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


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?


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


• 9-cell Cavity with Bare Tubes (IHEP-01)– Fabrication and Tuning Procedure


• 9-cell Cavity with Full End Groups (IHEP-02)– Design & Fabrication Consideration and Progress


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


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)


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


Fabrication Procedure (cont.)

13. degreasing, ultrasonic cleaning, rinsing

14. length, frequency, equator diameter measurement, select dumbbells for cavity welding


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 )


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


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


27. 20 μm chemical polishing


29. welding of end groups (insert stiffening rings with the end group reshaping fixture)

30. reshaping

31. equator trimming


33. length, frequency, equator diameter measurement

We are here


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


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


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


Spring back


Q~5000!kHz stable

Perturbation

13 Tuned Dumbbells & 4 End Groups


Dumbbell Grinding

CRATEXrubberized SiC

#7-14 after CP #12-13


Dumbbell CP and Transportation


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


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. ……


for EBW, by BIAM

for CBP, by HJL

for RF measurement, CP, clean storage & transportation …, by other companies

Cavity Frequency Control


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


Half Cells Data


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


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


Outline






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


CBP, CP and Pretuning• 9-cell cavity CBP machine initial commissioning done

• CP and Pretuning facility in commissioning (Dai Jianping’s talk)


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


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?


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)


Outline






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)


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)


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)


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


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)


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.


For the Dream Machine

Thank you!

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IHEP 1.3 GHz 9-cell Cavity R&D Status and Plan

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