5-Year RF R&D Plan Derun Li Lawrence Berkeley National Laboratory NFMCC and MCTF Phone Meeting...

5-Year RF R&D Plan

Derun LiLawrence Berkeley National Laboratory

NFMCC and MCTF Phone Meeting

Friday, September 18, 2009

MCTF

Derun Li - Lawrence Berkeley National Laboratory, Sep. 18, 2009

5-Year RF R&D Plan

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

MCTF


5-Year RF R&D Plan

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.

– 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 this a 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 cavity5-Year RF R&D Plan

MCTF


5-Year RF R&D Plan

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)

MCTF


5-Year RF R&D Plan

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

MCTF


5-Year RF R&D Plan

Dielectric Loaded RF CavityMotivation:• 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 cmDielectric ring

MCTF


5-Year RF R&D Plan

Responsibility for MICE (RFCC Module)

SC coupling Coil

Cavity Couplers

Vacuum Pump201-MHz cavity

Curved Be window

August 29, 2009

MCTF


5-Year RF R&D Plan

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

5-Year RF R&D Plan Derun Li Lawrence Berkeley National Laboratory NFMCC and MCTF Phone Meeting...

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