Status of Vertical Tests of SSR1 Cavities A. Sukhanov for the - - PowerPoint PPT Presentation

• A. Sukhanov

for the group of testers:

• T. Khabiboulline, D. Sergatskov, O. Melnychuk,
• Y. Pischalnikov,
• M. Hassan, L. Ristori, A. Rowe, I. Terechkine

Status of Vertical Tests of SSR1 Cavities

Cavity Processing prior Vertical Test

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• 1. Incoming QC/QA

a. Visual inspection

• b. CMM
• c. RF QC

d. Vacuum leak check

• 2. US degreasing/UPW rinse
• 3. Bulk BCP (60+60 um)
• 4. US degreasing/UPW rinse
• 5. HPR in B101 to prepare for H2 degassing
• 6. 600C bake 10h plateau in MP9 oven
• 7. RF tuning
• 8. US degreasing/UPW rinse
• 9. Light BCP (20-30 um)
• 10. HPR in G150 (horizontal)
• 11. HPR in B101 (vertical)
• 12. Cleanroom assembly
• 13. Evacuation/leak check (10-10 mbar-l/s or better)
• 14. 120C vacuum bake in IB1 or MP9 120C ovens (24h hold minimum)

Allan Rowe

• 4 weeks to process one cavity
• Few cavities can be processed in

pipeline

Cavity Processing prior Vertical Test

• 120C bake is beneficial for removing water from the cavity surface
• Shortens multipactor processing time during cold test
• Possible reduction of Q0 by 30-40%?
• Improvised 120C bake in IB1 using blankets and Al foil
• 105,107,108 (1st test) & 109

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Allan Rowe

• 4"

SKIRT FLAP SKIRT FLAP DELRIN CLIP STRAP TYP CLOSING SEAM FLAP TYP

JACKET #1 JACKET #2 JACKET #3

TYP ZONE "A" SENSORS TYP ZONE "B" SENSORS PWR LDS TOP CAP

+ =

Cavity Processing prior Vertical Test

• 120C oven in MP9
• 110 & 108 (2nd test)

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Allan Rowe

Preparation of SSR1 Cavity for Vertical Test in IB1

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Pictures courtesy of Dmitri Sergatskov

Cavity mounted on top plate Cage and Pinc coupler Installation of the 2nd sound system

SSR1 Vertical Test Typical Sequence

• Multipactor conditioning
• Usually at 4.4 K to save LHe
• Cool-down from 4.4 K to 2 K
• Keep cavity on resonance at low field (3-5 MV/m)
• Measure df/dp and Q0 vs T
• Cavity performance evaluation at 2 K
• Q0 vs Eacc
• Maximum field, Q0 and radiation at maximum field
• approximate quench location w/ SS system
• FE (if present) onset field
• Additional studies
• Induced quench studies (Dmitri & Iouri T.)

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Multipactor Conditioning

• S1H-NR-105

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Time elapsed, h 00:00 02:00 04:00 06:00 08:00 10:00 , MV/m ! " /

acc

=V

acc

E 2 4 6 8 10 12 14

S1H-NR-105 (no 120C bake): March 27, 2012 (4.4K) S1H-NR-105 (120C bake): April 16, 2012 (2K) S1H-NR-105 (HPR, 120C bake): June 23, 2012 (4.4K)

MP is present after 10 h FE & MP are present after 6 h of processing Cleaned MP after 3 h Passed MP barrier after 3 h

Multipactor Conditioning

• S1H-NR-107 & S1H-NR-108

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Time elapsed, h 00:00 02:00 04:00 06:00 08:00 10:00 , MV/m ! " /

acc

=V

acc

E 2 4 6 8 10 12 14

S1H-NR-107 : July 27, 2012 (4.4K) S1H-NR-108 : October 30, 2012 (4.4K) S1H-NR-108 (HPR): January 16, 2013 (4.4K)

Cleaned MP after 3.5 h MP is present after 9 h processing Cleaned MP after 4 h

Multipactor Conditioning

• S1H-NR-109 & S1H-NR-110

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Time elapsed, h 00:00 02:00 04:00 06:00 08:00 10:00 , MV/m ! " /

acc

=V

acc

E 2 4 6 8 10 12 14

S1H-NR-109 (HPR): November 13, 2012 (4.4K) S1H-NR-110 (HPR): January 8, 2013 (4.4K)

Cleaned MP after 9 h MP is present after 11 h of processing

Frequency vs Pressure, df/dp Measurements

• Average df/dp is about -650 Hz/Torr at 2 K (unconstrained cavity)

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LHe Pressure, Torr 100 200 300 400 500 600 700 800 900 1000 f, MHz !

• 0.2
• 0.1

0.1 0.2 0.3 0.4

1.9) Hz/Torr ± S1H-NR-108, January 16, 2013: dF/dP = ( -683.1 8.5) Hz/Torr ± S1H-NR-108, November 1, 2012: dF/dP = ( -625.8 5.6) Hz/Torr ± S1H-NR-105, June 27, 2012: dF/dP = ( -451.8 1.9) Hz/Torr ± S1H-NR-105, March 29, 2012: dF/dP = ( -645.4

Q0 vs T Measurements

• Rs=G/Q0, G=84 Ohm for SSR1

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T, K 1 1.5 2 2.5 3 3.5 4 4.5 5 ! , n

s

R 10 20 30 40 50 60 70 80

! 0.2) n ± = ( 6.4 S1H-NR-108, November 1, 2012; R ! 0.1) n ± = ( 8.5 S1H-NR-105, June 27, 2012; R ! 0.1) n ± = ( 6.0 S1H-NR-105, March 29, 2012; R

T "

• exp

T C + (T) = R

s

Fit to: R

Q0 and Radiation vs Field at 2K

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, MV/m ! " /

acc

=V

acc

E 5 10 15 20 25 Q

9

10

10

10

11

10 Radiation, mR/h

• 2

10

• 1

10 1 10 , MV/m

pk

E 10 20 30 40 50 60 70 80 90 , mT

pk

B 20 40 60 80 100 120 140

• solid marker, X-ray - empty marker

Q S1B-RK-102: March 3, 2009 S1H-NR-105: June 27, 2012 S1H-NR-107: July 30, 2012 S1H-NR-109: November 14, 2012 S1H-NR-108: January 16, 2013 PX specifications

Q0 at Low Field, 2K

• Some gradual improvement in Q0 (residual resistance) from earlier to

later tests

• Improvement (or drift) in processing/preparation of cavities?

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Cavity Test date Q0 @ 3 Mv/m, ×1010 R0*), nΩ

S1H-NR-105 June 27, 2012 0.95 8.0 S1H-NR-107 July 30, 2012 1.02 7.4 S1H-NR-109 November 14, 2012 1.22 6.1 S1H-NR-108 January 16, 2013 1.54 4.7

*) we assume here that RBCS(2K) = 0.8 nΩ

S1H-NR-110 Test Results at 2K

• Q0 ~ 1.3×1010 at low field
• Strong FE turn on at 8.5 MV/m
• Maximum field achieved 13.7 MV/m (power

limited)

• Radiation ~1 mR/h
• Observed excitation of 1588 MHz HOM

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(effective cavity length 135 mm)

Summary and Plans

• Cavity processing procedure is established
• 8 vertical tests of 5 SSR1 cavities
• 105 tested 3 times, 108 tested twice
• 4 cavities (105, 107, 108 & 109) qualified for PXIE cryomodule
• observed some gradual improvement in Q0 from earlier to last tests
• 110 performance limited by FE
• optical inspection (using borescope) in clean room
• RF measurements
• (light BCP)
• HPR
• retest
• Vertical tests of the rest of available SSR1 cavities
• 113 & 110 (March)
• 111, 112 & 114 (April-May)

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