progress on the mice rfcc module

Progress on the MICE RFCC Progress on the MICE RFCC Module Module

Mike Zisman/Steve VirostekMike Zisman/Steve VirostekLawrence Berkeley National LaboratoryLawrence Berkeley National Laboratory

MuCool Test Area RF Workshop October 15, 2008

Progress on the MICE RFCC Module

Zisman/Virostek - LBNL - October 15, 2008

Progress SummaryProgress Summary• The MICE cavity design is heavily based on the The MICE cavity design is heavily based on the

successful MuCool 201-MHz prototype RF cavity and successful MuCool 201-MHz prototype RF cavity and lessons learned lessons learned – Fabrication and post processing Fabrication and post processing – Cavity conditioning and operationCavity conditioning and operation

• Engineering design of the cavity is completeEngineering design of the cavity is complete – CAD model of the cavity, tuners, support and vacuum CAD model of the cavity, tuners, support and vacuum – Fabrication schemes and vendor identificationFabrication schemes and vendor identification

• RFCC module engineering design nearing completionRFCC module engineering design nearing completion• Possible operation at LN temperature?Possible operation at LN temperature?

– Design accommodates LN operation, but is very challenging Design accommodates LN operation, but is very challenging



Muon Ionization Cooling Muon Ionization Cooling ExperimentExperiment

SpectrometerSpectrometerSolenoid 1Solenoid 1

SpectrometerSpectrometerSolenoid 2Solenoid 2Absorber andAbsorber and

Focusing Coil (AFC)Focusing Coil (AFC)

AFCAFCAFCAFC

RFCCRFCC RFCCRFCC



2 RFCC Modules, 8 Cavities2 RFCC Modules, 8 CavitiesSC coupling Coil

Cavity Couplers

Vacuum Pump201-MHz cavity201-MHz cavity

Curved Be window



RF Cavity Summary• Fabrication of the prototype cavity was

successful• 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

• A detailed WBS schedule for the design and fabrication of the MICE RF cavities has been developed



Cavity Design ParametersCavity Design Parameters• Cavity design parameters:Cavity design parameters:

– Frequency: 201.25 MHzFrequency: 201.25 MHz– ββ = 0.87 = 0.87– Shunt impedance (VTShunt impedance (VT22/P): ~ 22 MΩ/m/P): ~ 22 MΩ/m– Quality factor (QQuality factor (Q00): ~ 53,500): ~ 53,500– Be window diameter and thickness: 42-cm and 0.38-mmBe window diameter and thickness: 42-cm and 0.38-mm

• Nominal parameters for Nominal parameters for MICEMICE and cooling channels and cooling channels in a neutrino factory:in a neutrino factory: – 8 MV/m8 MV/m (~16 MV/m)(~16 MV/m) peak accelerating fieldpeak accelerating field– Peak input RF power:Peak input RF power: 1 MW1 MW (~4.6 MW)(~4.6 MW) per cavity per cavity – Average power dissipation per cavity:Average power dissipation per cavity: 1 kW1 kW (~8.4 kW)(~8.4 kW)– Average power dissipation per Be window:Average power dissipation per Be window: 12 watts12 watts (~100 (~100

watts)watts)



Recent Progress: RF Cavity Recent Progress: RF Cavity DesignDesign

– 3-D Microwave Studio RF parameterized 3-D Microwave Studio RF parameterized model with ports and curved Be model with ports and curved Be windows windows

– Hard to reach the design frequency by Hard to reach the design frequency by spinning spinning

– Frequencies between cavities should be Frequencies between cavities should be able to achieve within able to achieve within 100 kHz 100 kHz

– ApproachesApproaches• Modification the spinning form Modification the spinning form • Targeting for higher frequencyTargeting for higher frequency• Fixed tuner to tune cavity close to Fixed tuner to tune cavity close to

design frequency (deformation of design frequency (deformation of cavity body)cavity body)

• Tuners are in push-in mode Tuners are in push-in mode lower lower frequencyfrequency



Numerical Study with B FieldNumerical Study with B Field• Preliminary studies, in collaboration with colleagues at SLAC Preliminary studies, in collaboration with colleagues at SLAC

using Omega-3P and Track-3P codesusing Omega-3P and Track-3P codes– Cavity with flat windows:Cavity with flat windows: 5 MV/m5 MV/m on axis;on axis; 2-T2-T uniform external uniform external

magnetic field; scan of a few points from one cavity sidemagnetic field; scan of a few points from one cavity side

E field contourE field contourTrajectories without Trajectories without

external B fieldexternal B fieldTrajectories with Trajectories with

external B = 2-T fieldexternal B = 2-T field



High Power RF Tests on Prototype High Power RF Tests on Prototype CavityCavity

• The cavity was first tested with flat copper windows and The cavity was first tested with flat copper windows and reached ~ 16 MV/m quickly and quietly reached ~ 16 MV/m quickly and quietly

• The cavity then was tested with thin and curved Be The cavity then was tested with thin and curved Be windows and again reached to ~19 MV/m quicklywindows and again reached to ~19 MV/m quickly– Cavity frequency had to be retuned Cavity frequency had to be retuned – Cavity frequency wasCavity frequency was stable stable during the operation, however, during the operation, however,

we did observe frequency shift due to RF heating on the we did observe frequency shift due to RF heating on the windowswindows

• Frequency shift of ~ 125 kHz (from 0 to ~ 19 MV/m, 150-micro-Frequency shift of ~ 125 kHz (from 0 to ~ 19 MV/m, 150-micro-second pulse, 10-Hz repetition rate) in ~ 10 minutes, well within second pulse, 10-Hz repetition rate) in ~ 10 minutes, well within the tuning range (230 kHz/mm per side, the tuning range (230 kHz/mm per side, 2-mm range) 2-mm range)

– With a few hundred Gauss stray field from Lab-G magnet, With a few hundred Gauss stray field from Lab-G magnet, the cavity gradient can be maintained at 19 MV/mthe cavity gradient can be maintained at 19 MV/m

• To test with stronger external magnetic fieldsTo test with stronger external magnetic fields– Move the cavity closer to Lab-G magnetMove the cavity closer to Lab-G magnet– SC coupling coil for MuCoolSC coupling coil for MuCool



Tests with Stronger Magnetic Tests with Stronger Magnetic FieldsFields• New vacuum pumping systemNew vacuum pumping system

• Separation of the nearest curved Separation of the nearest curved Be window from the face of Lab-Be window from the face of Lab-G magnet is 10-cm (before was G magnet is 10-cm (before was 110-cm)110-cm)

• Maximum magnetic field near the Maximum magnetic field near the Be window 1.5 Tesla (at 5 Tesla Be window 1.5 Tesla (at 5 Tesla in magnet)in magnet)

Test Results:Test Results:• Multipactoring was observed over Multipactoring was observed over

the entire magnetic field range up to the entire magnetic field range up to 1.1-T at nearest Be window1.1-T at nearest Be window

• A strong correlation exists between A strong correlation exists between cavity vacuum and radiation levelscavity vacuum and radiation levels

• We have achieved ~ 14 MV/m at 0.75-We have achieved ~ 14 MV/m at 0.75-T to the nearest curved thin Be T to the nearest curved thin Be windowwindowRecent test results show plateau at Recent test results show plateau at

~10 MV/m ~10 MV/m

The 201-MHz cavityThe 201-MHz cavity

Lab-G magnetLab-G magnet



RF Cavity AssemblyRF Cavity Assembly



RF Cavity Fabrication RF Cavity Fabrication OverviewOverview

• Cavity half-shells to be formed by metal spinning

• Precision milling of large parts (1.2 m diameter)

• Precision turning of mid-sized parts (0.6 m dia.)

• Precision manufacture of smaller parts• CMM measurements throughout the process• To limit any annealing and maintain cavity

strength, e-beam welding will be used for all cavity welding

• cavity equator, stiffener rings, nose rings, port annealing and port flanges

• Cavity inside surfaces are finished by electro-polishing

Engineering CAD

Model of the RF Cavity

Prototype RF Cavity

The same fabrication techniques used to make the prototype cavity will be used for the MICE RF cavities



Recent ProgressRecent Progress• RFCC engineering CAD model refinedRFCC engineering CAD model refined• RF and engineering design of 201-MHz RF cavity RF and engineering design of 201-MHz RF cavity

completecomplete• Integration and interface issues addressedIntegration and interface issues addressed• Vendor identification and qualification near completeVendor identification and qualification near complete



Recent Progress (procurement Recent Progress (procurement && fab) fab)

•The large copper sheets used in the fabrication of the cavity shells have been ordered and will arrive at LBNL in mid-December

•A series of vendor qualification visits has been conducted•Applied Fusion - San Leandro, CA (e-beam welding, machining)•Meyer Tool & Mfg., Inc. - Chicago, IL (machining)•Sciaky, Inc. - Chicago, IL (e-beam welding)•Roark Welding & Engineering - Indianapolis, IN (e-beam welding,

machining)•ACME Metal Spinning – Minneapolis, MN (cavity shell spinning)

•Other vendors have been identified•Midwest Metal Spinning, Inc. –Bedford, IN (cavity shell spinning)



Other Module Components• Beryllium window design is complete; windows are

in the process of being ordered (8 per module needed)

• 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 (further analysis of vacuum rupture scenarios TBD)



Other Module ComponentsOther Module Components

Beryllium Window

Dynamic Tuners

Cavity Suspension

Vacuum System

RF Coupler



• Each cavity has two Be windowsEach cavity has two Be windows– 42-cm diameter and 0.38-mm thick 42-cm diameter and 0.38-mm thick – Window is formed at high temperature and later brazed to copper Window is formed at high temperature and later brazed to copper

frames frames – Thin TiN coatings on both sides of the windowThin TiN coatings on both sides of the window

• One window curves into the cavity and one curves outOne window curves into the cavity and one curves out• Already tested up to 5 MW in 201-MHz cavity at MTA, FNAL Already tested up to 5 MW in 201-MHz cavity at MTA, FNAL

42-cm42-cm

201 MHz Beryllium Windows201 MHz Beryllium Windows



Cavity Tuner Design FeaturesCavity Tuner Design Features•Six tuners spaced evenly

around each cavity provide individual frequency adjustment through a feedback loop

•Layout is offset by 15º from vertical to avoid conflict with cavity ports

•Tuners touch cavity and apply loads only at the stiffener rings

•Tuners operate in “push” mode only (i.e. squeezing)



Tuner component DetailsTuner component Details

Fixed arm

Pivoting arm

Actuator& bellowsassembly

Forces are transmitted to the stiffener ring by means of “push” loads applied to the tuner lever arms by the actuator assembly



Hexapod Strut ArrangementHexapod Strut Arrangement•Analysis of a hexapod strut system is complete

•Each cavity will contain a dedicated set of 6 suspension struts arranged in a hexapod type formation

•This system spreads the gravity load of the cavity across several struts

Example of a hexapod stage



Hexapod Strut Cavity Hexapod Strut Cavity MountingMounting

•Copper mounting block will be e-beam welded directly to the RF cavity

•The cavity has very little deformation at the mounting block location



Vacuum SystemVacuum 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



Vacuum Vessel and Support Vacuum Vessel and Support SummarySummary

• Engineering 3D CAD model of the vacuum vessel mechanical design is complete

• Standard machining and manufacturing methods will be used

• A plan for attaching the coupling coil and the vacuum vessel together has been developed

• Conceptual design of the support stand is complete (analysis will need to be performed)

• A method for assembling the cavities into the vacuum vessel has been formulated

• A conceptual design of the cavity water cooling feedthrough system is finished



Vacuum Vessel FabricationVacuum Vessel Fabrication•Vacuum vessel material must be non-magnetic and strong therefore

304 stainless steel will be used throughout•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



Vacuum Vessel and Coupling Vacuum Vessel and Coupling CoilCoil



Vacuum Vessel/Coupling Coil Vacuum Vessel/Coupling Coil IntegrationIntegration

• LBNL will weld in gussets that fit between the coupling coil and the vacuum vessel

• Sixteen special gussets are welded between the coupling coil magnet’s cold mass support tubes and the magnet housing

• The gussets will transfer the magnetic loads between the coupling coil and the vacuum vessel



RFCC Attachment to Support RFCC Attachment to Support StandStand

• The vacuum vessel is bolted to a saddle made up of small 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 Support StandRFCC 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 confirm the stand design)



MICE RF Cavity – Mechanical Design and Analysis

Page 29Allan DeMello - Lawrence Berkeley National Lab - June 4, 2008

Liquid Nitrogen Cooling Considerations

•Suspension of cavities on struts provides low heat leak from cavity to vacuum vessel

•Beryllium window FEA thermal analysis will need to be performed with new parameters

•The cavity frequency will be shifted (approximately 600 kHz), therefore tuning system or RF power source modifications will be needed

•Insulators will need to be added to the RF couplers•Coaxial LN feedthrough tubes will be needed to insulate the connection outside of vacuum



Module Assembly SequenceBeryllium windows are

installed onto the cavitiesBare cavity



Module Assembly SequenceAssembly of the tuners onto

the cavities (w/o actuators)Install struts onto the cavity



Module Assembly Sequence• Slide the inner cavity into

vacuum vessel using spacer/alignment blocks for support

• Shim cavity to align tuner and coupler vacuum feedthroughs with tuner mounts and cavity ports

• After adjusting their lengths, secure the struts to the vacuum vessel mounting blocks



Module Assembly Sequence

Install tuner actuators

Install RF couplers

Install cooling water feedthroughs

Install vacuum couplers



Module Assembly SequenceRepeat the same process for the other cavities

Two cavities are installed from each

end of vacuum vessel

Install vacuum valves and pumps



RFCC Module Shipping RFCC Module Shipping ConfigurationConfiguration

Module short stand used for:

•Initial module assembly

•Shipping to RAL•Moving into MICE Hall

Cryocoolers removed

Cavities removed

Couplers removed

Vacuum pumps removed



MICE Hall AccessMICE Hall Access



Installation in MICE HallInstallation in MICE Hall•Module assembled on lateral tracks•Module aligned and shimmed to correct height

•Bellows on either end of module are pulled back into open position and O-ring in place

•Moved into position w/rails for final alignment

•Bellows are released and flanges are sealed

•Bellows are locked out using bridging bolts•RF and utilities are connected to module



Module Flange ConnectionModule Flange ConnectionEnd flange O-ring seal

Formed bellows

Flange through holes



Flanges and SealsFlanges and Seals•Flanges designed to mate with AFC module•AFC flanges are flat w/no grooves or bellows

•RFCC modules have bellows and O-ring grooves on flanges at either end

•Bellows have >1 cm of total travel•Bellows are locked out after installation to provide a means of transmitting forces between modules



Module Mounting ProvisionModule Mounting Provision• Six mounting plates welded to the

support base for installation on rails

• Same as spectrometer solenoid mounts

• All magnetic loads carried to the floor through the mounting plates



Cavity RF FeedsCavity RF Feeds•Eight RF feeds/module use standard 4” RF coax

•Cooling water for loop is required (<<1 lpm each)

•Adapter on end of couplers isolates ceramic RF windows from forces during installation

•Location of coax interface w.r.t. module center TBD

RF feeds



Schedule OverviewSchedule Overview•RFCC design and fabrication project originally RFCC design and fabrication project originally expected to be a 3–year project (10/06 to 10/09)expected to be a 3–year project (10/06 to 10/09)

•Coupling coil effort began in 2006 at ICST (Harbin)Coupling coil effort began in 2006 at ICST (Harbin)•Design and fabrication of other RFCC module Design and fabrication of other RFCC module components was scheduled to begin 10/07components was scheduled to begin 10/07

•Start was delayed due to lack of availability of Start was delayed due to lack of availability of qualified manpowerqualified manpower

•Earlier this year, mechanical engineer A. DeMello Earlier this year, mechanical engineer A. DeMello joined MICE to work on RFCC module design (FTE)joined MICE to work on RFCC module design (FTE)

•Additional manpower required to make up scheduleAdditional manpower required to make up schedule



Manpower SummaryManpower SummaryPrimary ManpowerPrimary Manpower•Allan DeMello: lead ME for RFCC Module design Allan DeMello: lead ME for RFCC Module design && fab fab

−3D engineering CAD model, cavity analysis, design 3D engineering CAD model, cavity analysis, design & fab& fab

•Steve Virostek: engineering oversight for MICE at LBNLSteve Virostek: engineering oversight for MICE at LBNL•Mechanical Engineer (TBD): design/fab of Mechanical Engineer (TBD): design/fab of

subcomponentssubcomponents−Cavity tuners, support structure, large procurementsCavity tuners, support structure, large procurements

•Mechanical Designer (TBD): generation of fabrication Mechanical Designer (TBD): generation of fabrication dwgsdwgs

OtherOther•Derun Li: cavity physics design and oversightDerun Li: cavity physics design and oversight•Mike Green: coupling coil design Mike Green: coupling coil design && interface with interface with

modulemodule



Schedule SummarySchedule Summary

progress on the mice rfcc module

Documents

prototype rf cavity

cavity diameter

cavity closer

cavity gradient

retuned cavity frequency

prototype cavitythe

rf heating

operationengineering