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9-cell Cavity R&D Progress and Test Plan

9-cell Cavity R&D Progress and Test Plan. GAO Jie ( 高杰 ) ZHAI Jiyuan ( 翟纪元 ) YU Jing ( 玉静 ) LI Zhongquan ( 李中泉 ) ZHAO Tongxian ( 赵同宪 ) GU Jun ( 谷俊 ) HOU Mi ( 侯汨 ) SUN Yaolin ( 孙耀霖 ) ZHAO Facheng ( 赵发成 ) ZHANG Jingru ( 张敬如 ) Institute of High Energy Physics

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9-cell Cavity R&D Progress and Test Plan

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  1. 9-cell Cavity R&D Progress and Test Plan GAO Jie (高杰) ZHAI Jiyuan (翟纪元) YU Jing (玉静)LI Zhongquan(李中泉) ZHAO Tongxian (赵同宪) GU Jun (谷俊) HOU Mi (侯汨) SUN Yaolin (孙耀霖) ZHAO Facheng (赵发成) ZHANG Jingru (张敬如) Institute of High Energy Physics CHEN Jinzhe (陈晋哲) Beijing Hejieli Science and Technology Development Co. Ltd. YUAN Hong (袁鸿) Beijing Institute of Aviation Materials First Mini-Workshop on IHEP 1.3 GHz Superconducting RF Project June 10, 2009 IHEP, Beijing, China

  2. Outline • R&D plan & schedule • Cavity shape and material • Bare tube cavity fabrication progress • Surface preparation plan at IHEP • Vertical test issues at KEK STF • End cell and HOM coupler design

  3. R&D Plan and Goal • Bare tube 9-cell cavity IL9-0 (with pumping port) • Low loss shape, large grain niobium (Ningxia) • Fabricate and surface treat at IHEP, vertical test at KEK STF • 20 MV / m in the end of 2009 (Chemical polishing only) • 25-30 MV / m in 2010 after several test loops at IHEP • Electro-polishing in KEK STF as an alternative • Full end group 9-cell cavity • Low loss shape, large grain niobium (Ningxia) • Start fabrication in late 2009, test in the middle of 2010 • 25 MV / m in 2010 • Dress and horizontal test (25 MV / m) at IHEP in 2011 • Several more 9-cell cavities in 2010-2012…

  4. IL9-0 2009 Schedule • May 15 – July 30：Cavity EBW • First two dumbbells in this week • Aug. 1 – Sept. 30：Surface treatment in IHEP • Surface inspection, CBP, CP, Annealing, Pretuning, HPR • Oct. 20 – Dec. 20：Vertical test in KEK STF • more surface treatment and pretuning in STF

  5. Cavity Shape and Material • Inner cell: Low loss shape • modified from the original low loss type in 2005 • Single cell cavity achievement • 3 Ningxia large grain cavities, made by KEK, reached 47 MV/m by EP • 2 Ningxia large grain cavities, fabricated and treated in IHEP, tested in KEK in March 2008 , reached 40 MV/m by CBP+CP • 1 of the 4 fine grain cavities for reference study FG FG FG FG LG LG

  6. Large Grain Niobium • Advantages: • no Q-slope at high gradient with only CP, may eliminate EP • Directly slicing from ingot, may reduce the material contamination and cost (by multi-wire slicing) • Disadvantages: • Mainly in fabrication and EBW: earring after deep drawing, big grain steps, bad roundness and wall thickness uniformity…

  7. 9-cell cavity design Total Length: 1247 mm End cell design without HOM consideration No equator thickness trimming for EBW Next cavity will adopt equator trimming and biting structure 17 pages of drawings More detail discussions later

  8. End Group End plate and stiffening rings to strengthen the end cell Pumping port for evacuation before and during vertical test Pump the cavity at 2K, necessary? STF flanges and Helix gaskets

  9. Niobium Sheets Quality Assurance Properties: • Chemical composition • RRR ~ 430 • elongation, hardness • need more specifications and tests Defect Inspection: • Eddy current scan • Ultrasonic scan • got some initial results, under further investigation

  10. Fabrication Deep drawing and coining Half cell after drawing (earring due to large grain) Trimming Equator roundness reshaping Trimmed half cell Normal length + EBW shrinkage allowance + 1mm RF tuning allowance Degrease and ultrasonic clean with Miro-90, rinse

  11. 3D measurement, spring back and reshaping Dumbbell contour, height & parallel reshaping ~1.5 mm 180° 0° Trimming jig (locating error due to spring back) Dumbbell Reshaping jig (stiffening ring position unchanged) 270° 90° Half cell 12# CMM Equator Roundness 0.595mm Iris Roundness 0.388mm CMM on 4 test half cells

  12. Half cell dimension and frequency measurement

  13. New frequency measurement fixture The old plain and hard contact need much more press and good equator surface flatness This method is originated from Timergali of FNAL. Easy setting and accurate measurement Radial slots and elastic washer for good RF contact measurement with the old fixture: Freq. jump ~ 30 MHz, Q < 900 Antenna length optimized for small perturbation and noise Frequency stable in kHz Q ~ 4500

  14. Half cell height and frequency data

  15. Half cell CP and EBW • (Degreasing and ultrasonic cleaning) • CP 20 μm (40-60℃!) (away from silicon products, plastics like Teflon, fingerprint … !) • Rinse with UPW until 10 MΩ cm • Dry in class 10 clean room • Ultrasonic clean and 3 μm CP at iris, rinse • Put in container filled with argon gas • Send to BIAM for EBW (many details…) • Refer to DESY specification 2005

  16. Frequency estimation

  17. Frequency estimation (cont.)

  18. Dumbbell and cavity tuning （58.16±0.35 mm，1297.937±0.53 MHz） cellfrequency difference and filed flatness， 99.96%

  19. Dumbbell matching • Criterion • Similar iris average diameter and wall thickness • Exclude the pre-matched* cell-pair C’ij *Pre-matching: cell matching before dumbbell welding and measurement, supposing the length of the half cell does not change due to reshaping. • Make dumbbell pair: DBij (HCi-HCj) i is the marker numbers on the half cells • Will be done next week

  20. Cell matching • Criterion • Similar equator diameter and thickness • Smallest cell frequency deviation • Pretuning available range

  21. Cell matching (cont.) • Equator trimming length • Make inner cell pair Cij (HCi-HCj), so finally we have the half cell Hi configuration in the 9-cell cavity half cell sequence n • The end cells are tuned separately by the similar method

  22. Dumbbell frequency measurement • Dumbbell π mode and 0 mode frequency • Determine the individual half cell frequency with perturbation method [Sun An etc., RSI 79, 104701(2008)] • 6 frequencies

  23. Pretuning • Pretuning machine under fabrication • Deliver in July 2009 • 9-cell copper cavity for machine test • Machine design parameters • resolution：2μm（9-cellcavity freq. change 600 Hz） • max. clamp plates distance：2cells • max. tuning length：8 mm • max. force：10 kN • displacement sensor：electronic meter • stress sensor：N/A • CW frequency and phase shift measurewith N.A. for field flatness bead pull Ψ f0

  24. Surface Preparation Plan • Install in stainless steel jig • CBP 150μm(must do due to large grain steps, inner surface inspection) • Ultrasonic degreasing and rinsing • First CP and rinsing (inner 80μm, outer 20 μm) • Close loop, acid temperature control • Annealing • Pretuning • Install in vertical test titanium jigand degreasing • Flange CP and Second CP 20μm • Hot bath rinsing (degreaser, H2O2, alcohol for EP)* • HPR and dry in class 10 clean room • Fill with Argon gas (what gaskets?) and shipping to KEK STF

  25. Vertical test issues at KEK STF Hanging holes or hanging rings? • Jig dimension and interfaces • Hanging holes, HPR interface holes • VT hanging stand holes • Pretuning(clamp plates? others?) • CP (must, where to do?) • Annealing (if needed, STF Ti box) • EP(if needed, cathode rod diameter?) • HPR • Input coupler and antenna(use STF’s, coupling check?) • Helix gaskets (reliable but expensive, easy to demount? use STF’s?) • Pumping port transition • T-mapping • Inspection of inner surface (Kyoto camera rod diameter?) HPR VT

  26. Online pumping during vertical test? • At low temperature, the cryo-pumping of the cavity overtakes the online pumping. • Without online pumping, the increased residual gas is 1.25×10-3 Torr·L, which will cause a negligible increment on the adsorbed molecule number of the cavity surface. • Maybe the online pumping can be omitted. • More details in the memo “About online pumping during vertical test” by XIAO Qiong (肖琼) of the vacuum group

  27. Vertical test time and plan • STF available test time (several choices between Oct. and Dec.) : • ? • ? • Drawings (flanges), interfaces and jig fixed: this meeting • Pretuning clamps fabrication: IHEP, July • CP and EP issues: KEK, August • Input coupler and antenna: KEK, June • Helix gasket: KEK, June • Pumping port transition: IHEP, July • T-mapping and inspection: KEK and IHEP, September

  28. Full end group 9-cell cavity design and HOM coupler simulation

  29. Summary • IHEP’s first 9-cell cavity will finish fabrication and EBW in July , and hope to get the first test result at the end of 2009 in collaboration with KEK STF. This will be a milestone. • Large grain niobium cavity fabrication has many special issues, dimension and frequency control is important and needs more investigation. • SCRF facilities upgrade should be promptly driven by the cavity R&D progress and requirement, which is urgent for sustainable R&D at home

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