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MICE RFCC Module and 201 MHz Cavity
Update
Steve VirostekLawrence Berkeley National Lab
MICE CM23 at ICST, Harbin
January 15, 2009
RFCC Module and 201 MHz Cavity Update – MICE CM23 at ICST, Harbin, China
Page 2Steve Virostek - Lawrence Berkeley National Lab - January 15, 2009
Overview
• Engineering design of the RFCC module has been under way at LBNL since early last year
• Preliminary and final design reviews were conducted last year
• Coupling coil design and fabrication is being provided by ICST at Harbin (following talks)
• MICE cavity design is heavily based on the successful MuCool 201 MHz prototype RF cavity
– Fabrication techniques and post processing – Engineering design of the RF cavity is complete – Cavity fabrication contract to be placed soon
• Significant progress on RFCC module engineering design– Complete CAD model of the cavity, tuners, support and vacuum
– Interfaces, shipping, assembly and installation (earlier talk)
RFCC Module and 201 MHz Cavity Update – MICE CM23 at ICST, Harbin, China
Page 3Steve Virostek - Lawrence Berkeley National Lab - January 15, 2009
RFCC Module
SC coupling Coil
Cavity Couplers
Vacuum Pump201-MHz cavity201-MHz cavity
Curved Be window
RFCC Module and 201 MHz Cavity Update – MICE CM23 at ICST, Harbin, China
Page 4Steve Virostek - Lawrence Berkeley National Lab - January 15, 2009
Progress Summary
• RFCC PDR and FDR completed during CM21 and CM22• 201 MHz cavity detailed design and analysis is complete• Qualification of three cavity fab vendors completed late last year• RFP for cavity fab released by LBNL this week (responses due 1/30)• Copper cavity material to arrive at LBNL next week• Cavity tuner RF & structural analyses and CAD model are complete• Structural analyses of cavity suspension system is complete• RF coupler based on design previously developed for MuCool cavity• Coupling coil interface agreed upon with ICST (a few details remain)• Cavity cooling water feedthrough concept has been developed• Conceptual design and CAD model of module vacuum vessel,
vacuum system and support structure is complete• Shipping, assembly and installation presented earlier this week
RFCC Module and 201 MHz Cavity Update – MICE CM23 at ICST, Harbin, China
Page 5Steve Virostek - Lawrence Berkeley National Lab - January 15, 2009
Eight 201-MHz Cavities for MICE
Eight 201-MHz RF cavities
RFCC modules
RFCC Module and 201 MHz Cavity Update – MICE CM23 at ICST, Harbin, China
Page 6Steve Virostek - Lawrence Berkeley National Lab - January 15, 2009
MICE RF Cavity Summary
•Design based on the successful US MuCool prototype
•A slight reduction in cavity diameter to raise the frequency has been specified and analyzed
• The fabrication techniques used to produce the prototype will be used to fabricate the MICE RF cavities
• Final cavity design was reviewed at CM22 at RAL
•Copper cavity material will arrive at LBNL next week
•An RFP for cavity fabrication has been released, and a contract is expected to be placed next month
• The first 5 cavities to be delivered by end of CY2009
RFCC Module and 201 MHz Cavity Update – MICE CM23 at ICST, Harbin, China
Page 7Steve Virostek - Lawrence Berkeley National Lab - January 15, 2009
MICE RF Cavity Design
•3-D Microwave Studio RF parameterized model including ports and curved Be windows to simulate frequency, Epeak, etc.
•Frequencies variation between cavities should be within 100 kHz
•Approach–Slightly modify prototype cavity diameter
–Target a higher cavity frequency–Tune cavities close to design frequency by deformation of cavity body (if needed)
–Tuners operate in the push-in mode only lower frequency
RFCC Module and 201 MHz Cavity Update – MICE CM23 at ICST, Harbin, China
Page 8Steve Virostek - Lawrence Berkeley National Lab - January 15, 2009
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)
RFCC Module and 201 MHz Cavity Update – MICE CM23 at ICST, Harbin, China
Page 9Steve Virostek - Lawrence Berkeley National Lab - January 15, 2009
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
RFCC Module and 201 MHz Cavity Update – MICE CM23 at ICST, Harbin, China
Page 10Steve Virostek - Lawrence Berkeley National Lab - January 15, 2009
Cavity FEA Analysis• RF, thermal and
structural cavity analyses carried out using a single ANSYS model
• The thermal solution provides the temperature distribution throughout the cavity and Be window
• Heat fluxes on inward curving windows are 60% higher than for outward curving windows (with correspondingly higher T)
• Peak temperature occurs at center of inwardly curved beryllium window (86 ºC) using “Nominal Neutrino Factory” parameters (MICE is 4 times lower)
Cavity RF FEA Model
Temp plot w/window Temp plot w/o window
Cavity Body FEA Model
RFCC Module and 201 MHz Cavity Update – MICE CM23 at ICST, Harbin, China
Page 12Steve Virostek - Lawrence Berkeley National Lab - January 15, 2009
Cavity Fabrication Drawings
•Detailed fabrication drawings are complete
•All steps of cavity fabrication process are detailed
•Drawings provided to vendors for bidding process
RFCC Module and 201 MHz Cavity Update – MICE CM23 at ICST, Harbin, China
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Cavity Fabrication Process Traveler
RFCC Module and 201 MHz Cavity Update – MICE CM23 at ICST, Harbin, China
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•A series of vendor qualification visits were conducted
• Applied Fusion - San Leandro, CA– e-beam welding, machining
• Meyer Tool & Mfg., Inc. - Chicago, IL– machining
• Roark Welding & Engineering - Indianapolis, IN– e-beam welding, machining
• Sciaky, Inc. - Chicago, IL– e-beam welding
• ACME Metal Spinning – Minneapolis, MN– cavity shell spinning
• Midwest Metal Spinning, Inc. –Bedford, IN– cavity shell spinning
Cavity Vendor QualificationCavity Vendor Qualification
Primary vendors
RFCC Module and 201 MHz Cavity Update – MICE CM23 at ICST, Harbin, China
Page 15Steve Virostek - Lawrence Berkeley National Lab - January 15, 2009
Meyer Tool & Manufacturing, Inc.4601 W. Southwest HighwayOak Lawn, Illinois 60453
•Meyer uses Sciaky’s e-beam welding service at the Sciaky factory close to Meyer Tool (Sciaky is a major e-beam welder manufacturer)
•Meyer Tool has the machining equipment necessary to fabricate the complete RF cavity (minus spinning)
• A complete drawing package, specification and request for quote has been presented to Meyer Tool
Meyer Tool & Manufacturing
Sciaky electron beam welding machine
RFCC Module and 201 MHz Cavity Update – MICE CM23 at ICST, Harbin, China
Page 16Steve Virostek - Lawrence Berkeley National Lab - January 15, 2009
C.F. Roark Welding & Engineering Co, Inc.136 N. Green St.Brownsburg, IN 46112•Roark Welding’s e-beam welder is a Sciaky machine and it is housed in an isolated room with a positive air flow to help maintain cleanliness
•Roark Welding has the machining equipment necessary to fabricate the complete RF cavity (plus spinning at an outside vendor)
•A complete drawing package, specification and request for quote has been presented to Roark Welding
C.F. Roark Welding & Engineering Co, Inc.
Sciaky electron beam welding machine at Roark
RFCC Module and 201 MHz Cavity Update – MICE CM23 at ICST, Harbin, China
Page 17Steve Virostek - Lawrence Berkeley National Lab - January 15, 2009
Applied Fusion, Inc.Applied Fusion, Inc.1915 Republic Ave.San Leandro, CA 94577
• Applied Fusion’s e-beam welder is a German made machine
• Applied Fusion has the machining equipment necessary to fabricate the complete RF cavity (minus spinning)
• A complete drawing package, specification and request for quote has been presented to Applied Fusion
Electron beam welding machine
RFCC Module and 201 MHz Cavity Update – MICE CM23 at ICST, Harbin, China
Page 18Steve Virostek - Lawrence Berkeley National Lab - January 15, 2009
Overall RFCC Module Design
Dynamic Cavity Frequency Tuners
Hexapod StrutCavity Suspension RF Cavity
Water Cooling
Mechanical Joiningof the Coupling Coiland the Vacuum Vessel
Vacuum System
RF Coupler
RFCC Module and 201 MHz Cavity Update – MICE CM23 at ICST, Harbin, China
Page 19Steve Virostek - Lawrence Berkeley National Lab - January 15, 2009
Progress: Other Module Components
• Design and analysis of the cavity frequency tuners is complete, drawings to be done soon
• A hexapod cavity suspension system has been incorporated in the design
• The RF coupler will be based on the SNS design using the off the shelf Toshiba RF window
• The vacuum system includes an annular feature coupling the inside and the outside of the cavity
• Vacuum vessel accommodates interface w/coupling coil
• Beryllium window design is complete; windows are in the process of being ordered (8 per module needed)
RFCC Module and 201 MHz Cavity Update – MICE CM23 at ICST, Harbin, China
Page 20Steve Virostek - Lawrence Berkeley National Lab - January 15, 2009
Cavity Tuner Configuration
•Tuners touch cavity and apply loads only at the stiffener rings
•Tuners operate in “push” mode only (i.e. squeezing)
•Tuning automatically achieved through a feedback loop
•Soft connection only (bellows) between tuner/actuators and vacuum vessel shell
•Six tuners are spaced evenly every 60º around cavity
•Clocking of tuner position between adjacent cavities avoids interference
•No contact between pairs of close packed cavities
RFCC Module and 201 MHz Cavity Update – MICE CM23 at ICST, Harbin, China
Page 21Steve Virostek - Lawrence Berkeley National Lab - January 15, 2009
Cavity Tuner Components - Section View
Ball contact only
Dual bellowsvacuum sealing
Tuner actuator Pivot pin
Fixed (bolted)connection
Ceramic contact wear plate between actuator ball end and tuner arm
RFCC Module and 201 MHz Cavity Update – MICE CM23 at ICST, Harbin, China
Page 22Steve Virostek - Lawrence Berkeley National Lab - January 15, 2009
Tuner Component Details
Fixed arm
Pivoting arm
Actuator with integrated bellowsassembly
Screws to attach tuner to the cavity stiffener ring
Pivot pinCylinder attachment bracket
Forces are transmitted to the stiffener ring by means of “push” loads applied to the tuner lever arms by the actuator assembly
RFCC Module and 201 MHz Cavity Update – MICE CM23 at ICST, Harbin, China
Page 23Steve Virostek - Lawrence Berkeley National Lab - January 15, 2009
Tuner Actuator Design
•Actuator design uses dual bellows vacuum-to-air sealing (no rubber)
•Actuator is “soft” mounted to the vacuum vessel with a bellows
Ceramic plate on tuner arm
Hemisphere on actuator rod end
•Senior Aerospace Bellows will supply the actuators (near off the shelf)
RFCC Module and 201 MHz Cavity Update – MICE CM23 at ICST, Harbin, China
Page 24Steve Virostek - Lawrence Berkeley National Lab - January 15, 2009
Cavity Tuning Parameters
The following parameters are based on a finite element analysis of the cavity shell. Tuning range is limited by material yield stress.
•Overall cavity stiffness: 7953 N/mm
•Tuning sensitivity: +230 kHz/mm per side
•Tuning range: 0 to -460 kHz (0 to -2 mm per side)
•Number of tuners: 6
•Maximum ring load/tuner: 5.3 kN
•Max actuator press. (100 mm): 1.38 MPa (200 psi)
RFCC Module and 201 MHz Cavity Update – MICE CM23 at ICST, Harbin, China
Page 25Steve Virostek - Lawrence Berkeley National Lab - January 15, 2009
Tuner System Analysis• Model of overall cavity tuning
displacements• Maximum distortion of 0.05
mm (0.002”) in the stiffener ring
• One tuner FEA of 1/6 cavity segment• Maximum cavity stress is 100 MPa• Cavity will not yield when
compressed to full tuning range
RFCC Module and 201 MHz Cavity Update – MICE CM23 at ICST, Harbin, China
Page 26Steve Virostek - Lawrence Berkeley National Lab - January 15, 2009
Cavity Support: Hexapod Strut System
Example of a hexapod stage
•Dedicated six-strut hexapod system for each cavity will provide kinematic support
•This system spreads the cavity weight across several struts
•Strut arrangement provides stiff and accurate cavity support
•Kinematic mounts prevent high cavity stresses due to thermal distortion and over-constraint
RFCC Module and 201 MHz Cavity Update – MICE CM23 at ICST, Harbin, China
Page 27Steve Virostek - Lawrence Berkeley National Lab - January 15, 2009
Hexapod Strut Cavity Mounts
•Copper mounting block will be e-beam welded directly to the RF cavity
•The cavity is very stiff at mounting block location
•Opposite end of strut connects to stainless steel mounting block welded to the vacuum vessel
RFCC Module and 201 MHz Cavity Update – MICE CM23 at ICST, Harbin, China
Page 28Steve Virostek - Lawrence Berkeley National Lab - January 15, 2009
Hexapod Strut Mounting to Vessel
Stainless steel strut mounts welded to the inside of the vacuum vessel
Copper strut mounts e-beam welded to the outside of the cavity
RFCC Module and 201 MHz Cavity Update – MICE CM23 at ICST, Harbin, China
Page 29Steve Virostek - Lawrence Berkeley National Lab - January 15, 2009
Cavity Suspension AnalysisCavity Suspension Analysis
Stress Analysis•Peak cavity stress due
to gravity is the 20-30 MPa (~10% of yield)
Deflection Analysis•Total mass of cavity
assembly is ~410 kg•Peak deflection: 115 m
Modal Analysis• First mode
frequency: 43 Hz
RFCC Module and 201 MHz Cavity Update – MICE CM23 at ICST, Harbin, China
Page 30Steve Virostek - Lawrence Berkeley National Lab - January 15, 2009
Cavity Cooling System
•Single circuit water cooling tube for each cavity
•One inlet and one outlet
•8 penetrations in the vacuum vessel
RFCC Module and 201 MHz Cavity Update – MICE CM23 at ICST, Harbin, China
Page 31Steve Virostek - Lawrence Berkeley National Lab - January 15, 2009
Cavity Cooling Water Feedthroughs
•All cavity water connections are made outside of the vacuum vessel
•Continuous water tube wrapped around the cavity
•Compliance coil inside of the vacuum vessel
•One inlet and one outlet per cavity
RFCC Module and 201 MHz Cavity Update – MICE CM23 at ICST, Harbin, China
Page 32Steve Virostek - Lawrence Berkeley National Lab - January 15, 2009
Section View of Water Feedthroughs
•A conflat flange is welded into the wall of the vacuum vessel
•Ends of copper tubes are brazed into a 2nd special conflat flange
• The flange is fastened from the outside of the vacuum vessel
Vacuum side
Air side
RFCC Module and 201 MHz Cavity Update – MICE CM23 at ICST, Harbin, China
Page 33Steve Virostek - Lawrence Berkeley National Lab - January 15, 2009
Prototype Cavity RF Couplers
•Coupling loops are fabricated using standard copper co-ax
•Parts to be joined by e-beam welding (where possible) and torch brazing
•Coupling loop has integrated cooling
•The RF coupler will be based on the SNS design using the off the shelf Toshiba RF window
RFCC Module and 201 MHz Cavity Update – MICE CM23 at ICST, Harbin, China
Page 34Steve Virostek - Lawrence Berkeley National Lab - January 15, 2009
MICE Cavity RF Couplers
•A bellows connection between the coupler and the vacuum vessel provides compliance for mating with the cavity
RFCC Module and 201 MHz Cavity Update – MICE CM23 at ICST, Harbin, China
Page 35Steve Virostek - Lawrence Berkeley National Lab - January 15, 2009
MICE Cavity RF Couplers
Off the shelf flange “V” clamp secures RF coupler to cavity
RFCC Module and 201 MHz Cavity Update – MICE CM23 at ICST, Harbin, China
Page 36Steve Virostek - Lawrence Berkeley National Lab - January 15, 2009
Vacuum System
•A NEG pump has been chosen because it will be unaffected by the large magnetic field
•A vacuum path between the inside and outside of the cavity eliminates the risk of high pressure differentials and the possible rupture of the thin beryllium window
NEG (non-evaporable getter) pump
Cross-sectional view of vacuum system
RFCC Module and 201 MHz Cavity Update – MICE CM23 at ICST, Harbin, China
Page 37Steve Virostek - Lawrence Berkeley National Lab - January 15, 2009
Vacuum Vessel Fabrication
• Vacuum vessel material must be non-magnetic and strong therefore 304 stainless steel will be used
• The vacuum vessel will be fabricated by rolling stainless steel sheets into cylinders
• Two identical vessel halves will be fabricated with all ports and feedthroughs
Main 1400mm rolled tube
Smaller diameter rolled tube
Bellowsflange
RFCC Module and 201 MHz Cavity Update – MICE CM23 at ICST, Harbin, China
Page 38Steve Virostek - Lawrence Berkeley National Lab - January 15, 2009
Two Halves Joined (w/o coupling coil)
• Central under-cut provides clearance for the coupling coil
RFCC Module and 201 MHz Cavity Update – MICE CM23 at ICST, Harbin, China
Page 39Steve Virostek - Lawrence Berkeley National Lab - January 15, 2009
Vacuum Vessel and Coupling Coil
RFCC Module and 201 MHz Cavity Update – MICE CM23 at ICST, Harbin, China
Page 41Steve Virostek - Lawrence Berkeley National Lab - January 15, 2009
Vacuum Vessel Interface to Coupling Coil
•LBNL will weld two 25 mm thick special gussets, which are designed to match the gusset welded to the coupling coil at Harbin, to the vacuum vessel
RFCC Module and 201 MHz Cavity Update – MICE CM23 at ICST, Harbin, China
Page 42Steve Virostek - Lawrence Berkeley National Lab - January 15, 2009
• Sixteen gussets will be used, 8 on each side of coupling coil
Vacuum Vessel Interface to Coupling Coil
RFCC Module and 201 MHz Cavity Update – MICE CM23 at ICST, Harbin, China
Page 43Steve Virostek - Lawrence Berkeley National Lab - January 15, 2009
RFCC Module Support Stand
• Because a special skid will be used for shipping and moving the RFCC into the experiment hall, the permanent support stand is bolted onto the vacuum vessel (not welded)
• The support stand will be fabricated of stainless steel
RFCC Module and 201 MHz Cavity Update – MICE CM23 at ICST, Harbin, China
Page 44Steve Virostek - Lawrence Berkeley National Lab - January 15, 2009
RFCC Attachment to Support Stand
•The vacuum vessel is bolted to a saddle made of stainless steel plates welded to the support stand
•Stainless steel bars are welded onto the vacuum vessel for attaching bolted gusset plates
Bolted gusset mounting bars
RFCC Module and 201 MHz Cavity Update – MICE CM23 at ICST, Harbin, China
Page 45Steve Virostek - Lawrence Berkeley National Lab - January 15, 2009
RFCC Support Stand
• RFCC support stand must withstand a longitudinal force of 50 tons transferred from the coupling coil
• Bolted gussets and cross bracing provide shear strength in the axial direction (analysis will be done to confirm this stand design)
RFCC Module and 201 MHz Cavity Update – MICE CM23 at ICST, Harbin, China
Page 48Steve Virostek - Lawrence Berkeley National Lab - January 15, 2009
Schedule Overview
•RFCC design and fabrication project originally expected to be a 3–year project (10/06 to 10/09)
•Coupling coil effort began in 2006 at ICST (Harbin)
•Design and fabrication of other RFCC module components was scheduled to begin 10/07
•Start was delayed due to lack of availability of qualified manpower
•Earlier last year, mechanical engineer A. DeMello joined MICE to work on RFCC module design (FTE)
•Some additional (part-time) manpower now available
RFCC Module and 201 MHz Cavity Update – MICE CM23 at ICST, Harbin, China
Page 49Steve Virostek - Lawrence Berkeley National Lab - January 15, 2009
Manpower Summary
•Allan DeMello: lead ME for RFCC Module design & fab
−3D engineering CAD model, cavity analysis, design & fab
−Full-time on RFCC module design
•Nord Andresen: design/fab of module subcomponents
−Cavity tuners, support structure, vacuum vessel, procurements
−generation of fabrication drawings
−50% time design/engineering support
•Steve Virostek: engineering oversight for MICE at LBNL
•Derun Li: cavity physics design and oversight
•Mike Green: coupling coil design & interface with module
RFCC Module and 201 MHz Cavity Update – MICE CM23 at ICST, Harbin, China
Page 50Steve Virostek - Lawrence Berkeley National Lab - January 15, 2009
Schedule Summary