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 2 nd Workshop of the IHEP 1.3 GHz SRF R&D Project & 2 nd 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, 2009Jiyuan Zhai, 2nd Workshop of the IHEP 1.3 GHz SRF R&D Project2

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 – MV / m for the vertical test – MV / m for the horizontal test –Q 0, HOM damping, Lorentz force detuning Dec.2, 2009Jiyuan Zhai, 2nd Workshop of the IHEP 1.3 GHz SRF R&D Project3

9-cell Cavity Overall Schedule CavityDuration IHEP fabrication st test loop nd test loop IHEP fabrication st test loop nd test loop weld helium vessel assemble and HT ? Dec.2, 2009Jiyuan Zhai, 2nd Workshop of the IHEP 1.3 GHz SRF R&D Project4 20 MV/m 25 MV/m S0 25 MV/m S0 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, 2009Jiyuan Zhai, 2nd Workshop of the IHEP 1.3 GHz SRF R&D Project5

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, 2009Jiyuan Zhai, 2nd Workshop of the IHEP 1.3 GHz SRF R&D Project6

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, 2009Jiyuan Zhai, 2nd Workshop of the IHEP 1.3 GHz SRF R&D Project7

Fabrication Procedure Half cells fabrication ( ) 1.deep drawing, iris coining, trimming (L= L nom +ΔL iris +ΔL equ +ΔL tuning ) 2.CMM dimension check, equator roundness reshaping 3.degreasing(micro-90), ultrasonic cleaning, rinsing 4.length, frequency, iris and equator diameter measurement, select half cells for dumbbells 5.20 μm chemical polishing of half cells (inner and outer surface), ultrasonic cleaning, rinsing, storage 6.3 μm chemical polishing at iris area, rinsing Dumbbells fabrication ( ) 7.welding of iris (two sides) 8.insert stiffening rings with the dumbbell reshaping fixture 9.welding of stiffening rings 10.length and frequency measurement 11.reshaping 12.equator trimming Dec.2, 2009Jiyuan Zhai, 2nd Workshop of the IHEP 1.3 GHz SRF R&D Project8

Fabrication Procedure (cont.) 13.degreasing, ultrasonic cleaning, rinsing 14.length, frequency, equator diameter measurement, select dumbbells for cavity welding 15.degreasing, ultrasonic cleaning, rinsing 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 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, 2009Jiyuan Zhai, 2nd Workshop of the IHEP 1.3 GHz SRF R&D Project9

Fabrication Procedure (cont.) End groups fabrication ( ) 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 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, 2009Jiyuan Zhai, 2nd Workshop of the IHEP 1.3 GHz SRF R&D Project10

Fabrication Procedure (cont.) 34.degreasing, ultrasonic cleaning, rinsing μm chemical polishing of the end cell 36.inspection of inner surfaces for defects 37.grinding of defects μm chemical polishing of the end cell 39.ultrasonic cleaning, rinsing 40.3 μm chemical polishing at equator, storage with argon gas Cavity Welding ( ) 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, 2009Jiyuan Zhai, 2nd Workshop of the IHEP 1.3 GHz SRF R&D Project11 The fabrication procedure refers to: D. Proch, DESY SPECIFICATION OF WELDED 1.3 GHz SUPERCONDUCTING RESONATORS FOR TTF/VUV-FEL, MHF-SL M. Foley, D. Mitchell, T. Khabiboulline. FNAL Fabrication Specification for 3.9 GHz 3rd Harmonic Superconducting RF Cavities, ES , 2008 K. Saito and E. Kako of KEK, private communication, 2009

~1.5 mm Dec.2, 2009Jiyuan Zhai, 2nd Workshop of the IHEP 1.3 GHz SRF R&D Project12 Spring back

Dec.2, 2009Jiyuan Zhai, 2nd Workshop of the IHEP 1.3 GHz SRF R&D Project13 Q~5000! kHz stable Perturbation

13 Tuned Dumbbells & 4 End Groups Dec.2, 2009Jiyuan Zhai, 2nd Workshop of the IHEP 1.3 GHz SRF R&D Project14

Dumbbell Grinding CRATEX rubberized SiC #7-14 after CP#12-13 Dec.2, 2009Jiyuan Zhai, 2nd Workshop of the IHEP 1.3 GHz SRF R&D Project15

Dumbbell CP and Transportation Dec.2, 2009Jiyuan Zhai, 2nd Workshop of the IHEP 1.3 GHz SRF R&D Project16 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, 2009Jiyuan Zhai, 2nd Workshop of the IHEP 1.3 GHz SRF R&D Project17

Fixtures and Jigs 12.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, 2009Jiyuan Zhai, 2nd Workshop of the IHEP 1.3 GHz SRF R&D Project18 for EBW, by BIAM for CBP, by HJL for RF measurement, CP, clean storage & transportation …, by other companies

Cavity Frequency Control Dec.2, 2009Jiyuan Zhai, 2nd Workshop of the IHEP 1.3 GHz SRF R&D Project19 achieve simultaneously the correct length and the correct frequency of the 9-cell cavity Cavity BW: ~300 Hz Tuner range: 500 kHz Cavity BW: ~300 Hz Tuner range: 500 kHz kHz /mm 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） 1,300,0001,300,5301,299, 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 ） 5001,300,0001,300,5301,299, 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 ） 1001,299,5001,300,0301,298, 大气压 / hPa 液氦压力变化（ He Pressure Decrease ） 1501,299,4001,299,9301,298, K-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 ） 18851,299,2501,299,7801,298, 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 ） 4151,297,3651,297,8951,296, 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 其他因素（ other items ） 01,296,9491,297,4801,296, 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 垂直测试洛伦兹失谐（ VT LD ） -441,296,9491,297,4801,296, 半腔 Pi 模频率 - 束孔直线系数 kHz/mm 垂直测试输入探针（ VT attenna ） -181,296,9931,297,5241,296, 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 ） -4001,297,0111,297,5421,296, 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 ） 01,297,4111,297,9421,296, 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) 1001,297,4111,297,9421,296, 超导腔梯度 / MV/m 35 第一次 CP 或 EP （ Second CP or EP ） -8001,297,3111,297,8421,296, 水平测试洛伦兹失谐系数 Hz / (MV/m) 2 1 滚磨抛光（ CBP ） -8001,298,1111,298,6421,297, 第二次 CP 或 EP 量 / μm 40 赤道焊接（ Equator welding) 6341,298,9111,299,4421,298, 第一次 CP 或 EP 量 / μm 80 赤道切削（ Equator trimming) 01,298,2771,298,8081,297, 滚磨抛光量 / μm 80 束孔焊接（ Iris welding) 3401,298,2771,298,8081,297, 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 ,297,9371,298,4681,297, 哑铃（半腔）切削赤道微波余量 1 赤道焊接余量 -6341,301,1071,301,6381,300, 赤道焊接余量 0.2 束孔焊接余量 -3401,301,7411,302,2721,301, 束孔焊接余量 0.2 原始半腔设计值（ half cell ） 1,302,0811,302,6121,301, 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, 赤道切削量 0 赤道微波余量 0 模 ,279,424 半腔调谐量 0 赤道焊接余量 0 模 -5311,278,893 9-cell 长度单边误差 1.5 束孔焊接余量 0 模 2651,279, 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, 2009Jiyuan Zhai, 2nd Workshop of the IHEP 1.3 GHz SRF R&D Project20

Half Cells Data Dec.2, 2009Jiyuan Zhai, 2nd Workshop of the IHEP 1.3 GHz SRF R&D Project21 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, 2009Jiyuan Zhai, 2nd Workshop of the IHEP 1.3 GHz SRF R&D Project22 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 Trimmin g Length Estimated Freq. after trimming Freq. after Trimming Pretuning Length Average Freq. of cells # # # # # # # # # # # # # # # # # # # # # # Average Freq. ( 8 dumbbells) After EBW After Surface Treatment Average Tuning Length 0.45 Pretuning Target Average Length Total Cell Length After EBW Design Length Difference3.89 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 End Group EBW 2Flange trimming 3CP commissioning 4Dumbbell Grinding 5Dumbbell CP 6Dumbbell EBW 7End Group Reshaping 8End Group Trimming 9End Group CP 10Cavity EBW Dec.2, 2009Jiyuan Zhai, 2nd Workshop of the IHEP 1.3 GHz SRF R&D Project24

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, 2009Jiyuan Zhai, 2nd Workshop of the IHEP 1.3 GHz SRF R&D Project25

IHEP-01 Surface Treatment and Vertical Test Schedule Year2010 Month Week CBP CP Annealing Pretuning 2 nd CP Assemble and Packing Shipping to KEK HPR in KEK 1 st VT in KEK (early case) Inspection in KEK CP in KEK or back to IHEP Second treatment loop (EP?) 2 nd VT test? 1 st VT in KEK (late case) Beijing GDEChinese New Year Kyoto IPAC Golden Week Dec.2, 2009Jiyuan Zhai, 2nd Workshop of the IHEP 1.3 GHz SRF R&D Project26

CBP, CP and Pretuning 9-cell cavity CBP machine initial commissioning done CP and Pretuning facility in commissioning (Dai Jianping’s talk) Dec.2, 2009Jiyuan Zhai, 2nd Workshop of the IHEP 1.3 GHz SRF R&D Project27

Inner Surface Inspection IHEP Gastroscope Camera not suitable GE Industrial Inspection: distance, depth (10 μm resolution) Need to improve the light source Dec.2, 2009Jiyuan Zhai, 2nd Workshop of the IHEP 1.3 GHz SRF R&D Project28 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, 2009Jiyuan Zhai, 2nd Workshop of the IHEP 1.3 GHz SRF R&D Project29

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, 2009Jiyuan Zhai, 2nd Workshop of the IHEP 1.3 GHz SRF R&D Project30

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, 2009Jiyuan Zhai, 2nd Workshop of the IHEP 1.3 GHz SRF R&D Project31

Physics Requirement XFEL, low current ERL and the ILC beam physics requirement for the cavity is similar –Q ext < 10 5 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, 2009Jiyuan Zhai, 2nd Workshop of the IHEP 1.3 GHz SRF R&D Project32 ERL HOM Power: 77 pC, 100 mA, 0.6 mm, 200 W (up to 100GHz), Q ext < 10 3 BEPCII: k l =0.44V / pC,

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, 2009Jiyuan Zhai, 2nd Workshop of the IHEP 1.3 GHz SRF R&D Project33

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, 2009Jiyuan Zhai, 2nd Workshop of the IHEP 1.3 GHz SRF R&D Project34 Monopole and dipole R/Q of the IHEP cavity R/Q higher than TESLA Need more meshes to get better accuracy Identify more trapped modes

Q ext Simulation Methods Use several methods to cross-check the results 1.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, 2009Jiyuan Zhai, 2nd Workshop of the IHEP 1.3 GHz SRF R&D Project35

Preliminary Q ext Results with the TESLA HOM coupler and cavity (Zhao Tongxian) Dec.2, 2009Jiyuan Zhai, 2nd Workshop of the IHEP 1.3 GHz SRF R&D Project36 TM010 Pi TE111 7 Pi / 9 Next step: frequency sensitivity, optimize the loop and angle for the low loss shape cavity | 1.03e+010 TM | 8.17e+004 TE | 3.56e+005 TE | 1.22e+003 TM | 2.48e+004 TM110 Passband simulation End cell simulation 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 & Q ext (44 mm? 54 mm? More?) –HOM coupler position & Q ext 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 middle Dec.2, 2009Jiyuan Zhai, 2nd Workshop of the IHEP 1.3 GHz SRF R&D Project37 Fabrication Technique Physics Requirement Plug 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 We expect fruitful achievement in collaboration with KEK. Dec.2, 2009Jiyuan Zhai, 2nd Workshop of the IHEP 1.3 GHz SRF R&D Project38

For the Dream Machine Thank you!