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A RD 05: SURFACE PREPARATION STUDIES FOR SUPERCONDUCTIVE CAVITIES

A RD 05: SURFACE PREPARATION STUDIES FOR SUPERCONDUCTIVE CAVITIES. F. Eozénou , T. Saeki. CONTEXT. PARTICIPANTS. Visit Saeki San & Yamanaka San @ Saclay in March 2012. SURFACE TREATMENTS FOR LARGE SCALE CAVITY PRODUCTION. International Linear Collider

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A RD 05: SURFACE PREPARATION STUDIES FOR SUPERCONDUCTIVE CAVITIES

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  1. A RD 05: SURFACE PREPARATION STUDIES FOR SUPERCONDUCTIVE CAVITIES F. Eozénou, T. Saeki - F. Eozenou / T. Saeki - A_RD_05

  2. CONTEXT - F. Eozenou / T. Saeki - A_RD_05

  3. PARTICIPANTS VisitSaeki San & Yamanaka San @ Saclay in March 2012 - F. Eozenou / T. Saeki - A_RD_05

  4. SURFACE TREATMENTS FOR LARGE SCALE CAVITY PRODUCTION International LinearCollider ~16000 Superconductive Niobium cavities > 31.5 MV/m Improvement of the preparation of the SC Nb cavities • Cleaning of the surface • Reparation of defects • Increase in the reprocubility of the process • Costreduction • Industrialization • Cavitytratment/exchange program • Sampletreatments/analysis - F. Eozenou / T. Saeki - A_RD_05

  5. EXAMPLES OF CONTRIBUTION WITHIN TYL - F. Eozenou / T. Saeki - A_RD_05

  6. LOCAL GRINDING AT KEK Head : Diamond seat Motor (3000 rpm) CCDcamera＋LED Scratches on iris After grinding Grinding machine - F. Eozenou / T. Saeki - A_RD_05

  7. IMPROVEMENT AFTER GRINDING OF DAMAGED CAVITY Test aftergrinding and EP RF test of damaged 1Cell grinding Recovery of the cavityafter local grinding of the defectsatiris. - F. Eozenou / T. Saeki - A_RD_05

  8. SET-UP FOR SPONGE WIPING ON SINGLE-CELL UPW + detergent outlet Sponge mechanics Insertion PE sponge UPW + detergent inlet Poly-Ethylene (PE) sponge wipe handle Sponge Expansion and Wipe by rotation - F. Eozenou / T. Saeki - A_RD_05

  9. RESULTS ACHIEVED WITH SINGLE-CELL • Test with a good cavity (Eacc>35 MV/m, no FE) • Spongewipeat KEK • VT at Saclay • The performance of the cavityismaintained • The process do not deteriorate performance • Tests in challenging conditions (FE limitedcavity) • No improvementachieved • But suspiciouscleaningsequence • Experimentwillberepeated - F. Eozenou / T. Saeki - A_RD_05

  10. Fluid velocity [HF] at 4 000 s [HF] at 20 000 s MODELLING OF ELECTRO-POLISHING (Saclay) Field flatness degradation experimentally observed at KEK after electropolishing, How can modelling help us understand (and solve) the problem? Velocity m/s HF mol/m3 TESLA Cavities • Good electropolishing of central cell #5 • Electro-polishing will depend on the cell location for others →Electropolishingneeds to be improved in the other cells - F. Eozenou / T. Saeki - A_RD_05

  11. SURFACE CONTAMINATION ANALYSIS OF SAMPLES • SamplesEP’edat KEK & Saclay • Analysisat KEK • Same contaminants found (S, F, C) • More sulfur @ KEK • Influence of anode-cathode distance? • → Experiments to becontinued Surface Analyses (XPS) Surface Analyses (Auger/AES) Surface Analyses (SIMS) - F. Eozenou / T. Saeki - A_RD_05

  12. NEW EQUIPMENTS, NEW CHALLENGES - F. Eozenou / T. Saeki - A_RD_05

  13. VERTICAL EP (VEP) AT CEA SACLAY - F. Eozenou / T. Saeki - A_RD_05

  14. 3 cm EVOLUTION OF EP @ CEA SACLAY 2004: Experiments on flat samples: 2006: Operation of 1Cell Horizontal EP set-up 2011: Operation of Vertical EP Set-up - F. Eozenou / T. Saeki - A_RD_05

  15. EVOLUTION OF THE VEP SET-UP September 2011: Commissioning, Tests with water October 2011: Connections to exhausts, tests withacid in november January 2012: Area closed. Final configuration. - F. Eozenou / T. Saeki - A_RD_05

  16. HORIZONTAL VS VERTICAL • Pros: • Good evacuation of gases (cavityhalffilled) • Demonstratedefficiency • Large range of parameters • Pros: • Simple process • Lowfloor surface • Improvedsafety • Higherremoval rate • Cons: • Complicatedprocess • Rotary seals • Switching of the cavity • Lowremoval rate • Cons: • Sensitive to fluiddynamics • Properparameters to bedetermined… …Voltage and fluidvelocity - F. Eozenou / T. Saeki - A_RD_05

  17. Fluid velocity [HF] at 4 000 s [HF] at 20 000 s VERTICAL CONFIGURATION AND MODELLING Z r Cathode • Modelling of horizontal EP: • Difficult: no symmetry • Hints for non uniformpolishing Fz Configuration simpler in VEP case: Symmetryaccording to z-axis → 2D axisymmetry model - F. Eozenou / T. Saeki - A_RD_05

  18. EXAMPLE OF MODELLING Flow profile from the cathode to the cavity: Fluidvelocitym/s Vs x Fluidvelocitym/s Electrolyte velocity: m/s • Modelling (COMSOL) withrod cathode • Area close to the cellpoorlysweptwith SPL cavities • Needsimprovement - F. Eozenou / T. Saeki - A_RD_05

  19. Modified Cathode Shape (SPL cavity) Fluidvelocitym/s Vs x Fluidvelocitym/s Fluidvelocity m/s Example of fluidmodellingwith alternative shape • VEP WITH CIRCULATING ACID SHOULD NOT BE CELL DEPENDENT • SHAPED CATHODE MAKE IT POSSIBLE TO IMPROVE THE FLOW - F. Eozenou / T. Saeki - A_RD_05

  20. FIRST VEP WITH 1Cell Parameters for 1st VEP sequence: - 3 hours VEP - Shaped and masked cathode - 8 L/min acidflowrate, Nitrogenblowing - 20 V - Temperature < 26°C • Benefitsfrom VEP: operatorfriendly! • No flawobservedduring the first VEP sequence • Easypreparation of the cavity (time saved + security) • More efficient rinsingprocedures • Verystable process • → Adapted to industry - F. Eozenou / T. Saeki - A_RD_05

  21. RESULTS AFTER EPV A 20V • Bright Surface • Brighter on top half-cell • … but bubble traces • → 20 V = Oxygengeneration Acid flow (8L/min) not sufficient to stir the gas +Ar Baking 3hx145°C - F. Eozenou / T. Saeki - A_RD_05

  22. EPV WITH LOWER VOLTAGE (12V) 1Cell VerticallyEP’edat 12V. Improvement of the surface. • No obviousbubble trace at the uppercell • Brightening of the surface • Promising Voltage • → Waiting for the RF Test of the cavity - F. Eozenou / T. Saeki - A_RD_05

  23. NEW CAVITY FABRICATION FACILITY AT KEK - F. Eozenou / T. Saeki - A_RD_05

  24. Introduction of KEK activities • The fabrication-cost reduction of superconducting cavity is not enough for future project like ILC. We have constructed a new superconducting Cavity Fabrication Facility (CFF) at KEK for the study of cost-effective mass-production of cavity. • All the necessary equipment for the cavity fabrication were installed in the CFF at KEK. • We have fabricated 9-cell cavity KEK-00 (without HOM) in CFF. The fabrication process of KEK-00 and the vertical test result of KEK-00 will be shown. • Future plan of CFF will shown as well as the plan of FJPPL collaboration between Saclay and KEK.

  25. Main Equipments of Cavity Fabrication Facility EBW room Installation of EBW machine started from April 2011. Chemical Polishing room Measuring system for half cell shape (Under developing) Press machine (servo control) Inspection equipment for Nb surface Vertical lathe 25

  26. 4 – Dumbbell, 8 – Dumbbell EBW at Job-shop (June 2011 – July 2011) Beam 30 June 2011 6 July 2011 Beam 8 July 2011

  27. Fabrication of KEK-00 Cavity (w/o HOM) Beam-pipe(Nb) End-cells (Nb) End-Plates (Ti) + Nb ring End-Plates (Ti) + Nb ring Beam-pipe (Nb) Flanges (Nb-Ti alloy) Input-port pipe (Nb) Center cells (Nb) / EBW at job shop Dumb-bell (Nb)

  28. Final EBW at Equator of End-Cell at Job Shop 1 Dec. 2011 Cell#1 Voltage Beam Current Position of hole Failure in the EBW at the equator of end-cell (cell#1)/ 120 kV, 30 – 29 mA.

  29. Repair of 9-cell cavity KEK-00 by EBW The setup of EBW of KEK-00 to repair the hole of cell#1. 30 Jan. 2012 (Mon.) EBW bead EBW bead EBW Small Nb piece was made and it was set into the hole. EBW with 120kV, 20mA, and 5 mm/s.

  30. Observation of repaired part and local grinding A picture of repaired part: inner surface of cell#1-equator, theta=237 deg. (1st Feb. 2012) Observation by Kyoto camera EBW bead EBW bead Area of EBW for repairing the hole of cell#1 Local grinding was done for the inner surface of the repaired part of cell#1 by hand in order to make a smooth surface. (3 Feb. 2012).

  31. Surface treatment of 9-cell cavity (KEK-00) Bulk EP (100 um), Degreasing (50 0C, 30 min), HPR (1.5 h), Annealing(4 h, 750 0C), and final EP (20 um). HPR (7 hours) Brushing Brushing of beam-pipe and HOM antenna. Degreasing with detergent (FM-20 2%) in hot bath (500C, 30 min).

  32. Vertical Test Result of 9-cell cavity w/o HOM (KEK-00) Eacc = 29 MV/m Q0 = 9 x 10^9 Cell#1 (repaired cell) reached to 42.7 MV/m in the 6pi/9 mode. Limitation in the pi mode might be quench at cell#8, because the T-mapping sensor detected higher temperature in cell#8 in coincidence with the quench at 29 MV/m.

  33. Future Plan of Cavity Fabrication Facility (CFF) April Activities FY 2011 FY2012 April Surface preparation and VT 9-cell cavity: KEK-00without HOM Fabrication Surface preparation and VT Machining of all parts by KEK 9-cell cavity: KEK-01 with HOM EBW of all seams at CFF(KEK) 9-cell cavities: KEK-02 with HOM Study for the high-pressure code application Fabrication Single-cell cavityfor FJPPL collaboration This cavity will be used for the vertical EP test at Saclay. Fabrication

  34. Summary of KEK activities • All equipment (press machine, CP room, EBW machine, etc) were installed in Cavity Fabrication Facility (CFF). • 9-cell cavity KEK-00 (w/o HOM) was fabricated. Center cells were EBW’ed at job shop and end-groups were EBW’ed in CFF(KEK). • Final EBW of KEK-00 cavity at the equator of end-cell was failed, but it was repaired. After surface preparation at KEK, KEK-00 reached to Eacc = 29 MVm in vertical test. • 9-cell cavity KEK-01 and -02 (w/ HOM) will be fabricated where all seams will be EBW’ed at CFF(KEK) in FY2012. • We will fabricate a single-cell cavity in CFF at KEK. This cavity will be used for the study of vertical EP at Saclay in the frame-work of FJPPL collaboration.

  35. OBJECTIVE FOR FY 2012 - F. Eozenou / T. Saeki - A_RD_05

  36. Plan of Collaboration with Single-Cell Cavity Fabrication of single-cell cavity at CFF(KEK). Vertical EP of the cavity and vertical test at Saclay. Fabrication of a single-cell cavity at CFF(KEK). This cavity will be used for the study of vertical EP at Saclay in the frame-work of FJPPL collaboration.

  37. ON-GOING SAMPLES EXPERIMENTS EP @ KEK. Rotating Nb samples. EP @ Saclay. static Nb samples. • Same contaminants observed • Quantitiesdiffer (Sulfur) • More sulfurfoundat iris at KEK • Electrodes’ configuration incriminated Samplesmeasurements on cavities @ KEK. • 4 sampleswillbeEP’ed, 4 different anode-cathode distance (Saclay) • Packing in Cleanroom in dedicated box • Analysis of samples (KEK) - F. Eozenou / T. Saeki - A_RD_05

  38. COMPARISON HEP/VEP • 2 advancedequipments • Efficiency of HEP demonstrated • Experiencenecessary for VEP • Unique opportunity for fruitfulcomparison • KEK HEP’edcavityshipped to Saclay • VEP @ Saclay • VT @ Saclay • Comparison HEP @ KEK VEP @ Saclay - F. Eozenou / T. Saeki - A_RD_05

  39. ON-GOING GRIDING/WIPING EXPERIMENTS • KEK Grindermakesit possible to treatequator and iris • New headunderdevelopment to reachany part of a cell • Saclay Cavitywithpits sent to KEK • Local grinding of the defects • Cavityshipped back to Saclay for VT • Additionalsponge-wiping of contaminatedcavity KEK grinding system Saclay cavitywithpits Saclay cavitywith FE KEK wiping system - F. Eozenou / T. Saeki - A_RD_05

  40. THANK YOU FOR YOUR ATTENTION - F. Eozenou / T. Saeki - A_RD_05

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