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DESIGN OF A NEW SET-UP AT CEA SACLAY FOR VERTICAL ELECTRO-POLISHING (VEP)

DESIGN OF A NEW SET-UP AT CEA SACLAY FOR VERTICAL ELECTRO-POLISHING (VEP). F. Eozénou. OUTLINE. CONTEXT TECHNICAL CHOICES FOR VERTICAL EP SET-UP CHALLENGES AND R&D RELATED TASKS. CONTEXT. HIGH PERFORMANCE SURFACE TREATMENT REQUIRED FOR DIFFERENT TYPES OF CAVITIES. ILC Hi-Grade Program

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DESIGN OF A NEW SET-UP AT CEA SACLAY FOR VERTICAL ELECTRO-POLISHING (VEP)

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  1. DESIGN OF A NEW SET-UP AT CEA SACLAY FOR VERTICAL ELECTRO-POLISHING (VEP) F. Eozénou - F. Eozénou - TTC Meeting WG4 Fermilab

  2. OUTLINE • CONTEXT • TECHNICAL CHOICES FOR VERTICAL EP SET-UP • CHALLENGES AND R&D RELATED TASKS - F. Eozénou - TTC Meeting WG4 Fermilab

  3. CONTEXT - F. Eozénou - TTC Meeting WG4 Fermilab

  4. HIGH PERFORMANCE SURFACE TREATMENT REQUIRED FOR DIFFERENT TYPES OF CAVITIES • ILC Hi-Grade Program 8 Tesla Shape cavities to be treated (final step) and tested at Saclay: Final VEP + Rinsing + Test • Surface treatment for large proton cavity Ø382mm L>1430mm 1,76 m288L (Tesla: Ø=211mm L=1283mm) β = 1 cavity Eacc = 25 MV/m Need for an efficient surface treatment→ Choice for Electro - Polishing + (optionnal) EP for β = 0.65 cavity Eacc = 19 MV/m - F. Eozénou - TTC Meeting WG4 Fermilab

  5. WHY VERTICAL EP? • EP PROMISING FOR HIGH GRADIENTS • HORIZONTAL EP NON SUITED FOR LARGE CAVITIES • SIMPLER PROCESS • EFFICIENCY OF VERTICAL EP DEMONSTRATED FOR TESLA-SHAPE 9CELL CAVITIES (CORNELL UNIVERSITY). + see Presentation by G. Hoffstaetter and Z. Conway VEP Parameters must be considered carrefully… • ILC-CAVITY EP PARAMETERS NON SUITED TO SPL CAVITIES? • CAVITY FULL OF ACID (Vs HALF-FILLED for horizontal EP) • SUPERFICY OF THE CAVITY x2 • ~15 kW TO DISSIPATE? (17V) - F. Eozénou - TTC Meeting WG4 Fermilab

  6. BENEFITS FROM PREVIOUS CARE SRF PROGRAM ALTERNATIVE EP PARAMETERS TESTED: WP 5.1 EP ON 1-CELLS • EP @ LOWER VOLTAGE (5V) INVESTIGATED • NO HEATING OF THE BATH • GOOD RF PERFORMANCE • LESS IMPURITIES Pristine 1C21 after 150 µm EP 5V Vs 17V on 1DE1 COMPARABLE RESULTS WITH 5V ELECTRO-POLISHING - F. Eozénou - TTC Meeting WG4 Fermilab

  7. + LESS IMPURITIES AT LOWER VOLTAGE Presented at TTC 2008 & SRF 2009 Does a cathodic overpotential leads to an increased sulfur generation? →Two Niobium samples electro-polished at 5V and 20V for a similar heavy removal with 1-9-1 (HF-H2SO4-H2O) Mixture Sample A, 20 Volts: 9.18g removed Sample B, 5 Volts: 9.11g removed Visible contamination for Sample A → We have compared impurities found in electrolytes A & B ~ X2 Impurities in A Mixture - F. Eozénou - TTC Meeting WG4 Fermilab

  8. TECHNICAL CHOICES FOR VERTICAL EP SET-UP - F. Eozénou - TTC Meeting WG4 Fermilab

  9. Circulating Acid Acid flowrate: 0-40 L/min Acid cooled thanks to heat exchanger inserted in the acid tank Nearly all piping in PFA Hydrogen diluted in Nitrogen flow Will for set-up with two storage acid tanks Mix VEP and BCP Mix Chemical treatment and rinsing recipe Use different electrolytes composition Cathode introduced in horizontal configuration → need for a dedicated bench Automated Process Data Monitoring (temperature, intensity, voltage, flowrate) Power Supply: 0-20V 2250A (tbc) DETAILS OF THE SET-UP - F. Eozénou - TTC Meeting WG4 Fermilab

  10. Gas Scrubber T: Temperature Sensor Qg/Qa: flow meter acid/gas Qg Nitrogen for Cavity T Tair Qg Qg Hydrogen Sensor cathode 20V, 2kA Nitrogen for tank Rinsing Cavity Filling for tank Qa Tank Acid2 Tank Acid1 T T Rinsing Tank filters filters Water for cooling - F. Eozénou - TTC Meeting WG4 Fermilab

  11. 3D - VIEW - F. Eozénou - TTC Meeting WG4 Fermilab

  12. Engineering subcontracted « Auxitec Ingénierie » chosen after call for tender PID, materials, specifications, suppliers, 3D-drawings Evaluation of the cost for the set-up (+/- 20%) Study has been made for both 1-tank and 2-tank configurations DETAILS CONCERNING THE DESIGN PHASE 2d Call for tender under preparation… … for the construction of the machine FINAL CONFIGURATION WILL BE CHOSEN AFTER RECEPTION OF THE OFFERS FOR THE CALL FOR TENDER BUILDING IN TWO STAGES? - F. Eozénou - TTC Meeting WG4 Fermilab

  13. DETAILED PID Most valves automated, sensors (T, H, acid level) integrated in safety procedures - F. Eozénou - TTC Meeting WG4 Fermilab

  14. DRAWINGS OF ACID STORAGE TANKS - F. Eozénou - TTC Meeting WG4 Fermilab

  15. VIEW OF THE SET-UP AND OF THE PREPARATION AREA Pneumatics Pneumatics Cooling system Power supply Cathode insertion Cooling system Pneumatics Cathode insertion Cathode insertion Pneumatics Power supply Power Supply Cooling system Cooling system - F. Eozénou - TTC Meeting WG4 Fermilab

  16. CHALLENGES AND R&D RELATED TASKS - F. Eozénou - TTC Meeting WG4 Fermilab

  17. FLUID DYNAMICS MODELLING WITH COMSOL • Makes it possible to combine matter flux (diffusion) and fluid dynamics Previous study (SRF 2007) → improvement by cathode shape modification Fluid Velocity Acid (HF) concentration Improved modelling by using 2D Axi-symmetry • Thermal modelling with CFDesign investigated at JLab (C. Reece et al., SRF 2009) - F. Eozénou - TTC Meeting WG4 Fermilab

  18. PARAMETERS TO BE INVESTIGATED • FLUID VELOCITY • TEMPERATURE • CHEMICALS CONCENTRATION • POTENTIAL DISTRIBUTION • DESIGN OF THE CATHODE • STUDY OF THE Nb REMOVAL (NEED TO SWITCH THE CAVITY?) • ROUGHNESS ACHIEVED • Etc. - F. Eozénou - TTC Meeting WG4 Fermilab

  19. THANK YOU FOR YOUR ATTENTION! - F. Eozénou - TTC Meeting WG4 Fermilab

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