5-Year RF R&D Plan

1. 5-Year RF R&D Plan Derun Li Lawrence Berkeley National Laboratory NFMCC and MCTF Phone Meeting Friday, September 18, 2009

2. Recommendations from MUTAC 2008 • Recommendations from MUTAC Review 2008 on RF programs • Pursue a more aggressive program at MTA, taking advantages of its unique facilities to do experiments that compliment the MICE program • In addition to 805 MHz experimental programs, we have been working on normal conducting 201-MHz cavity: • Gradient of ~ 16 MV/m in a few Tesla magnetic fields environment • MICE cavity fabrication progressing well; the cavity gradient is limited to 8 MV/m due to available RF power • No SC coupling coil magnet yet Derun Li - Lawrence Berkeley National Laboratory, Sep. 18, 2009

3. Recommendations from MUTAC 2009 Three recommendations on RF R&D and 5-year plan: • Provide a resource loaded RF R&D schedule, highlighting prioritized activities and any potential for expediting the down-selection process. • Define a minimum RF specification to expedite the RF down-selection. • Modify the employed QA processes to change the 201 MHz Be windows to ensure more appropriate protection of the RF surfaces. • MuCool prototype or MICE cavity? Derun Li - Lawrence Berkeley National Laboratory, Sep. 18, 2009

4. Responses to MUTAC 2009 • Down-selection (2) in MUTAC Recommendation 1. & 2. • Major challenges of RF cavity in cooling channels: • RF gradient limit: RF gradients degradation of normal conducting cavities in external magnetic fields • RF breakdown and surface damage associated with the external magnetic fields • RF R&D plan • Understand the RF breakdown problem in magnetic field • Physics models • Experimental programs • Is thisa show stopper ? • No ; different cooling channel? • Do we have (or presented to MUTAC) too many options? • No, pillbox-like closed (by Be windows) with different materials and coatings • Pressurized cavity Derun Li - Lawrence Berkeley National Laboratory, Sep. 18, 2009

5. Summary of R&D Plans • Continue experimental studies at 805-MHz • The 805-MHz pillbox cavity has been refurbished and should be ready soon for more button (new + old button configurations) tests for RF breakdown studies • High pressured cavity test at MTA (Muons, Inc. + FNAL): no SBIR Phase-II support, what’s next? • 201-MHz cavity program • RF cavities for MICE : progressing well • SC coupling coil for MuCool RF breakdown studies at MTA: • Collaboration with ICST of HIT, Harbin for design and fabrication, making progress slowly; • 3.15 M RMB funding approved by HIT, contract to be rewarded soon (hopefully) Derun Li - Lawrence Berkeley National Laboratory, Sep. 18, 2009

6. Summary of R&D Plans (cont’d) • RF breakdown studies • Magnetic insulation: • Box cavities at FNAL to study ExB effects; the cavity is almost ready. • Other options: • All beryllium cavity • ALD cavity: current work focus on SC RF cavity • Theoretical studies on RF breakdown, physics model to understand RF breakdown in magnetic fields, in collaboration with SLAC • BNL (R. Palmer)’s model • Be cavity • ANL (J. Norem)’s model • ALD cavity • SC RF cavity for acceleration Derun Li - Lawrence Berkeley National Laboratory, Sep. 18, 2009

7. Dielectric Loaded RF Cavity Motivation: • To fit pressurized cavities in HCC, size of cavity has to be reduced • Examples: • 800 MHz dielectric loaded cavity • Maximum RF cavity radius = 8 cm, (pillbox cavity: 14.3 cm) • Radius of effective electric field (95 % from peak) = 3 cm • 400 MHz dielectric loaded cavity • Maximum RF radius = 16 cm (pillbox cavity: 28.6 cm) • Radius of effective electric field = 6 cm Dielectric ring Derun Li - Lawrence Berkeley National Laboratory, Sep. 18, 2009

8. Responsibility for MICE (RFCC Module) August 29, 2009 SC coupling Coil Curved Be window Cavity Couplers Vacuum Pump 201-MHz cavity Derun Li - Lawrence Berkeley National Laboratory, Sep. 18, 2009

9. Summary • Muon Ionization Cooling Channel requires normal conducting RF cavity operating in a few Tesla magnetic field • Remains a challenge • 201-MHz RF cavity for MICE progressing well • The first five cavities expect to be delivered to LBNL in Nov. 2009 • Superconducting coupling coil contract to be awarded soon • Plans for RF breakdown studies • Vacuum cavity • 805-MHz button cavity and box cavity tests • 201-MHz cavity test to be resumed soon • Beryllium cavity design starts soon • ALD processed cavity to eliminate field emission • Dielectric loaded cavity • High pressured RF cavity tests Derun Li - Lawrence Berkeley National Laboratory, Sep. 18, 2009