1. FOR SUPERCONDUCTIVE CAVITIES
A RD 05:
SURFACE PREPARATION
STUDIES
FOR SUPERCONDUCTIVE CAVITIES
F. Eozénou, T. Saeki
18 janvier 2019
- F. Eozénou, T. Saeki FJPPL A_RD_05

2. PARTICIPANTS Irfu KEK Leader: Eozénou Fabien Takayuki Saeki
Members
Irfu
KEK
Leader:
Eozénou Fabien
Takayuki Saeki
Visentin Bernard
Hitoshi Hayano
Berry Stéphane
Ken Watanabe
Antoine Claire
Shigeki Kato
Gasser Yves
Michiru Nishiwaki
Kenji Ueno
Motoaki Sawabe
Yoshisato Funahashi
18 janvier 2019
- F. Eozénou, T. Saeki FJPPL A_RD_05

3. OUTLINE CONTEXT RESULTS ACHIEVED ON SINGLE-CELL CAVITY
SURFACE ANALYSIS ON SAMPLES
CONTINUED EXPERIMENTS
18 janvier 2019
- F. Eozénou, T. Saeki FJPPL A_RD_05

4. CONTEXT
18 janvier 2019
- F. Eozénou, T. Saeki FJPPL A_RD_05

5. MAIN ISSUE FOR ILC → More R&D is necessary to overcome these issues
ILC is in the Technical Design Phase.
The goal of GDE S0 task is to achieve high gradient >35MV/m with yield >90% by the end of 2012
Main reasons for gradient limitation:
Field emission
Early quench (thermal transition)
→ More R&D is necessary to overcome these issues
= IMPROVEMENT OF THE SURFACE TREATMENT:
Electro-Polishing (EP) and post EP treatments.
18 janvier 2019
- F. Eozénou, T. Saeki FJPPL A_RD_05

6. + PROGRAM FOR VERTICAL EP FACILITY AT SACLAY
ELECTRO-POLISHING (EP) FACILITIES
AT KEK (STF) AND SACLAY
9Cell EP set-up at KEK
1Cell EP set-up at Saclay
+ PROGRAM FOR VERTICAL EP FACILITY AT SACLAY
18 janvier 2019
- F. Eozénou, T. Saeki FJPPL A_RD_05

7. DESIGN OF A VERTICAL EP FACILITY AT SACLAY
To be used in:
18 janvier 2019
- F. Eozénou, T. Saeki FJPPL A_RD_05

8. SET-UP AND PREPARATION AREA
18 janvier 2019
- F. Eozénou, T. Saeki FJPPL A_RD_05

9. VARIOUS ANALYSIS TOOLS AT KEK
(XPS, Auger/AES, SIMS, Sputtering, etc..)
Surface Analyses (XPS)　elemental analysis（>He), chemical analysis
Surface Analyses (Auger/AES)　elemental analysis（>He)
Surface Analyses (SIMS)　elemental analysis（all)
Surface Conditioning (Electron Irradiation, Sputtering, Heating)
Electron
Argon
18 janvier 2019
- F. Eozénou, T. Saeki FJPPL A_RD_05 9

10. RESULTS ACHIEVED WITHIN THE COLLABORATION
SURFACE TRATMENTS ON 1-CELL CAVITY
18 janvier 2019
- F. Eozénou, T. Saeki FJPPL A_RD_05

11. CHEMICAL REACTIONS DURING EP: SULFUR IS GENERATED-
SO42- S
Al 3+ H+
Nb5+ +
18 janvier 2019
- F. Eozénou, T. Saeki FJPPL A_RD_05

12. FIELD EMISSION IS STILL A MAJOR ISSUE
→ Necessary to improve contaminants removal on cavities
18 janvier 2019
- F. Eozénou, T. Saeki FJPPL A_RD_05

13. SET-UP FOR SPONGE WIPING ON SINGLE-CELL
Poly-Ethylene (PE) sponge
wipe handle
Sponge mechanics
Insertion
Sponge Expansion
and
Wipe by rotation
UPW + detergent inlet
UPW + detergent outlet
PE sponge
18 janvier 2019
- F. Eozénou, T. Saeki FJPPL A_RD_05 13

14. SPONGE-WIPE TESTED ON « GOOD » CAVITY
Does Sponge-Wipe induce Field-Emission?
→Tested on 1DE1 which quenches without FE.
18 janvier 2019
- F. Eozénou, T. Saeki FJPPL A_RD_05

15. SPONGE-WIPE RECIPE AT KEK
Poly-Vinyl-Chloride (PVC) sponge was set to the sponge-wipe tool. (Poly-Ethylene sponge was used in the fitting test of sponge-wipe tool in 2008.)
Insertion of sponge-wipe tool into the cavity (D1DE1).
Filling FM-20 (5%) into the cavity.
Rotation of sponge-wipe tool (clockwise 20 times + anti-clockwise 20 times) x 2
=== In the fitting test in 2008, we only performed clockwise rotation. Anti-clockwise rotation was applied for the first time and this caused a failure in this test. ===
Draining FM-20 (5%) from the cavity
Running U.P.W. into the cavity and rotation of sponge-wipe tool (clockwise 20 times + anti-clockwise 20 times) x 2.
Draining U.P.W. from the cavity.
Removing the sponge-wipe tool from the cavity.
Running U.P.W. into the cavity in a Ultrasonic hot-water bath at 500C for 1 hour.
HPR for 1 hour.
Drying the cavity in the clean-room.
18 janvier 2019
- F. Eozénou, T. Saeki FJPPL A_RD_05 15

16. SPONGE-WIPE TOOL SCRATCHED THE IRIS
Mistake occured during 1DE1 Sponge-Wipe Cleaning
18 janvier 2019
- F. Eozénou, T. Saeki FJPPL A_RD_05 16

17. DETERIORATION OF THE SURFACE
Iris EBW seam.
Scratched part.
+ Aluminum traces
BP side
Cell
side
18 janvier 2019
- F. Eozénou, T. Saeki FJPPL A_RD_05

18. ORIGINS OF THE SCRATCH
Screw joint was unscrewed during anti-clockwise rotation of sponge-wipe tool.
After sponge-wipe process, we found that the lower part of sponge-wipe tool axis had been unscrewed and been disassembled inside the cavity during the wiping process.
18 janvier 2019
- F. Eozénou, T. Saeki FJPPL A_RD_05 18

19. What happened during the sponge-wipe process
UPW + detergent outlet
Sponge mechanics
Insertion
UPW + detergent inlet
This iris part was scratched by the aluminum structure of sponge-wipe tool.
wipe handle
This end was free during the sponge-wipe process.
Sponge Expansion
and
Wipe by rotation
18 janvier 2019
- F. Eozénou, T. Saeki FJPPL A_RD_05 19

20. SULFURIC ACID RINSING AS A CURE?
Field Emission
A part of the aluminum has been removed, but not sufficient to cure the cavity.
→ Local Grinding of the cavity (Cavity shipped to KEK).
18 janvier 2019
- F. Eozénou, T. Saeki FJPPL A_RD_05

21. LOCAL GRINDING AT KEK Head : Diamond seat CCD camera＋LED
Motor (3000 rpm)
CCD camera＋LED
Scratches on iris
After grinding
Grinding machine
18 janvier 2019
- F. Eozénou, T. Saeki FJPPL A_RD_05 21

22. (PARTIAL) RECOVERY AFTER LOCAL GRINDING OF THE CAVITY
Field Emission
→ Needs additional treatment for further improvement (EP?)
→ Cavity is sent back to KEK
18 janvier 2019
- F. Eozénou, T. Saeki FJPPL A_RD_05

23. Temperature-Mapping was done during Test.
ANALYSIS OF 1DE1 CAVITY
Temperature-Mapping was done during Test.
Feb. 2010
at Saclay
T-map heating location
= Equator marked position
KEK Optical Inspection setup
18 janvier 2019
- F. Eozénou, T. Saeki FJPPL A_RD_05

24. INSPECTION OF THE HEATING ZONE AT KEK
9mm
No suspicious deffect is found at the heating zone.
→ Additional EP at KEK for total performance recovery
12mm
18 janvier 2019
- F. Eozénou, T. Saeki FJPPL A_RD_05

25. STAIN PROBLEM AT STF/KEK AFTER EP
Brown spot and traces are sometimes observed at KEK after Horizontal EP
Typical stains observed after EP (Kyoto-camera inspection)
picture examples using new LED illumination
Problem with the rinsing protocol?
Problem due to the fresh EP mixture?
18 janvier 2019
- F. Eozénou, T. Saeki FJPPL A_RD_05 25

26. clear brown stain cell side beam pipe side EBW seam
ID number 1
STAINS PROBLEM ON 1DE1
downstream Iris
~270degree
clear brown stain
1.3 mm
faint brown stain
cell side
beam pipe side
EBW seam
18 janvier 2019
- F. Eozénou, T. Saeki FJPPL A_RD_05

27. STAIN RECORD of 1DE1-cavity
STAIN PROBLEM SOLVED!
Stains are removed after refinement of the rinsing procedure.
18 janvier 2019
- F. Eozénou, T. Saeki FJPPL A_RD_05

28. SURFACE ANALYSIS ON SAMPLES
18 janvier 2019
- F. Eozénou, T. Saeki FJPPL A_RD_05

29. EFFECT OF POTENTIAL ON CONTAMINATION
= Theoritical way to reduce Contamination?
Reduction Reactions at the Cathode
Reduction of H+: 2 H+ + 2 e- → H2 (Predominant)
Reduction of SO42-: SO H+ + 6e- → S + 4H2O
Does the cathodic overpotential provoked by a too high voltage an increased sulfur generation?
Sample A, 20 Volts:
9.18g removed
51 hours EP
Sample B, 5 Volts:
9.11g removed
115 hours EP
Assumed sulfur contamination
+ additional undesirable reactions???
18 janvier 2019
- F. Eozénou, T. Saeki FJPPL A_RD_05

30. XPS ANALYSIS AT SACLAY ON CONTAMINATED SAMPLE
Additional parasitic reduction likely to happen in HF depleted EP mixture
18 janvier 2019
- F. Eozénou, T. Saeki FJPPL A_RD_05

31. KEK-SACLAY EXCHANGE PROGRAM ON SAMPLES
4 samples electro-polished at Saclay and sent to KEK for surface analysis
High Voltage in Fresh EP Mixture
High Voltage in Aged EP Mixture
Low Voltage in Fresh EP Mixture
Low Voltage in Aged EP Mixture
A dedicated transportation box has been designed at KEK to keep the sample under inert gas atmosphere
18 janvier 2019
- F. Eozénou, T. Saeki FJPPL A_RD_05

32. TRANSPORTATION BOX (KEK DESIGN)
18 janvier 2019
- F. Eozénou, T. Saeki FJPPL A_RD_05

33. XPS ANALYSIS AT KEK (1) 18 janvier 2019
- F. Eozénou, T. Saeki FJPPL A_RD_05

34. Numerous components are found at the sample surface
XPS ANALYSIS AT KEK (2)
Numerous components are found at the sample surface
18 janvier 2019
- F. Eozénou, T. Saeki FJPPL A_RD_05

35. KEK SACLAY Zn O: 58% O: 51% N S, F: + S,F: - FIRST CONCLUSIONS
Differences are observed between Saclay and KEK samples
KEK
SACLAY Zn
O: 58%
O: 51% N
S, F: +
S,F: -
Sample analysis must be pursued for better understanding of the results
18 janvier 2019
- F. Eozénou, T. Saeki FJPPL A_RD_05

36. CONTINUED EXPERIMENTS
18 janvier 2019
- F. Eozénou, T. Saeki FJPPL A_RD_05

37. HISTORY OF 1DE1 SINGLE-CELL CAVITY
CEA/Saclay
KEK/STF
Eacc=40MV/m in VT on 28 Oct. 2008
21 Jul. 2009
Failure of sponge-wipe on 12 Aug. 2009
HF rinse, H2SO4 rinse to remove Al at scratch.
Eacc~25 MV/m limited by field-emission in VT on 14 Nov. 2009
17 Sept. 2009
3 Dec. 2009
Scratch was removed by
Local-grinding + EP(50um) + HPR on 8 Jan. 2010
VT is scheduled on 17 Feb. 2010
Jan. 2010
18 janvier 2019
- F. Eozénou, T. Saeki FJPPL A_RD_05

38. Cavity exchange program will be pursued.
OUTLOOK FOR 1DE1 CAVITY
Cavity exchange program will be pursued.
(1) send it back to Saclay
(2) confirm no FE by VT, sent back to KEK
(3) sponge-wipe to prove no-harmful.
(4) send it back to Saclay
(5) confirm no effect by VT
18 janvier 2019
- F. Eozénou, T. Saeki FJPPL A_RD_05

39. COMPLEMENTARY TESTS WITH LOCAL GRINDING
C1-21 Cavity
Goal: Cavity limited by early hard quench (25MV/m).
Recovery after local grinding?
Test with T-mapping (Saclay)
Printing of the surface (Saclay)
Local grinding of the surface + EP (KEK): tbc
RF test (Saclay)
18 janvier 2019
- F. Eozénou, T. Saeki FJPPL A_RD_05

40. NEW TEST WITH SPONGE-CLEANING
1AC3 Cavity
This cavity is a pristine one.
It will be EP’ed in “undesirable” conditions to evaluate efficiency of sponge-cleaning recipe.
Complementary EP (KEK)
RF test (Saclay)
EP with aged acid mixture and high voltage (Saclay)
RF test (Saclay). F.E expected
Sponge cleaning recipe (KEK)
18 janvier 2019
- F. Eozénou, T. Saeki FJPPL A_RD_05

41. Thank You for your Attention
18 janvier 2019
- F. Eozénou, T. Saeki FJPPL A_RD_05