Status of RFCC-Module Development

1. Status of RFCC-Module Development Derun Li Center for Beam Physics Lawrence Berkeley National Laboratory MICE Collaboration Meeting at INFN-LNF, Frascati, ITALY June 26 ~ 29, 2005

2. The RFCC-Module in MICE Coupling Coils Power couplers Eight 201 MHz cavities Status of the RFCC-Module Derun Li

3. Overview Status and development • Progress on the 201 MHz Prototype Cavity (MUCOOL/MICE) • Current level of completion • RF couplers • Curved Be windows • Other accessories • High power test at MTA, FNAL (development) • Coupling coil magnet (M. Green) • Forces and quench protections • Integration to AFC module (W. Lau/S. Virostek) Status of the RFCC-Module Derun Li

4. Status of the cavity • In collaboration with J-Lab, U. of Mississippi, Oxford University • Cavity fabrication: e-beam welding, EP and cleaning • Power couplers: assembly and high power tests at SNS • Vacuum assembly, …, shipping • Curved Be windows • In MTA, FNAL • Preparation for accepting the cavity • Cleaning room purchased and will allow us for in situ assembly of • Couplers • Window replacement • Inspection of cavity • Low power measurement: frequency and coupling • High power test at MTA, FNAL • Plan being developed Status of the RFCC-Module Derun Li

5. Cavity: Current Level of Completion • E-beam welding • Ports • Water cooling lines • Couplers assembled first time • (mid-April-2005) • First low power measurement • frequency ~ 199.5 MHz • coupling ~ 5 (max) • Q ~ 5000 Status of the RFCC-Module Derun Li

6. Cavity Progress (Apr-2005) Ready for mechanical cleaning and EP Couplers ready for conditioning Status of the RFCC-Module Derun Li

7. U-Shape Electrode Cavity Progress: EP (June-05) After 1st EP run (Early June 2005) Status of the RFCC-Module Derun Li

8. Cavity Status • EP setup works, but the first EF was not satisfactory • ~ 13 lbs of copper removed • 40.6 in3 removed (0.32 lb/in3) • Cavity interior surface area: ~ 4700 in2 • Average thickness removed: 8.6 mils (219 microns) • Amounts to 3.4% to 5.0% of the initial thickness • Green crystals developed due to the saturated solution • Un-even surface and hard to clean away • Mechanical cleaning again (over last weekend) • 2nd EP under way • New solution • New chiller to cool the electrode • More cautiously • Expect the cavity at MTA next month (July 2005) Status of the RFCC-Module Derun Li

9. Cavity Development in UK • Recent development in UK (K. Long, Graham Gosling) • Cavity fabrication of the RFCC-module • 1st meeting in June 15, 2005 • Exchange ideas and information for cavity fabrication and future development • More meetings in the future (?) Tuner and mounting ideas Status of the RFCC-Module Derun Li

10. Load RF Power Two couplers RF Couplers Two Couplers (ready!) • Critical coupling • Ceramic windows are integrated in the couplers • Design and built at LBNL • Conditioning started using 805 MHz RF power at the SNS • Good vacuum ~ low 10-8 T • Achieved 600 kW in TW mode (matched load) • Achieved 10 kW average power (~ 9 kW average for nominal NF parameters) • Achieved 2.4 MW peak power in SW mode (at variable short positions) • Ceramic windows work fine during two weeks of the RF conditioning Status of the RFCC-Module Derun Li

11. 420 mm Curved Be Windows • Succeeded in two curved Be windows so far for the 201-MHz cavity • The windows are • 0.38 mm thick, 420 mm diameter • RF heating ~100 watts per window with ∆T~ 55 degrees for nominal Study-II parameters • Window is formed by applying a die at elevated temperature • Copper frame is brazed to Be window • Be windows will be Ti-N coated shortly • Asymmetry RF heating • Curved-in window experiences 40% more RF heating than the one that curved-out • Small changes respect to overall RF power dissipation on the cavity • FEA (in collaboration with Oxford group) indicates the window should still work Status of the RFCC-Module Derun Li

12. Support Stand/Manual Tuner • Manual tuner consists of thick aluminum plates connected by adjustable struts • Tuner allows cavity frequency adjustment while providing support for interior vacuum load • Parts for tuner fabricated in U. of Miss. Shop, and now at J-Lab • Support stand attaches to one tuner plate and allows cavity to be placed adjacent to MTA magnet • Support design and construction have completed, now at J-Lab MTA (Lab G) Magnet Status of the RFCC-Module Derun Li

13. The Cavity & its accessories Need careful planning and coordination! Status of the RFCC-Module Derun Li

14. High Power Test at MTA Plans under way • Coordination among LBNL, J-Lab, ANL and FNAL • Diagnostics (identified in last MICE meeting in Berkeley) • Preliminary plan so far • In situ assembly of couplers, vacuum pump and gauges • Power splitter (Tee) at 6” coaxial transmission lines • Transitions to 4” coaxial lines with elbows to the couplers • Ti-N coated flat copper windows • In situ baking (choices: hot N2 or water) • Low power RF measurement of frequency and Q • Coupling balance and adjustment • Calibration of RF probes • Conditioning without magnetic field first • Suggestions are very welcome Status of the RFCC-Module Derun Li

15. Summary • Cavity fabrication is nearly complete with unexpected delays • EP + pressured water rinsing • Packing and shipping to MTA, FNAL • Two couplers have been high power processed and ready for final assembly at MTA • Significant progress on curved Be window • High power test plans being developed • Recent development of RFCC-module in UK • MICE tuner ideas can be tested at RM and low power • Integration of RF coupler to MICE RFCC-module • Future cavity fabrication Status of the RFCC-Module Derun Li