / mm
1299.500
1300.000
1297.350
1
102
3
4
5
6
EP or CP
Pressure
Permittivity
Temperature
LHe Pressure
Cryomodule Vacuum
Pretuning Target
Cavity in Cryomodule
Iris Shrinkage& Deformation
DumbbellTrimming
Equator Shrinkage
Pretuning
Pretuning LengthTolerance Range Half cell Length
HALF CELLS9-CELL CAVITY
7
8
9
Stiffening Ring Shrinkage
DumbbellDeform and Reform
Annealing
EP or CP
CBP
15
11
12
13
14
DUMBBELLS
Dumbbell Reform Length Target
Dumbbell LengthTarget
Measurable Frequency Point
Unmeasurable Frequecy Point
Controllable Frequecy Change
Uncontrollable Frequency Change
Tuning Available Region
EP or CP limit
Horizontal Test Tuner Tuning Range, typically Slow tuner 500 kHz, Piezo 1 kHz
Cavity Length Range(~ 2 mm)
Field Flatness Tuning
Cavity Vertical Test
VT Power Source Range
0 Tuner Preload (HT)
5 to 2
0
-1
-2
-1
13
Key Frequency Point
Final Frequency Target
Cavity Frequency Change and Control
achieve simultaneously the correct length and the correct frequency of the 9-cell cavity
achieve simultaneously the correct length and the correct frequency of the 9-cell cavity
Cavity BW: ~300 HzTuner range: 500 kHzCavity BW: ~300 HzTuner range: 500 kHz
+ 350 kHz /mm
- 180 kHz /mm
Cavity Frequency Evolution频变因素
Frequency Changing Items频变 Δf
/ kHz中心频率 f
/ kHz频率上限
fmax频率下限
fmin
半腔改变half cell ΔL
/ mm
半腔长half cell L
/mm
长度上限Lmax
长度下限Lmin
备注Notes
参数Related Parameters
半腔(根据 9-cell腔统计计算) 1,300,000 1,300,530 1,299,470 57.69 58.04 57.34 水平测试频率( HT target ) 室温 / 摄氏度 23
焊接及预载拉伸( HV welding & Tuner preload ) 500 1,300,000 1,300,530 1,299,470 0.08 57.69 58.04 57.34 均为施加此行影响因素后的频率 湿度 / % 40
低温槽抽真空( Cryomudule evacuation ) 100 1,299,500 1,300,030 1,298,970 0.00 57.61 57.96 57.26 大气压 / hPa 101.325
液氦压力变化( He Pressure Decrease ) 150 1,299,400 1,299,930 1,298,870 -0.02 57.61 57.96 57.26 4.2K-2K 液氦压力变化?垂直测试频率 9-cell 腔频率 - 长度系数 kHz/mm 350
液氦温度变化( Temperature Decrease ) 1885 1,299,250 1,299,780 1,298,720 -0.05 57.63 57.98 57.28 室温至 4.2K (公式计算) 半腔频率 - 长度系数 kHz/mm 6300
腔抽真空( Cavity evacuation ) 415 1,297,365 1,297,895 1,296,834 -0.02 57.68 58.03 57.33 介电常数和压力变化(温度湿度相关) 半腔 Pi 模频率 - 赤道直线系数 kHz/mm -3170
其他因素( other items ) 0 1,296,949 1,297,480 1,296,419 0.00 57.70 58.05 57.35 水平测试前腔自由频率(大气) 半腔 0 模频率 - 赤道直线系数 kHz/mm -2657
垂直测试洛伦兹失谐( VT LD) -44 1,296,949 1,297,480 1,296,419 0.00 57.70 58.05 57.35 半腔 Pi 模频率 - 束孔直线系数 kHz/mm -1700
垂直测试输入探针( VT attenna ) -18 1,296,993 1,297,524 1,296,463 0.00 57.70 58.05 57.35 半腔 0 模频率 - 束孔直线系数 kHz/mm 1324
第二次 CP 或 EP ( Second CP or EP ) -400 1,297,011 1,297,542 1,296,481 0.00 57.70 58.05 57.35 垂直测试前腔自由频率(大气) CP,EP,CBP 厚度 - 频率系数 kHz / μm -10
预调谐( Pretuning ) 0 1,297,411 1,297,942 1,296,881 0.00 57.70 58.05 57.35 预调谐目标 垂直测试洛伦兹失谐系数 Hz / (MV/m) 2 -2
退火( Anealing / outgasing) 100 1,297,411 1,297,942 1,296,881 -0.06 57.70 58.05 57.35 超导腔梯度 / MV/m 35
第一次 CP 或 EP ( Second CP or EP ) -800 1,297,311 1,297,842 1,296,781 0.00 57.76 58.11 57.41 水平测试洛伦兹失谐系数 Hz / (MV/m) 2 1
滚磨抛光( CBP) -800 1,298,111 1,298,642 1,297,581 0.00 57.76 58.11 57.41 第二次 CP 或 EP 量 / μm 40
赤道焊接( Equator welding) 634 1,298,911 1,299,442 1,298,381 -0.20 57.76 58.11 57.41 第一次 CP 或 EP 量 / μm 80
赤道切削( Equator trimming) 0 1,298,277 1,298,808 1,297,747 0.00 57.96 58.31 57.61 滚磨抛光量 / μm 80
束孔焊接( Iris welding) 340 1,298,277 1,298,808 1,297,747 -0.20 57.96 58.31 57.61 哑铃赤道切削量计算用频率目标 赤道单边焊接收缩量 / mm -0.2
赤道微波余量 -3170 1,297,937 1,298,468 1,297,407 1.00 58.16 58.51 57.81 哑铃(半腔)切削 赤道微波余量 1
赤道焊接余量 -634 1,301,107 1,301,638 1,300,577 0.20 57.16 57.51 56.81 赤道焊接余量 0.2
束孔焊接余量 -340 1,301,741 1,302,272 1,301,211 0.20 56.96 57.31 56.61 束孔焊接余量 0.2
原始半腔设计值( half cell ) 1,302,081 1,302,612 1,301,551 56.76 57.11 56.41 束孔单边焊接收缩量 / mm -0.2
原始半腔 0模设计值( half cell 0 mode) 1,282,081 56.76 赤道切削量 0
赤道微波余量0 模 -2657 1,279,424 半腔调谐量 0
赤道焊接余量0 模 -531 1,278,893 9-cell 长度单边误差 1.5
束孔焊接余量0 模 265 1,279,158 58.16 58.51 57.81 哑铃(半腔) 0 模切削、预调谐目标(参考) 半腔长度单边误差 0.35
Dec.2, 2009 Jiyuan Zhai, 2nd Workshop of the IHEP 1.3 GHz SRF R&D Project 20
Half Cells Data
Dec.2, 2009 Jiyuan Zhai, 2nd Workshop of the IHEP 1.3 GHz SRF R&D Project 21
Earrings and steps were found in the equator area.
Large cracks and unsmoothness were found between adjacent grains in the iris area.
Iris wall thickness was not uniform after trimming.
Dumbbell Reshaping and Tuning
Dec.2, 2009 Jiyuan Zhai, 2nd Workshop of the IHEP 1.3 GHz SRF R&D Project 22
The shrinkage of the dumbbell length after iris two sides EBW and stiffening ring EBW is about 2 mm. Need reshaping.
Perturbation method to measure the frequency of the individual half cells of a dumbbell.
Trim to tune the half cells individually.
SRF09 paper: DUMBBELL FABRICATION AND TUNING OF THE IHEP LARGE GRAIN 9-CELL CAVITY
Dumbbell Matching
23
Freq. before EBW
Length before EBW
Inner Dia. of Equator
Freq. after EBW
Trimming Length
Estimated Freq. after trimming
Freq. after Trimming
Pretuning LengthAverage Freq.
of cells
#18 1279.563 59.00 196.32 1298.968 0.35 1300.090 1299.086 0.29 1301.777
#29 1278.763 59.72 196.37 1300.043 0.72 1302.320 1304.468 0.64 #08 1281.722 59.90 196.38 1301.701 0.64 1303.730 1305.144 0.87
1301.778 #19 1278.512 58.66 196.43 1298.154 0.22 1298.840 1298.411 0.09 #51 1275.288 59.49 196.43 1294.822 1.12 1298.380 1298.089 0.02
1301.704 #10 1281.501 58.29 196.45 1304.393 -0.05 1302.160 1305.318 0.62 #48 1276.070 59.34 196.45 1296.750 0.79 1299.250 1298.878 0.16
1299.611 #21 1278.994 60.60 196.46 1299.352 0.57 1301.140 1300.344 0.45 #11 1277.938 59.12 196.47 1299.420 0.38 1300.640 1298.079 0.38
1298.843 #50 1275.892 59.41 196.47 1297.320 0.81 1299.880 1299.607 0.25 #30 1277.715 59.51 196.50 1297.830 0.82 1300.430 1299.229 0.34
1300.290 #09 1278.667 59.42 196.51 1298.928 0.61 1300.870 1301.351 0.41 #20 1278.981 58.96 196.51 1299.574 0.27 1300.420 1300.256 0.34
1302.505 #25 1275.623 59.38 196.51 1296.165 0.91 1299.050 1304.754 0.12 #24 1276.386 59.39 196.54 1296.012 0.90 1298.870 1298.924 0.09
1298.198 #23 1275.428 59.45 196.58 1295.048 1.07 1298.340 1297.472 0.01 #27 1277.149 59.67 196.58 1297.649 0.95 1300.650 1303.034 0.38
1300.403 #28 1274.419 59.20 196.60 1296.759 0.71 1299.000 1297.772 0.11 #31 1277.553 59.55 196.64 1298.126 0.83 1300.750 1299.591 0.39
1299.217 #49 1274.927 59.48 196.64 1296.383 0.95 1299.380 1298.843 0.17 #53 1273.979 59.26 196.64 1297.667 0.67 1299.790 1299.003 0.24
1299.194 #52 1275.285 59.45 196.87 1296.734 0.86 1299.460 1299.384 0.19
Average Freq.( 8 dumbbells) 1299.682
After EBW 1300.316
After Surface Treatment 1298.816
Average Tuning Length 0.45
Pretuning Target 1297.411
Average Length 116.32
Total Cell Length 1042.53
After EBW 1038.93
Design Length 1035.04
Difference 3.89
Average Tuning Length
0.49
Match to make the field flatness flat or,
Tilt the fundamental mode field to let the trapped mode out.
Similar equator inner diameter may be the most important criteria.
We can tune the cavity to the correct frequency and length at the same time.
Cavity EBW
11.16 11.23 11.30 12.7 12.14 12.28
1 End Group EBW
2 Flange trimming
3 CP commissioning
4 Dumbbell Grinding
5 Dumbbell CP
6 Dumbbell EBW
7 End Group Reshaping
8 End Group Trimming
9 End Group CP
10 Cavity EBW
Dec.2, 2009 Jiyuan Zhai, 2nd Workshop of the IHEP 1.3 GHz SRF R&D Project 24
Outline
• Cavity R&D Goals and the Overall Schedule
• 9-cell Cavity with Bare Tubes (IHEP-01)– Fabrication and Tuning Procedure
– Surface Treatment and Vertical Test Plan
• 9-cell Cavity with Full End Groups (IHEP-02)– Design & Fabrication Consideration and Progress
Dec.2, 2009 Jiyuan Zhai, 2nd Workshop of the IHEP 1.3 GHz SRF R&D Project 25
IHEP-01 Surface Treatment and Vertical Test Schedule
Year 2010
Month 1 2 3 4 5 6
Week 1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4
CBP
CP
Annealing
Pretuning
2nd CP
Assemble and Packing
Shipping to KEK
HPR in KEK
1st VT in KEK (early case)
Inspection in KEK
CP in KEK or back to IHEP
Second treatment loop (EP?)
2nd VT test?
1st VT in KEK (late case)
Beijing GDEChinese New Year
Kyoto IPAC
Golden Week
Dec.2, 2009 Jiyuan Zhai, 2nd Workshop of the IHEP 1.3 GHz SRF R&D Project 26
CBP, CP and Pretuning• 9-cell cavity CBP machine initial commissioning done
• CP and Pretuning facility in commissioning (Dai Jianping’s talk)
Dec.2, 2009 Jiyuan Zhai, 2nd Workshop of the IHEP 1.3 GHz SRF R&D Project 27
Over flow Tank
Recirculation Pump
Main Acid Valve
AcidTank
Main Acid Pump
AcidSupply Tank
Acid Dump Tank
Acid Dump Valve
Acid Waste Barrel
Acid Dump Pump
Waste Gas Treatment
Dilute WasteBarrel
UPWTank
UPWPump
Ultra Pure Water (UPW)Barrel
UPWValve
Dilute Waste Valve
Cool water spray
Inner Surface Inspection
• IHEP Gastroscope Camera not suitable• GE Industrial Inspection: distance, depth (10 μm resolution) • Need to improve the light source
Dec.2, 2009 Jiyuan Zhai, 2nd Workshop of the IHEP 1.3 GHz SRF R&D Project 28
equator equator
Kyoto Camera
• Developed by Kyoto University and KEK (Hayano-san)– Iwashita-san of Kyoto University visited IHEP in Oct.25– Fermilab bought one; more labs will use
• Very Important and Useful Tool (Watanabe-san’s talk)– Inspect after EBW, after CP or EP, after Vertical Test– Coincide with the T-mapping and passband measurement– Repair the inner surface and increase or recover the cavity performance
• Can we borrow STF’s old Kyoto camera?
Dec.2, 2009 Jiyuan Zhai, 2nd Workshop of the IHEP 1.3 GHz SRF R&D Project 29
Vertical Test
• Vertical test in KEK– Every interface the same with KEK STF– Use STF’s input coupler, pick up antenna,
etc.• T-mapping (Yamamoto-san’s talk)
– important and complex system, use STF’s T-mapping
– No problem with the fish bone fixture– Need to check the X-ray detector
mounting• Inner surface inspection
– Kyoto Camera in STF is OK for the IHEP cavity (60 mm iris)
Dec.2, 2009 Jiyuan Zhai, 2nd Workshop of the IHEP 1.3 GHz SRF R&D Project 30
Outline
• Cavity R&D Goals and the Overall Schedule
• 9-cell Cavity with Bare Tubes (IHEP-01)– Fabrication and Tuning Procedure
– Surface Treatment and Vertical Test Plan
• 9-cell Cavity with Full End Groups (IHEP-02)– Design & Fabrication Consideration and Progress
Dec.2, 2009 Jiyuan Zhai, 2nd Workshop of the IHEP 1.3 GHz SRF R&D Project 31
Physics Requirement
• XFEL, low current ERL and the ILC beam physics requirement
for the cavity is similar
– Qext < 105 for the high R/Q modes
– “F” shape HOM coupler can handle up to ~ 5 W power. For ILC:
• High Current ERL needs much stronger HOM damping
– RF absorber in the beam pipe (as BEPCII)
Dec.2, 2009 Jiyuan Zhai, 2nd Workshop of the IHEP 1.3 GHz SRF R&D Project 32
2 19 10 2( ) 15V / pc (1.6 10 C 2 10 ) 2625 5Hz 2WHOM l b b revP k eN n f
ERL HOM Power: 77 pC, 100 mA, 0.6 mm, 200 W (up to 100GHz), Qext < 103
BEPCII: kl =0.44V / pC, 2 2( ) / 3.11kWHOM l b b rev l b b revP k eN n f k I n f
Design and Fabrication Consideration
• Keep the same inner cell shape• Improve the fabrication and surface treatment technique!!
– Improve deep drawing of the large grain Nb; recheck Nb disks– Trimming thinner equator, optimize EBW parameters (defects) and vacuum (RRR)– Simplify dumbbell tuning– ……..
• Identify dangerous modes up to 3 GHz– TE111(hybrid), TM011, TM110, TM111 (high R/Q)
– TE121 (small R/Q, but trap)
• Optimize the end cell to let the trapped mode out– TM111 and TE121
• HOM coupler RF bench test– Make the HOM coupler copper model
test with the coaxial line and 9-cell copper cavity– Measure the HOM properties of
the STF baseline 9-cell cavity (deliver next week)
Dec.2, 2009 Jiyuan Zhai, 2nd Workshop of the IHEP 1.3 GHz SRF R&D Project 33
RF Design Progress (Zhao Tongxian)
Dipole R/Q of the TESLA cavity
Similar HOM freq and R/Q with DESY Wanzenberg’s Mafia 2D results (within 10% difference for large R/Q modes)
Dec.2, 2009 Jiyuan Zhai, 2nd Workshop of the IHEP 1.3 GHz SRF R&D Project 34
Monopole and dipole R/Q of the IHEP cavity
R/Q higher than TESLANeed more meshes to get better accuracyIdentify more trapped modes
Qext Simulation Methods
• Use several methods to cross-check the results1. Eigen mode method (CST): integrate over the pick up port
• directly give the external Q (Microwave Studio)
2. Time domain method (CST): time consuming
3. Frequency domain method (CST or HFSS):• Transmission method (extra excitation)
• Reflection method (self excitation, simple calculation)
– impedance method
– VSWR method
Dec.2, 2009 Jiyuan Zhai, 2nd Workshop of the IHEP 1.3 GHz SRF R&D Project 35
0
2 1ext
fQ
f f
2 41 2 1 4
2ext
0
0
over coupled
1 under coupled
0
ext
ext
fQ
f
Preliminary Qext Results with theTESLA HOM coupler and cavity (Zhao Tongxian)
Dec.2, 2009 Jiyuan Zhai, 2nd Workshop of the IHEP 1.3 GHz SRF R&D Project 36
103 10extQ
410extQ
TM010 Pi
TE111 7 Pi / 9
Next step: frequency sensitivity, optimize the loop and angle for the low loss shape cavity
1.293368 | 1.03e+010 TM0101.625063 | 8.17e+004 TE1111.625318 | 3.56e+005 TE1111.801103 | 1.22e+003 TM1101.804886 | 2.48e+004 TM110
Passband simulation
End cell simulation
9 for Pi modeextQ (GHz)f
9-cell cavity simulation
Need more meshes and cross-check
Other Considerations• Lorentz Force Detuning Simulation (Xiao Rongchuan)
– Optimize the stiffening ring position
– Strengthen the end plate structure (Men Lingling)
• End Group Design– Total length: 1247 mm too tight for low loss shape with HOM coupler!
– Input coupler position & Qext (44 mm? 54 mm? More?)
– HOM coupler position & Qext
• Helium vessel– Smallest diameter?
– Nb-NbTi-Ti, welding technique
• Magnetic shield– Inside or outside?
• Flange interfaces– Keep the compatibility with KEK STF
– Input coupler: KEK STF type (60 mm diameter)
– Tuner: STF type, in the middleDec.2, 2009 Jiyuan Zhai, 2nd Workshop of the IHEP 1.3 GHz SRF R&D Project 37
Fabrication TechniqueFabrication Technique
Physics RequirementPhysics Requirement
Plug CompatibilityPlug Compatibility
?
Summary
• The multi-cell cavity is one of the key components for 1.3 GHz SRF technology R&D of IHEP.
• We have developed effective methods, procedures, tools and facilities to fabricate and tune the 9-cell cavity.
• The first 9-cell cavity will finish fabrication and EBW in 2009, surface treated at IHEP and test at KEK STF in early 2010.
• We expect fruitful achievement in collaboration with KEK.
Dec.2, 2009 Jiyuan Zhai, 2nd Workshop of the IHEP 1.3 GHz SRF R&D Project 38
For the Dream Machine
Thank you!