Performance Degradation in Testing STF2 Cryomodule Cavity Group

Performance Degradation in Testing STF-2 Cryomodule Cavity Group: E. Kako, T. Shishido, K. Umemori, T. Kubo, T. Konomi, G. Park, T. Saeki, T. Dohmae, M. Egi, Kirk RF Group: T. Matsumoto, T. Miura, T. Takenaka, S Michizono 22/Feb/2017 WG 2 in TTC Meeting 2017 @MSU Kirk 1

superconducting rf test facility Brief remark n Degradation from Vertical test to Cryomodule test n Typical case n Degradation in testing Cryomodule n Not typical case, at least in STF n First observation in 3 rd cool-down test for STF-2 CMs 22/Feb/2017 WG 2 in TTC Meeting 2017 @MSU 2

Brief History for STF-2 Cryomodule superconducting rf test facility Date Content 2011 ~ 2013 V. T. for 12 cavities / RF conditioning for 12 couplers Jun/2013 Cleaning up STF tunnel Jul/2013 ~ Apr/2014 Cavity string assembly (three times) Oct/2013 ~ Jan/2014 Module assembly (CM 1/CM 2 a) Jul/2014 Complete certification for High pressure Gas Code Oct/2014 ~ Dec/2014 1 st cool-down / low power test Apr/2015 ~ Jul/2015 5 MW Klystron / Single waveguide system completed Jul/2015 ~ Sep/2015 Coupler conditioning at room temperature Oct/2015 ~ Dec/2015 2 nd cool-down / high power test Jan/2016 ~ Jul/2016 Multi-beam Klystron & Waveguide system completed Jul/2016 ~ Sep/2016 Coupler conditioning at room temperature Sep/2016 ~ Nov/2016 3 rd cool-down / LFD, Q 0 measurement, 8 Cavities Operation & LLRF study F. Y. 2017 4 th cool-down test (? ) F. Y. 2018 ~ Beamline construction / Beam operation starts (? ) 22/Feb/2017 WG 2 in TTC Meeting 2017 @MSU 3

STF-2 Accelerator Layout superconducting rf test facility To be constructed CM 2 a Cold box CM 1 Waveguide system Capture CM View from downstream To be constructed Cold box Chicane RF Gun 22/Feb/2017 WG 2 in TTC Meeting 2017 @MSU View from upstream 4

Summary of Cavity Performance superconducting rf test facility Not measured in 3 rd C. T. Kt for CAV#1 and #8 was never changed! 22/Feb/2017 Significantly degraded in 3 rd C. T. WG 2 in TTC Meeting 2017 @MSU 5

Change of Cavity Performance in STF-2 superconducting rf test facility 3 rd cooldown test All measured cavities in Capture/STF-2 CMs had performance degradation again! Uniformly degraded! Not measured cavities in 3 rd C. T. 2 nd cooldown test 22/Feb/2017 WG 2 in TTC Meeting 2017 @MSU 6

Consideration of More Degraded Cavities superconducting rf test facility n Change of RF System n Generally, some systematic errors exist between different RF systems n Too High Forward Power distributed to Power Coupler n After power adjustment, distributed power changed from 400 k. W to 260 k. W n Earthquake? n We have experienced by Level 4 earthquakes many times in these years 22/Feb/2017 WG 2 in TTC Meeting 2017 @MSU 7

RF System changed from 2015 to 2016 superconducting rf test facility Single Cavity Operation in 2015 8 Cavities Operation in 2016 800 k. W Klystron (Distributed RF System) 10 MW Multi-beam Klystron Ø Ø 22/Feb/2017 Klystron Waveguide Circulator LLRF modules WG 2 in TTC Meeting 2017 @MSU 8

Too High Forward Power distributed superconducting rf test facility After optimization of LLRF control, forward power was drastically reduced! Red: Gradient Blue: Forward Power Green: Reflect Power 22/Feb/2017 Bump in RF filling disappeared after parameter optimization! Max. level changed from 400 to 260 k. W. We have never observed strange phenomena in vacuum level during this operation. WG 2 in TTC Meeting 2017 @MSU 9

Earthquake? (Unbelievable, but…) superconducting rf test facility 1 st cooldown test in STF-2 CM 2 nd cooldown test in STF-2 CM 3 rd cooldown test in STF-2 CM 22/Feb/2017 Date Magnitude Level in Tsukuba city 11/Mar/2011 14: 46 M 7. 9 Level 6 14/Mar/2012 21: 05 M 6. 1 Level 4 28/Jan/2013 3: 41 M 4. 9 Level 3 20/Sep/2013 2: 25 M 5. 9 Level 3 10/Nov/2013 7: 37 M 5. 5 Level 4 31/Dec/2013 10: 03 M 5. 4 Level 3 16/Sep/2014 12: 28 M 5. 6 Level 4 25/May/2015 14: 28 M 5. 5 Level 4 12/Sep/2015 5: 49 M 5. 2 Level 3 16/May/2016 21: 23 M 5. 5 Level 4 27/Jul/2016 23: 47 M 5. 4 Level 3 22/Nov/2016 5: 59 M 7. 4 Level 4 28/Dec/2016 21: 38 M 6. 3 Level 4 WG 2 in TTC Meeting 2017 @MSU 10

In 4 th cooldown test…, F. Y. 2017 -2018? superconducting rf test facility Ø Re-check cavity performance Ø Re-check radiation level from each cavity Ø Re-check Kt (Qtra) 22/Feb/2017 WG 2 in TTC Meeting 2017 @MSU 11

superconducting rf test facility Summary l First observation for performance degradation in testing STF-2 cryomodule l No reason for the phenomenon at present l Re-check cavity performance in next cooldown test 22/Feb/2017 WG 2 in TTC Meeting 2017 @MSU 12

superconducting rf test facility Back-up slides 22/Feb/2017 WG 2 in TTC Meeting 2017 @MSU 13

Cavity performance in CM 1/CM 2 a superconducting rf test facility CM 1 Module # String # CM 2 a 1 2 3 Cavity # 1 2 3 4 5 6 7 8 9 10 11 12 Cavity name MHI-14 MHI-15 MHI-17 MHI-18 MHI-19 MHI-20 MHI-21 MHI-22 MHI-24 MHI-23 MHI-25 MHI-26 >36. 6 35. 7 >38. 4 >36. 2 37. 2 Eacc @Last V. T. [MV/m] Eacc @2 nd cooldown test (short pulse) (power limit) >38. 6 (admin. stop) (power limit) 36. 8 35. 2 >36. 1 (Cell#1 Quench) (Quench) (Pf max. ) (Cell#1 Quench) >35. 1 >38. 9 >35. 8 >12. 0 (power limit) 26. 6 20. 0 25. 0 (Quench) (power limit) (admin. stop) >36. 2 >18. 0 (admin. stop) 35. 9 32. 3 31. 6 (Cell#3 Quench) (Cell#1 Quench) 33. 6 32. 1 31. 5 (Quench) [MV/m] Eacc @2 nd cooldown test (full pulse) >38. 7 (admin. stop) 36. 7 35. 3 (Quench) >36. 3 >26. 0 (admin. stop) 16. 4 24. 6 (Quench) >32. 3 >18. 1 (admin. stop) 34. 1 33. 2 32. 4 (Quench) 31. 5 27. 7 31. 5 30. 8 26. 8 [MV/m] Eacc @3 rd cooldown test (full pulse) >36. 8 (admin. stop) 36. 4 33. 4 (Quench) 35. 4 28. 0 (Quench) 31. 6 (Quench) [MV/m] 22/Feb/2017 WG 2 in TTC Meeting 2017 @MSU 14

Cavity performance in Capture CM superconducting rf test facility Module # String # Cavity name Eacc @Last V. T. [MV/m] Eacc in 2012 (600μs) [MV/m] Eacc in 2012 (1500μs) [MV/m] Eacc in 2016 (1650μs) [MV/m] 22/Feb/2017 Capture 1 1 MHI-12 >40. 7 (power limit) 35. 3 (Quench) 30. 6 (Quench) 28. 7 (Quench) 2 MHI-13 32. 2 (Cell#2 Quench, Heavy F. E. ) 32. 5 (Quench) 32. 2 (Quench) 29. 8 (Quench) WG 2 in TTC Meeting 2017 @MSU 15

Summary of radiation level in CM test superconducting rf test facility Short pulse (900+100μsec) Full pulse (900+800μsec) 空洞直下で測定した放射線量の比較(ただしCavity#10以降は固定)。 MAR-781/-782 22/Feb/2017 Radiation level is measured below the cavity, upstream and downstream of beampipe. Field emission is observed for every cavity. Especially, cavity #5, #6, #7 and #9 had heavy F. E. There was no radiation in full pulse mode for Cavity #6. Because, Cavity #6 was limited by HOM heating before field emission. But, as you see the short pulse mode, it was comparable with Cavity #5 and #7. WG 2 in TTC Meeting 2017 @MSU 16

Positions of radiation detector superconducting rf test facility never moved upstream downstream Monitors at ground level never moved MAR-782 CM 2 a CM 1 MAR-781/-782 MHI-26 MHI-25 MHI-23 MHI-24 MHI-22 MHI-21 MHI-20 MHI-19 MHI-18 MHI-17 MHI-15 MHI-14 never moved cavity MAR-781 Injector CM The cable length is different between MAR-781 and MAR-782. MAR-781 is shorter, and then could not be put at the end of CM 2 a. MHI-13 MHI-12 MAR-781/-782 22/Feb/2017 WG 2 in TTC Meeting 2017 @MSU 17

Positions of radiation detector in CM 2 a superconducting rf test facility MAR-782 cavity downstream never moved CM 2 a upstream never moved CM 1 MAR-781/-782 MAR-782 MHI-26 MHI-25 MHI-23 MHI-24 MHI-22 MHI-21 MHI-20 MHI-19 MHI-18 MHI-17 MHI-15 MHI-14 never moved cavity MAR-781 Injector CM never moved For MHI-23, -25 and -26, MAR-781 is not the position below the cavity. MHI-13 MHI-12 MAR-781 Cavity#10以降の高感度モニターはケーブル長が足りないため空洞直下に設置できなかった。 同様に、下流側の高感度モニターもモジュール設置用の台座に設置せざるを得なかった。 22/Feb/2017 WG 2 in TTC Meeting 2017 @MSU 18