1. Cavity Degradation Experience at S1-Global
TTC Meeting
Kirk
7/Dec/2011

2. Outline Vertical test and Cryomodule test
Performance improvement and degradation
Optical inspection after S1-Global
Summary
7/Dec/2011
TTC Meeting

3. Vertical test and Cryomodule test
CW operation
Variable coupler with almost no reflection
Several hundred W from RF Amplifier
Cryomodule test
Pulse operation (5Hz/1.5ms)
Variable coupler with total reflection
Several hundred kW from Klystron
The duty factor is considerably different!
7/Dec/2011
TTC Meeting

4. S1-Global Cryomodule Cryomodule-C Cryomodule-A (4 TESLA cavities)
(4 TESLA-like cavities)
7/Dec/2011
TTC Meeting

5. Cavity Performance @V.T.
2 cavities from FNAL
2 cavities from DESY
4 cavities from KEK
8 Cavities for S1-Global (ave. 30 MV/m)
E. Kako
7/Dec/2011
TTC Meeting

6. Cavity performance between V.T. and C.T.
Ave.
Ave. (single cavity)
Ave. (7 cavities)
Two cavity performance was degraded and one cavity improved!
7/Dec/2011
TTC Meeting

7. Cavity performance between V.T. and C.T.
drastic improvement
severe drop!
7/Dec/2011
TTC Meeting

8. MHI#5 on 12/Nov/2010 In this day, we tried the LFD compensation
by Piezo.
But, before that, we had to adjust
the F.B. tuning by LLRF system.
During this adjustment,
the F.B. parameter was not
optimized, and abnormally
input power had been supplied to
this cavity.
Therefore, the vacuum level was
too high, and the vacuum interlock
worked many times with the arc
interlock!
Cavity gradient
12:00
19:00
Vacuum at
warm side
He level
He pressure
He flow
7/Dec/2011
TTC Meeting

9. Optical inspection for MHI#5 after S1-Global
7/Dec/2011
TTC Meeting

10. Optical inspection for MHI#5 after S1-G
3rd
π, 7π/9, 5π/9,
6cell equator, t=320 deg
4π/9,
5cell equator, t=154 deg
7/Dec/2011
TTC Meeting

11. Transition of heating location for MHI#5
1st
2nd
3rd
5π/9 (25.6MV/m)
π, 7π/9, 5π/9, 3π/9
(27.6MV/m)
7π/9 (29.2MV/m)
π, 3π/9
(~29.1MV/m)
4π/9
(20.4MV/m)
6π/9 (32.9MV/m?)
4π/9, 6π/9
(30.7MV/m)
π, 8π/9, 4π/9, 3π/9 (~21.4MV/m)
pre-EP : 5μm
EP1 : μm
EP2 : 50μm
EP2 : 50μm
EP2 : 20μm
7/Dec/2011
TTC Meeting

12. History of defect at 154° in Cell#5
As received
After EP1 25μm
7/Dec/2011
After EP1 100μm
TTC Meeting
After anneal

13. History of defect at 154° in Cell#5
After EP2 and VT
After 2nd EP2 and VT
7/Dec/2011
After S1-G
TTC Meeting

14. History of defect at 320° in Cell#6
As received
After EP1 25μm
7/Dec/2011
After EP1 100μm
TTC Meeting
After anneal

15. History of defect at 320° in Cell#6
After EP2 and VT
After 2nd EP2 and VT
7/Dec/2011
After S1-G
TTC Meeting

16. Optical inspection for MHI#6 after S1-Global
7/Dec/2011
TTC Meeting

17. Optical inspection for MHI#6 after S1-G
6th
4-5 iris, t=255 deg.
3 cell equator , t=9 deg.
5π/9 (35MV/m)
6π/9 (35MV/m)
4π/9, 8π/9, π (28~32MV/m)
4 cell equator , t=103 deg.
7/Dec/2011
TTC Meeting
8-9 iris, t=261~280 deg.

18. Profile of defect at 255° in Iris#4-5
4-5 iris, t=255 deg.
Bump size
50×350[μm]
7/Dec/2011
TTC Meeting

19. History of defect at 255° in Iris#4-5
As received
After bulk EP
After 1st VT
After 2nd VT
After 3rd VT
After S1-G
7/Dec/2011
TTC Meeting

20. History of defect at 261~280° in Iris#8-9
8-9 iris, t=261 deg.
After 3rd VT
After S1-G
8-9 iris, t=270 deg.
After 3rd VT
After S1-G
7/Dec/2011
TTC Meeting

21. History of defect at 261~280° in Iris#8-9
8-9 iris, t=280 deg.
After 3rd VT
After S1-G
7/Dec/2011
TTC Meeting

22. Optical inspection for MHI#7 after S1-Global
7/Dec/2011
TTC Meeting

23. Optical inspection for MHI#7 after S1-G
Top bp, t=324～350 deg.
2nd
3, 43MV/m
Bottom bp, t=214～278 deg.
No defect at every cell
6, 7, 8π/9,
Bottom bp, t=81 deg.
7/Dec/2011
TTC Meeting

24. Problematic EBW at beam pipe
324°
333°
342°
350°
7/Dec/2011
TTC Meeting

25. Problematic EBW at beam pipe
Bottom bp, t=81 deg.
Bottom bp, t=108 deg.
Bottom bp, t=108 deg.
7/Dec/2011
TTC Meeting

26. Problematic EBW at beam pipe
Bottom bp, t=214～278 deg.
214°
223°
232°
242°
251°
261°
270°
278°
7/Dec/2011
TTC Meeting

27. Optical inspection for MHI#9 after S1-Global
7/Dec/2011
TTC Meeting

28. Optical inspection for MHI#9 after S1-G
3rd
4π/9,
2 cell equator , t=222 deg.
7, 8π/9,
5, 6, 7, 8π/9,
8-9 iris, t=94 deg.
9 cell equator , t=317 deg.
7/Dec/2011
TTC Meeting

29. Transition of heating location for MHI#9
1st
2nd
3rd 3,
1st
3, 4, 5, 7, 8π/9,
4π/9,
7, 8π/9,
7, 8π/9, 2nd
5, 6, 7, 8π/9,
pre-EP : 5μm
EP1 : 100μm
EP2 : 20μm
Ethanol+HWR+HPR
EP2 : 20μm
Degreasing(FM-20)
+HWR+HPR
EP2 : 20μm
Degreasing(FM-20)
+HWR+HPR
7/Dec/2011
TTC Meeting

30. History of defect at 222° in Cell#2
As received
After bulk EP
After 1st VT
After 2nd VT
After S1-G
7/Dec/2011
TTC Meeting

31. History of defect at 317° in Cell#9
As received
After bulk EP
After 1st VT
After 2nd VT
After S1-G
7/Dec/2011
TTC Meeting

32. History of defect at 94° in Iris#8-9
As received
After bulk EP
After 1st VT
After 2nd VT
After S1-G
7/Dec/2011
TTC Meeting

33. Summary DESY and FNAL cavities should be also inspected
Two cavity performances were degraded at cryomodule test.
MHI#5 cavity had coupler trouble due to non-optimized F.B. system.
MHI#6 cavity improved largely because of lower duty factor.
Every MHI cavity has several defects at equator, iris or beampipe.
DESY and FNAL cavities should be also inspected
by Kyoto camera after disassembly!
7/Dec/2011
TTC Meeting

34. Thank you for your attention.
7/Dec/2011
TTC Meeting