1 / 20

Explosive Events during V.T. in KEK

Explosive Events during V.T. in KEK. Sequence of cavity process. as received from a vendor. surface treatment (bulk EP ∼100 μ m ). f 0 & Field flatness measurement. Optical inspection. annealing. F.F. > 96%. surface treatment (light EP ∼ 2-20 μ m , Degreasing, HPR ). pre-tuning.

curran-anderson
Download Presentation

Explosive Events during V.T. in KEK

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Explosive Events during V.T. in KEK

  2. Sequence of cavity process as received from a vendor surface treatment (bulk EP∼100μm) f0 & Field flatness measurement Optical inspection annealing F.F. > 96% surface treatment (light EP ∼2-20μm, Degreasing, HPR) pre-tuning Optical inspection ☠ failure Cryomodule test V.T. success

  3. MHI-14

  4. Q0-Eacc Curve for MHI #14 @1.8K & 4.2K 26.0MV/m  14.1MV/m 15.0MV/m Cell #8 heating 9.1MV/m power limit

  5. Radiation Level in π mode measurement @2K

  6. Iris between Cell#8-#9 278°

  7. At this time, we didn’t believe this defect was problematic. Then, we did the same surface treatment, not local grinding.

  8. Q0-Eacc Curve for MHI #14 @1.8K & 4.2K 25.9MV/m  12.4MV/m 13.0MV/m Cell #8 heating 9.0MV/m power limit

  9. Radiation Level in π mode measurement @2K

  10. History of Iris 280° between Cell#8-#9 1st V.T.後 EP1後 よく見ると兆候はある 2nd V.T.後 Still there!

  11. At this time, we believe this defect was problematic. Then, we did the local grinding for the removel.

  12. Q0-Eacc Curve for MHI #14 @1.8K & 4.2K 36.6MV/m Power limit 36.5MV/m Power limit 8.5MV/m power limit

  13. Radiation Level in π mode measurement @2K

  14. MHI-15

  15. Q0-Eacc Curve for MHI #15 @1.8K & 4.2K Qt = 6.81 x 1010→ 6.42 x 1010 32.3MV/m He pressure 33.5MV/m  18.4MV/m Explosive event occurred 18.1MV/m Self-pulse 9.5MV/m power limit

  16. Radiation Level in π mode measurement @2K

  17. 3-4 iris, θ=261~262° 8-9 iris, θ=277~286°

  18. 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 certainly occurs.

  19. What is different between DESY and KEK? In KEK, only EP process is used, never BCP. Problematic defect appears suddenly after EP. It can not be removed by only EP (HPR), because of the mechanical structure. I doubt the BCP as one possibility.

  20. Thank you for your attention.

More Related