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Kirk

Improvement of cavity performance by T-mapping/ X-ray-mapping , optical inspection and local grinding. Kirk. Outline. Introduction List of Measured (Fabricating) Cavity Sequence of Cavity Process at STF Recent Cavity Performance 3 Important Items for Evaluation and Improvement

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Kirk

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  1. Improvement of cavity performance by T-mapping/X-ray-mapping, optical inspection and local grinding TTC Meeting 2012 @J-Lab Kirk

  2. Outline • Introduction • List of Measured (Fabricating) Cavity • Sequence of Cavity Process at STF • Recent Cavity Performance • 3 Important Items for Evaluation and Improvement • Examples of Effect of Local Grinding Technique • Summary TTC Meeting 2012 @J-Lab

  3. Measured(Fabricating) Cavities • MHI-01~04 Phase-1 (already done) • MHI-05~09 S1-Global (already done, except for MHI-08) • MHI-10, 11 S0 plan (already done) • MHI-12, 13 Quantum Beam (under beam operation) • MHI-14~22 Phase-2 (CM-1 assembly will start next year) • MHI-23~26 Under fabrication @Mihara • MHI-A, B, C New fabrication method (presented by F. Inoue) • HIT-01, 02 New vendor • TOS-01, 02 New vendor • KEK-00, 01 In house (presented by T. Saeki) • IHEP-01 International Collaboration • AES-001 Commissioning test (first test) TTC Meeting 2012 @J-Lab

  4. Sequence of cavity process as received from a vendor surface treatment (bulk EP∼100μm) f0 & Field flatness measurement Optical inspection annealing surface treatment (light EP ∼20 or 5μm, Degreasing, HPR) F.F. > 96% Optical inspection pre-tuning Two weeks per one cycle ☠ failure Cryomodule test V.T. success TTC Meeting 2012 @J-Lab

  5. Cure for Failed Cavity V.T. T-map X-ray-map Radiation monitor measured at top flange of cryostat optical inspection local grind equator iris EP (20μm) optical inspection After V.T. After local grind After 20μm EP EP (5μm) TTC Meeting 2012 @J-Lab

  6. Items for evaluation / improvement of cavity performance T-mapping/X-ray-mapping Optical inspection (Kyoto Camera) Local Grinding Machine “San-shu No Jingi” (three imperial treasures) TTC Meeting 2012 @J-Lab

  7. T-mapping/X-ray-mapping System 396 carbon resistors 182 PIN photo diodes Radiation monitor TTC Meeting 2012 @J-Lab

  8. Optical Inspection (Kyoto Camera) This tool was developed by Kyoto University and KEK. After some improvements, many defects were observed easily. Before LED improvement After LED improvement TTC Meeting 2012 @J-Lab

  9. Local Grinding Techniques Automatic grinding machine Handy grinding equator HITACHI method iris TTC Meeting 2012 @J-Lab

  10. Categorization of Problematic Defect • Type I : Defect on bead of Equator • Cavity performance is limited certainly (worst case) • Type II : Defect on bead of Iris • Heavy F.E., sometimes with explosive event • Type III : Defect on bead of End-cell/Beam-pipe • F.E., sometimes with explosive event, but not understood well • Type IV : Defect at other location • Not on bead or far away from equator TTC Meeting 2012 @J-Lab

  11. Type I: Defect on bead of Equator MHI-05, 09, 10, 15, 16 and TOS-02 were limited by Type I. MHI-05 MHI-09 MHI-10 23.8MV/m 27.1MV/m 27.0MV/m MHI-15 MHI-16 TOS-02 22.5MV/m 20.8MV/m 31.2MV/m TTC Meeting 2012 @J-Lab

  12. Type II: Defect on bead of Iris MHI-06, 09, 14, 15, 18, 19, 20, 22 and HIT-02 were limited by Type II. MHI-14 MHI-15 MHI-18 18.1MV/m (explosion) 9.7MV/m 20.8MV/m (explosion) MHI-20 MHI-22 MHI-09 27.0MV/m (explosion) 31.5MV/m 9.0MV/m When a cavity has such a defect at iris region, the heavy field emission occurs certainly. TTC Meeting 2012 @J-Lab

  13. Type III: Defect on bead of End-cell/Beam-pipe Type III probably limited the performance of MHI-07, 11, 18 and 19. Not understood whether these defects are actually problematic, or not. 251° 214° MHI-07 MHI-11 MHI-18 18.1MV/m (explosion) 261° 223° 270° 232° MHI-19 278° 242° TTC Meeting 2012 @J-Lab

  14. Type IV: Defect at other location MHI-08, 15 and TOS-02 were limited by Type IV. MHI-08 MHI-15 TOS-02 31.5MV/m 17.0MV/m 38.2MV/m Irregular pit (edge of equator bead) Bump shape Bump shape Sputtered ball? MHI-08 had the rare defect after 1st V.T. The defect shape is like a triangle and deep pit. MHI-15 and TOS-02 had a bump defect somewhat away from equator. They are considered as the sputtered ball during the EBW process. TTC Meeting 2012 @J-Lab

  15. Improvement of cavity performance by local grind MHI-14 MHI-15 23  36 MV/m 15  37 MV/m 35  41 MV/m MHI-20 HIT-02 Best record in STF 9  35 MV/m The radiation level also decreased drastically! TTC Meeting 2012 @J-Lab

  16. Summary of Effect of Local Grind at STF TTC Meeting 2012 @J-Lab

  17. Summary of Effect of Local Grind at STF TTC Meeting 2012 @J-Lab

  18. Summary of Effect of Local Grind at STF The local grinding technique is very important for the improvement of cavity performance!! TTC Meeting 2012 @J-Lab

  19. Summary of cavity affected by defect MHI-12, 13, 17 and 21 had no problematic defect, and they reached the ILC specification easily! But, the other cavities had the problematic defect, which is categorized to Type I, II, III and IV. And, we had to remove these defects for the improvement of the cavity performance by the local grinding method, because these defects are never removed by the EP. † Yellow shows the cavity without problematic defect. For only Type I, we can evaluate the correlation between the quench field and the defect profile. But, it is difficult to evaluate by the same way for the other three types. TTC Meeting 2012 @J-Lab

  20. Q0 – Eacc Curve for STF-2 Cavities MHI-12, 13, 17 and 21 reached the ILC specification without any grinding, because of no problematic defect. TTC Meeting 2012 @J-Lab

  21. Max. Achievable Gradient of MHI/HIT TTC Meeting 2012 @J-Lab

  22. Max. Achievable Gradient of MHI/HIT 40.7 36.2 36.6 35.7 33.8 38.4 36.2 37.2 35.1 38.9 35.8 40.9 MV/m EP EP EP EP LG+EP LG+EP LG+EP LG+EP LG+EP LG+EP LG+EP LG+EP TTC Meeting 2012 @J-Lab

  23. Comparison of radiation level for EP / LG+EP only EP (partly L.G.+EP) cavities only L.G.+EP cavities TTC Meeting 2012 @J-Lab

  24. Summary • Cavity R&D has been carried out since 2008 at STF. • For evaluation of cavity performance, T-mapping/X-ray-mapping and optical inspection system are very important. • For improvement of cavity performance, local grinding technique is effective, and also suppression of F.E. • Problematic defect is categorized to four types. TTC Meeting 2012 @J-Lab

  25. Thank you for your attention TTC Meeting 2012 @J-Lab

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