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MICE RF Cavities and RFCC Module Update

Derun Li Lawrence Berkeley National Laboratory. MICE RF Cavities and RFCC Module Update. MICE RF Workshop Daresbury Laboratory, UK April 17, 2012. MICE Cooling Channel.

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MICE RF Cavities and RFCC Module Update

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  1. Derun Li Lawrence Berkeley National Laboratory MICE RF Cavities and RFCC Module Update MICE RF Workshop Daresbury Laboratory, UK April 17, 2012

  2. MICE Cooling Channel Two RFCC modules, four 201-MHz cavities per module, four ports per cavity: two of them for RF couplers, one for vacuum pump and one for RF probe; Two beryllium windows per cavity.

  3. RFCC Module Six tuner arms & actuators per cavity, and cavity is supported by strut system.

  4. Current Status of RFCC Module • RF Cavities and single cavity vessel: • All 11 beryllium windows received at LBNL (1st RFCC module) • Ten ceramic RF windows received • Six tuner flexures are being fabricated at Fermilab • Components for 6 actuators are being fabricated • RF coupler design has been modified to eliminate the gap between the outer coax and the RF loop • Fabrication of fixturing for the electropolishing is nearly complete • Mechanical smoothing of the cavity inside surface before EP • Single cavity vacuum vessel, fabricated at Keller Technology in Buffalo New York, is complete and is at Fermilab now.

  5. Beryllium Windows • Eleven beryllium windows have been fabricated so far: • Curved thin (0.38-mm thick) window with TiN-coating on both sides • Received two new beryllium windows recently, these two windows have been fabricated by MaterionElectrofusion (fomer Brush-Wellman) to replace the windows rejected due to excess distortion with improved brazing design/technique: no distortion is observed.

  6. RF Cavity Frequency Tuner Components • Dual – action actuator • Flexure • tuner arm • RF cavity Tuning range:  230 kHz Cross-section view

  7. Cavity Frequency Tuner Flexure • Finished tuner arm • Jan. 25-26, 2012 in Fermilab • Six full size tuner flexures are being fabricated at Fermilab

  8. Actuator Component Fabrication Upper piston Center plate Lower piston Lower support • Component for six actuators are currently being fabricated by a local vendor • The actuators will be assembled at LBNL

  9. RF power (loop) coupler • RF power (loop) coupler design has been modified to eliminate the gap between the loop and the outer coax tube

  10. RF Power (loop) Coupler (old) Cross-section view MTA RF coupler Old MICE design • Testing/experience of the prototype cavity at MTA: sparking at the coupler • The coupler design has been changed slightly to increase the gap spacing • The sparking region can be TiN coated if necessary (plan to be tested at MTA using the prototype cavity) • Adding diagnostics: arc detector at the coupler region.

  11. RF power (loop) coupler Cross-section view Cross-section view • Modified MICE RF power coupler design is complete, drawing package has been delivered to FNAL, and ready for fabrication • Fabrication of the couplers should start soon

  12. Cavity Measurements Cavity physical measurement Cavity frequency measurement • Physical measurements for the six remaining cavities expected to take approximately 1-1/2 weeks (60 hours) • RF measurements and tuning to a center frequency after the EP of all ten cavities (two spares) at LBNL.

  13. Cavity Electropolish at LBNL Cavity section view EP rotation fixture at LBNL • The inner surface of each cavity will be mechanically smoothed and then electropolished at LBNLusing the similar techniques developed at JLab for the prototype cavity • Fabrication ofEP fixturing is complete and electropolishing will start in soon after ES & H approval • Electropolishing process will take approximately 1- 2 days for each cavity or 4 weeks to complete all 10 cavities

  14. Cavity Electropolish at LBNL (cont’d) Cavity section view New fixture for EP exhaustfabricated, testing and meeting with ES&H personnel scheduled.

  15. Ongoing Simulations of MICE RF Cavity • Study of external magnetic field on MICE RF cavity and coupler (Dr. TianhuanLuo) • 3D simulations (from CAD model) using SLAC’s Omega-3P code: f = 201.866 MHz • MP simulations, and RF breakdown studies with an external magnetic field

  16. Single Cavity Vacuum Vessel Vacuum vessel stand Vacuum vessel Vacuum vessel cover plate Single Cavity Vacuum Vessel and MuCool Coupling Coil Magnet Fabrication of the single cavity vacuum vessel is complete at Keller Technology in Buffalo New York

  17. RFCC Future Work • RFCC Vacuum Vessel: • Vessel design is complete but needs to be updated to incorporate changes to the interface with the new coupling coil cryostat design • Fixturing for the assembly process needs to be finalized and drawings for fabrication generated • RFCC Module: • Finalize fixturing for module assembly and shipping • for aligning the frequency tuners onto cavities • for inserting the cavities into vacuum vessel • shipping skid/tilt fixturing for shipping RFCC to RAL

  18. RFCC Future Work (cont’d) • RF control/analysis: this workshop • Diagnostics/control/analysis/interfaces • LLRF control (amplitude/phase) and correlations with detectors • Timing signal from detector, and calibration & synchronization with RF • DL group should take the leadership and ownership • LBNL group will assist under MAP support • Understanding the engineering approach and scope of work • Development of future plan and define responsibilities of each group.

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