FOR SUPERCONDUCTIVE CAVITIES A RD 05: SURFACE PREPARATION STUDIES FOR SUPERCONDUCTIVE CAVITIES F. Eozénou, T. Saeki 18 janvier 2019 - F. Eozénou, T. Saeki - FJPPL 2010 A_RD_05

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 2010 A_RD_05

OUTLINE CONTEXT RESULTS ACHIEVED ON SINGLE-CELL CAVITY SURFACE ANALYSIS ON SAMPLES CONTINUED EXPERIMENTS 18 janvier 2019 - F. Eozénou, T. Saeki - FJPPL 2010 A_RD_05

CONTEXT 18 janvier 2019 - F. Eozénou, T. Saeki - FJPPL 2010 A_RD_05

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 2010 A_RD_05

+ 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 2010 A_RD_05

DESIGN OF A VERTICAL EP FACILITY AT SACLAY To be used in: 18 janvier 2019 - F. Eozénou, T. Saeki - FJPPL 2010 A_RD_05

SET-UP AND PREPARATION AREA 18 janvier 2019 - F. Eozénou, T. Saeki - FJPPL 2010 A_RD_05

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 2010 A_RD_05 9

RESULTS ACHIEVED WITHIN THE COLLABORATION SURFACE TRATMENTS ON 1-CELL CAVITY 18 janvier 2019 - F. Eozénou, T. Saeki - FJPPL 2010 A_RD_05

CHEMICAL REACTIONS DURING EP: SULFUR IS GENERATED - SO42- S Al 3+ H+ Nb5+ + 18 janvier 2019 - F. Eozénou, T. Saeki - FJPPL 2010 A_RD_05

FIELD EMISSION IS STILL A MAJOR ISSUE → Necessary to improve contaminants removal on cavities 18 janvier 2019 - F. Eozénou, T. Saeki - FJPPL 2010 A_RD_05

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 2010 A_RD_05 13

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 2010 A_RD_05

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 2010 A_RD_05 15

SPONGE-WIPE TOOL SCRATCHED THE IRIS Mistake occured during 1DE1 Sponge-Wipe Cleaning 18 janvier 2019 - F. Eozénou, T. Saeki - FJPPL 2010 A_RD_05 16

DETERIORATION OF THE SURFACE Iris EBW seam. Scratched part. + Aluminum traces BP side Cell side 18 janvier 2019 - F. Eozénou, T. Saeki - FJPPL 2010 A_RD_05

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 2010 A_RD_05 18

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 2010 A_RD_05 19

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 2010 A_RD_05

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 2010 A_RD_05 21

(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 2010 A_RD_05

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 2010 A_RD_05

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 2010 A_RD_05

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 2010 A_RD_05 25

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 2010 A_RD_05

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 2010 A_RD_05

SURFACE ANALYSIS ON SAMPLES 18 janvier 2019 - F. Eozénou, T. Saeki - FJPPL 2010 A_RD_05

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-: SO42- + 8H+ + 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 2010 A_RD_05

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 2010 A_RD_05

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 2010 A_RD_05

TRANSPORTATION BOX (KEK DESIGN) 18 janvier 2019 - F. Eozénou, T. Saeki - FJPPL 2010 A_RD_05

XPS ANALYSIS AT KEK (1) 18 janvier 2019 - F. Eozénou, T. Saeki - FJPPL 2010 A_RD_05

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 2010 A_RD_05

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 2010 A_RD_05

CONTINUED EXPERIMENTS 18 janvier 2019 - F. Eozénou, T. Saeki - FJPPL 2010 A_RD_05

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 2010 A_RD_05

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 2010 A_RD_05

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 2010 A_RD_05

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 2010 A_RD_05

Thank You for your Attention 18 janvier 2019 - F. Eozénou, T. Saeki - FJPPL 2010 A_RD_05