201 mhz cavity fabrication update
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201 MHz Cavity Fabrication Update. Derun Li Lawrence Berkeley National Lab. MICE CM24 at RAL, UK June 1, 2009. SC coupling Coil. Curved Be window. Cavity Couplers. Vacuum Pump. 201-MHz cavity. Four RF Cavities in each RFCC Module. RFCC PDR and FDR completed during CM21 and CM22

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201 MHz Cavity Fabrication Update

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201 mhz cavity fabrication update

201 MHz Cavity Fabrication Update

Derun Li

Lawrence Berkeley National Lab

MICE CM24 at RAL, UK

June 1, 2009


Four rf cavities in each rfcc module

SC coupling Coil

Curved

Be window

Cavity Couplers

Vacuum Pump

201-MHz cavity

Four RF Cavities in each RFCC Module

Derun Li - Lawrence Berkeley National Lab – June 1, 2009


201 mhz cavity fabrication update

RFCC PDR and FDR completed during CM21 and CM22

201 MHz cavity detailed design and analysis were complete at CM23

Qualification of three cavity fab vendors completed late last year

RFP for cavity fabrication released by LBNL in January 2009

Copper cavity material arrived at LBNL in January 2009

Cavity fabrication has been awarded to Applied Fusion in Feb. 2009

Cavity body fabrication started in April 2009

A slight reduction in cavity diameter to raise the frequency has been specified and analyzed

Visited ACME Spinning

re-spun two spare half shells to the new cavity profile and measured frequency shifts

Developed cavity body fabrication procedures (based on lessons learned from the MuCool prototype)

The first 5 cavities to be delivered by end of CY2009 with option to purchase 5 additional cavities

Progress Summary (1/2)

Derun Li - Lawrence Berkeley National Lab – June 1, 2009


201 mhz cavity fabrication update

Other components:

Cavity tuner RF & structural analyses and CAD model are in progress

Structural analyses of cavity suspension system is complete

RF coupler based on design previously developed for MuCool cavity

Ceramic RF windows (SNS window, off-shelf component)

Cavity cooling water feed-through concept has been developed

Beryllium windows

Purchase order placed with Brush Wellman Company

Cavity and vacuum vessel interface with CC

In progress

Progress Summary (2/2)

Derun Li - Lawrence Berkeley National Lab – June 1, 2009


201 mhz cavity fabrication update

Update on MICE RF Cavity Design

  • 3-Dimensional RF cavity parameterized model to study frequency shifts from RF ports and curved Be windows and Epeak

  • Frequencies variation between cavities should be within  100 kHz

  • Fabrication

    • Modification of the mold for prototype cavity

      • Reduction in diameter to raise the MICE cavity frequency

    • Tune cavities close to design frequency by deformation of cavity body (if needed)

    • Fine tuners operate in the push-and-pull mode  230 kHz

Derun Li - Lawrence Berkeley National Lab – June 1, 2009


201 mhz cavity fabrication update

Cavity Design Parameters

  • The cavity design parameters

    • Frequency: 201.25 MHz

    • β = 0.87

    • Shunt impedance (VT2/P): ~ 22 MΩ/m

    • Quality factor (Q0): ~ 53,500

    • Be window diameter and thickness: 42-cm and 0.38-mm

  • Nominal parameters forMICEand cooling channels in a neutrino factory

    • 8 MV/m(~16 MV/m)peak accelerating field

    • Peak input RF power:1 MW(~4.6 MW)per cavity

    • Average power dissipation per cavity:1 kW(~8.4 kW)

    • Average power dissipation per Be window:12 w(~100 w)

Derun Li - Lawrence Berkeley National Lab – June 1, 2009


201 mhz cavity concept

201 MHz Cavity Concept

Spinning of half shells using thin copper sheets and e-beam welding to join the shells; extruding of four ports; each cavity has two pre-curved beryllium windows, but also accommodates different windows

Derun Li - Lawrence Berkeley National Lab – June 1, 2009


201 mhz cavity fabrication update

Visit to ACME Spinning in April 2009 (1/3)

  • Machined the MuCool mold to the new profile

  • Re-spun the two half spare shells to new profile

  • Measured frequency shifts before and after spinning

Expected frequency shift ~ 1 MHz

Measurements:

Shell #1:

197.275 MHz (before)

198.180 MHz (after)

Derun Li - Lawrence Berkeley National Lab – June 1, 2009


201 mhz cavity fabrication update

Visit to ACME Spinning in April 2009 (2/3)

  • Spun and measured a new half shell (frequency: 198.415 MHz)

  • Developed a fabrication procedure

    • Pre-polishing copper sheets

    • Inspecting the surface

    • Polishing visible scratches locally if necessary (before and after)

    • Handling and shipping

Polished surface

Local polishing to remove

deeper scratches

Surface inspection during

the spinning

Derun Li - Lawrence Berkeley National Lab – June 1, 2009


201 mhz cavity fabrication update

Visit to ACME Spinning in April 2009 (3/3)

  • Spinning of MICE cavity (April 22, 2009):

Derun Li - Lawrence Berkeley National Lab – June 1, 2009


201 mhz cavity fabrication update

Cavity Inspection at LBNL (1/2)

  • 12 spun half shells arrived LBNL in May 2009

  • CMM scans to pair best matches of two half shells in diameters, 8 of them have been measured so far

Center hole for

handling & spinning

Polished cavity

surface

Labeling each

shell

Derun Li - Lawrence Berkeley National Lab – June 1, 2009


201 mhz cavity fabrication update

Cavity Inspection at LBNL (2/2)

  • CMM scans to pair best matches of two half shells (diameters)

    • Over 1,500 points along the cavity perimeter

    • Find the best match of average radii, radius deviations and the location of the deviation angles

    • Examples of two shells

Radius deviations are

magnified by a factor of 55 here

Shell 4B (blue)

and 6B (yellow)

Derun Li - Lawrence Berkeley National Lab – June 1, 2009


201 mhz cavity fabrication update

Fabrication Status at Applied Fusion (1/2)

  • Fixtures used for the MuCool prototype shipped to Applied Fusion

  • Two re-spun half shells arrived Applied Fusion in early May for fabrication test/practice

    • E-beam welding tests

      • Stiffener rings

      • Equator

    • Port extruding

    • Water cooling pipes

E-beam welding of

the stiffener ring

Derun Li - Lawrence Berkeley National Lab – June 1, 2009


201 mhz cavity fabrication update

Fabrication Status at Applied Fusion (2/2)

Port extruding and flange

welding testing

E-beam strength testing

Derun Li - Lawrence Berkeley National Lab – June 1, 2009


201 mhz cavity fabrication update

Current Plan at Applied Fusion

  • June – September 2009:

    • Machine the shells and prep for EB

    • EBW stiffener rings

    • Equator welding

    • Port extruding (4 in each cavity)

    • Machine and weld port flanges

    • Machine-finish and EBW of the nose rings

    • Machine-finish and EBW of the nose rings

    • Tig-weld water cooling pipes

    • Vacuum check of the cavity and water cooling pipes

      Integration of cavities, coupling coils and other module components will take place at LBNL

Derun Li - Lawrence Berkeley National Lab – June 1, 2009


201 mhz cavity fabrication update

Schedule Summary (Presented at CM23)

Derun Li - Lawrence Berkeley National Lab – June 1, 2009


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