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

MCTF 5-Year RF R&D Plan Page 2Derun Li - Lawrence Berkeley National Laboratory, Sep. 18, 2009 Recommendations from MUTAC 2008 Recommendations from MUTAC Review 2008 on RF programsRecommendations 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: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

MCTF 5-Year RF R&D Plan Page 3Derun Li - Lawrence Berkeley National Laboratory, Sep. 18, 2009 Recommendations from MUTAC 2009 Three recommendations on RF R&D and 5-year plan: 1.Provide a resource loaded RF R&D schedule, highlighting prioritized activities and any potential for expediting the down- selection process. 2.Define a minimum RF specification to expedite the RF down- selection. 3.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?

MCTF Responses to MUTAC 2009 Down-selection (2) in MUTAC Recommendation 1. & 2.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 fieldsRF gradient limit: RF gradients degradation of normal conducting cavities in external magnetic fields RF breakdown and surface damage associated with the external magnetic fieldsRF breakdown and surface damage associated with the external magnetic fields –RF R&D plan Understand the RF breakdown problem in magnetic fieldUnderstand the RF breakdown problem in magnetic field –Physics models –Experimental programs –Is this a show stopper ? No ; different cooling channel?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 coatingsNo, pillbox-like closed (by Be windows) with different materials and coatings Pressurized cavityPressurized cavity 5-Year RF R&D Plan Page 4Derun Li - Lawrence Berkeley National Laboratory, Sep. 18, 2009

MCTF 5-Year RF R&D Plan Page 5Derun Li - Lawrence Berkeley National Laboratory, Sep. 18, 2009 Summary of R&D Plans Continue experimental studies at 805-MHzContinue 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 program201-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)

MCTF 5-Year RF R&D Plan Page 6Derun Li - Lawrence Berkeley National Laboratory, Sep. 18, 2009 Summary of R&D Plans (cont’d) RF breakdown studiesRF breakdown studies —Magnetic insulation: –Box cavities at FNAL to study ExB effects; the cavity is almost ready. —Other options: All beryllium cavity All beryllium cavity ALD cavity: current work focus on SC RF 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 SLACTheoretical studies on RF breakdown, physics model to understand RF breakdown in magnetic fields, in collaboration with SLAC BNL (R. Palmer)’s modelBNL (R. Palmer)’s model Be cavityBe cavity ANL (J. Norem)’s modelANL (J. Norem)’s model ALD cavityALD cavity SC RF cavity for accelerationSC RF cavity for acceleration

MCTF 5-Year RF R&D Plan Page 7Derun Li - Lawrence Berkeley National Laboratory, Sep. 18, 2009 Dielectric Loaded RF Cavity Motivation: To fit pressurized cavities in HCC, size of cavity has to be reducedTo fit pressurized cavities in HCC, size of cavity has to be reduced Examples:Examples: –800 MHz dielectric loaded cavity Maximum RF cavity radius = 8 cm, (pillbox cavity: 14.3 cm)Maximum RF cavity radius = 8 cm, (pillbox cavity: 14.3 cm) Radius of effective electric field (95 % from peak) = 3 cmRadius of effective electric field (95 % from peak) = 3 cm –400 MHz dielectric loaded cavity Maximum RF radius = 16 cmMaximum RF radius = 16 cm (pillbox cavity: 28.6 cm) (pillbox cavity: 28.6 cm) Radius of effective electric field = 6 cmRadius of effective electric field = 6 cm Dielectric ring

MCTF 5-Year RF R&D Plan Page 8Derun Li - Lawrence Berkeley National Laboratory, Sep. 18, 2009 Responsibility for MICE (RFCC Module) SC coupling Coil Cavity Couplers Vacuum Pump 201-MHz cavity Curved Be window August 29, 2009

MCTF 5-Year RF R&D Plan Page 9Derun Li - Lawrence Berkeley National Laboratory, Sep. 18, 2009 Summary Muon Ionization Cooling Channel requires normal conducting RF cavity operating in a few Tesla magnetic fieldMuon 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 well201-MHz RF cavity for MICE progressing well –The first five cavities expect to be delivered to LBNL in Nov –Superconducting coupling coil contract to be awarded soon Plans for RF breakdown studiesPlans for RF breakdown studies –Vacuum cavity 805-MHz button cavity and box cavity tests805-MHz button cavity and box cavity tests 201-MHz cavity test to be resumed soon201-MHz cavity test to be resumed soon Beryllium cavity design starts soonBeryllium cavity design starts soon ALD processed cavity to eliminate field emissionALD processed cavity to eliminate field emission Dielectric loaded cavityDielectric loaded cavity –High pressured RF cavity tests