201 mhz cavity fabrication update derun li lawrence berkeley national lab mice cm24 at ral, uk june...

201 MHz Cavity Fabrication Update

Derun LiLawrence Berkeley National Lab

MICE CM24 at RAL, UK

June 1, 2009

201-MHz Cavity Fabrication Update, CM24, RAL, UK

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

Four RF Cavities in each RFCC Module

SC coupling Coil

Cavity Couplers

Vacuum Pump201-MHz cavity201-MHz cavity

Curved Be window



Progress Summary (1/2)

• 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 (2/2)

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



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



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 for MICE and 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)



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



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

•Machined the MuCool mold to the new profileMachined the MuCool mold to the new profile•Re-spun the two half spare shells to new profile Re-spun the two half spare shells to new profile • Measured frequency shifts before and after Measured frequency shifts before and after spinningspinning

Expected frequency shift ~ 1 MHzExpected frequency shift ~ 1 MHzMeasurements:Measurements: Shell #1:Shell #1:

197.275 MHz (before)197.275 MHz (before)198.180 MHz (after)198.180 MHz (after)




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

•Developed a fabrication procedureDeveloped a fabrication procedure• Pre-polishing copper sheetsPre-polishing copper sheets

• Inspecting the surface Inspecting the surface

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

• Handling and shippingHandling and shippingPolished surfacePolished surface

Local polishing to remove Local polishing to remove deeper scratches deeper scratches

Surface inspection during Surface inspection during the spinningthe spinning




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



Cavity Inspection at LBNL (1/2)• 12 spun half shells arrived LBNL in May 200912 spun half shells arrived LBNL in May 2009•CMM scans to pair best matches of two half shells in CMM scans to pair best matches of two half shells in

diameters, 8 of them have been measured so fardiameters, 8 of them have been measured so far

Polished cavity Polished cavity surfacesurface

Center hole for Center hole for handling & spinninghandling & spinning

Labeling eachLabeling eachshell shell



Cavity Inspection at LBNL (2/2)• CMM scans to pair best matches of two half shells CMM scans to pair best matches of two half shells

(diameters) (diameters) • Over 1,500 points along the cavity perimeter Over 1,500 points along the cavity perimeter • Find the best match of average radii, radius Find the best match of average radii, radius

deviations and the location of the deviation angles deviations and the location of the deviation angles • Examples of two shellsExamples of two shells

Shell 4B (blue) and 6B (yellow)

Radius deviations are magnified by a factor of 55 here



Fabrication Status at Applied Fusion (1/2)

•Fixtures used for the MuCool prototype shipped to Fixtures used for the MuCool prototype shipped to Applied FusionApplied Fusion

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

• E-beam welding testsE-beam welding tests• Stiffener ringsStiffener rings• Equator Equator

• Port extruding Port extruding • Water cooling pipes Water cooling pipes

E-beam welding of E-beam welding of the stiffener ringthe stiffener ring



Fabrication Status at Applied Fusion (2/2)

E-beam strength testingE-beam strength testing

Port extruding and flange Port extruding and flange welding testingwelding testing



Current Plan at Applied Fusion

• June – September 2009: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 flangesMachine and weld port flanges

― Machine-finish and EBW of the nose ringsMachine-finish and EBW of the nose rings

― Machine-finish and EBW of the nose ringsMachine-finish and EBW of the nose rings

― Tig-weld water cooling pipes Tig-weld water cooling pipes

― Vacuum check of the cavity and water cooling pipesVacuum check of the cavity and water cooling pipes

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



Schedule Summary (Presented at CM23)

201 mhz cavity fabrication update derun li lawrence berkeley national lab mice cm24 at ral, uk june...

Documents

cavity diameter

cavity conceptspinning

cavity detailed design

new cavity profile

deformation of cavity

copper cavity material

cavity fab vendors

design frequency