1. Recent VT Results in the STF-2 cavities
Outline
STF cavities
VT results
Summary
STF Cavity Group: H. Hayano, E. Kako, S. Noguchi,
M. Satoh, T. Shishido, Y. Yamamoto and K. Watanabe
Kirk
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2. Outline Facility status at STF
MHI#12 and #13 achieved ILC specification
Very recent results of MHI#14 and #15
Summary
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3. STF location South East West North ATF/ATF2 STF
SC cavity fabrication facility
East
West
ATF/ATF2
STF
North
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4. Outline of STF Cryogenic liquefier EP No.2 tunnel underground
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5. Fabricated(ing) 9-cell cavities
MHI#1-#4 (STF Phase-1)
MHI#5-#9 (S1-Global)
MHI#8 was sent to J-Lab for S0 plan!
MHI#10, #11 (S0)
MHI#12, #13 (Quantum Beam Project)
HIT#1 (New vendor)
TOS#1 (New vendor)
IHEP#1 (International Collaboration)
MHI-A (for cost reduction study)
MHI#14~#22 (STF Phase-2)
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6. Typical Process for Vertical Testing
as received from a vendor
f0 & Field flatness measurement
surface treatment
(bulk EP∼100μm)
Optical inspection
annealing
>96%
surface treatment
(light EP ∼20μm, degreasing, HPR)
Optical inspection
pre-tuning
Two weeks per one cycle ☠
failure
Cryomodule test
V.T.
success
Cavity string
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7. Cavity diagnostic system at STF
396 carbon resistors
182 PIN photo diodes
8 second sound sensors
Radiation monitor
Electron probe
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8. MHI#12 and #13 achieved ILC spec.☺
MHI#12 1st VT
MHI#12 2nd VT ☺
MHI#13 1st VT
MHI#13 2nd VT
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9. Radiation level They are perfect cavities! Every data Only recent data
Radiation level for MHI#12 and #13 was very low!
They did not have any defect and problematic EBW bead.
They are perfect cavities!
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10. Case of MHI#14
1st V.T.
2nd V.T.
26.0MV/m
 14.1MV/m
25.9MV/m
 12.4MV/m
15.0MV/m
Cell #8 heating
13.0MV/m
Cell #8 heating
We observed the same situation between 1st and 2nd V.T.
Around 26MV/m in the first power rise,
explosion occurred and radiation level became much higher.
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11. Case of MHI#14 Radiation monitor 1st power rise @π mode
After the explosive event,
the radiation level was much higher.
The signals from PIN diodes at top flange
were also drastically changed.
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12. Case of MHI#14 1st V.T. Typical case of field emission 4π/9 @29MV/m
280°
Iris between cell #8 and #9
Making replica
After manual grind, it disappeared!
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13. Case of MHI#14 4π/9 2nd V.T. T-mapping X-ray-mapping 34MV/m
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14. Case of MHI#14 6π/9 2nd V.T. T-mapping X-ray-mapping 30MV/m
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15. Case of MHI#11 Explosion occurred! After the 3rd V.T.,
we observed the problematic EBW bead
at the connection between the end cell
and the beam pipe.
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16. Case of MHI#15 1st V.T. 2nd V.T. Will be tested on this Thursday
22.5MV/m
Cell #2 heating
We expected any defect is found around heating location at Cell #2,
because of the low quench field.
 That was true!
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17. Case of MHI#15 Local grind Nothing was found! Disappeared! 62°π,
Local grind
5π/9,
Nothing was found!
Disappeared!
This cavity will be tested on this Thursday.
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18. Case of MHI#10 5~9π/9 @20~21MV/m 4π/9 @24MV/m 3π/9 @41MV/m
323°(300μmx15μm)
310°(250μmx15μm)
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19. Achieved Gradient at STF
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20. Final Q0-Eacc curve at STF
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21. Summary MHI#12 and #13; Perfect cavities
MHI#10 and #15; Defect “just” on EBW bead
MHI#11 and #14; Explosive event occurred due to problematic EBW bead (probably)
MHI#16 and #17; Will be tested before summer
MHI#18-#22; Will be tested after summer
We are still studying the performance of 9cell cavity for ILC.
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22. Thank you for your attention!
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