IntroductionIntroduction ToTo CryostatCryostat DesignDesign

J. G. Weisend II National Science Foundation SLAC National Accelerator Laboratory CourseCourse GoalsGoals

„ ProvideProvide anan introductionintroduction toto cryostatcryostat designdesign „ ExamineExamine cryostatscryostats asas integratedintegrated systemssystems ratherrather thenthen aa groupgroup ofof subsystemssubsystems „ ProvideProvide backgroundbackground informationinformation andand usefuluseful datadata „ ProvideProvide pointerspointers toto resourcesresources forfor moremore detaildetail „ ShowShow examplesexamples

Introduction to Cryostat Design J. G. Weisend II 11/10/2008 ICEC 2008 2 SyllabusSyllabus

„ IntroductionIntroduction „ CryostatCryostat RequirementsRequirements „ MaterialsMaterials SelectionSelection „ ThermalThermal IsolationIsolation andand HeatHeat LeakLeak „ StructuresStructures „ SafetySafety „ InstrumentationInstrumentation „ Seals,Seals, FeedFeed throughsthroughs andand BayonetsBayonets „ TransferTransfer LinesLines „ ExamplesExamples „ ReferencesReferences andand ResourcesResources

Introduction to Cryostat Design J. G. Weisend II 11/10/2008 ICEC 2008 3 IntroductionIntroduction

„ WhatWhat isis aa cryostat?cryostat? AA devicedevice oror systemsystem forfor maintainingmaintaining objectsobjects atat cryogeniccryogenic temperatures.temperatures.

„ CryostatsCryostats whosewhose principalprincipal functionfunction isis toto storestore cryogeniccryogenic fluidsfluids areare frequentlyfrequently calledcalled DewarsDewars.. NamedNamed afterafter thethe inventorinventor ofof thethe vacuumvacuum flaskflask andand thethe firstfirst personperson toto liquefyliquefy hydrogenhydrogen

Introduction to Cryostat Design J. G. Weisend II 11/10/2008 ICEC 2008 4 WhichWhich BringsBrings UsUs toto aa LimerickLimerick

““SirSir JamesJames DewarDewar isis aa betterbetter manman thanthan youyou areare NoneNone ofof youyou assesasses cancan liquefyliquefy gassesgasses”” Anon.Anon.

Introduction to Cryostat Design J. G. Weisend II 11/10/2008 ICEC 2008 5 IntroductionIntroduction

„ CryostatsCryostats areare oneone ofof thethe technicaltechnical buildingbuilding blocksblocks ofof cryogenicscryogenics „ ThereThere areare manymany differentdifferent typestypes ofof cryostatscryostats withwith differingdiffering requirementsrequirements „ TheThe basicbasic principlesprinciples ofof cryostatcryostat designdesign remainremain thethe samesame „ BeforeBefore wewe cancan dodo anythinganything elseelse wewe havehave toto definedefine ourour requirementsrequirements

Introduction to Cryostat Design J. G. Weisend II 11/10/2008 ICEC 2008 6 E158E158 LHLH2 2 TargetTarget CryostatCryostat

Introduction to Cryostat Design J. G. Weisend II 11/10/2008 ICEC 2008 7 CryostatCryostat RequirementsRequirements

„ MaximumMaximum allowableallowable heatheat leakleak atat variousvarious temperaturetemperature levelslevels „ This may be driven by the number of cryostats to be built as well as by the impact of large dynamic heat loads (SCRF or target cryostats) „ AlignmentAlignment andand vibrationvibration requirementsrequirements „ Impact of thermal cycles „ Need to adjust alignment when cold or under vacuum? „ Alignment tolerances can be quite tight (TESLA : +/- 0.5 mm for cavities and +/- 0.3 mm for SC magnets)

Introduction to Cryostat Design J. G. Weisend II 11/10/2008 ICEC 2008 8 CryostatCryostat RequirementsRequirements

„ NumberNumber ofof feedfeed throughsthroughs forfor power,power, instrumentation,instrumentation, cryogeniccryogenic fluidfluid flows,flows, externalexternal manipulatorsmanipulators „ SafetySafety requirementsrequirements (relief(relief valves/burstvalves/burst discs)discs) „ Design safety in from the start. Not as an add on „ SizeSize andand weightweight „ Particularly important in space systems „ InstrumentationInstrumentation requiredrequired „ Difference between prototype and mass production

Introduction to Cryostat Design J. G. Weisend II 11/10/2008 ICEC 2008 9 CryostatCryostat RequirementsRequirements

„ EaseEase ofof accessaccess toto cryostatcryostat componentscomponents „ ExistingExisting codecode requirementsrequirements (e.g.(e.g. TUVTUV oror ASME)ASME) „ Need,Need, ifif any,any, forfor opticaloptical windowswindows „ PresencePresence ofof ionizingionizing radiationradiation „ ExpectedExpected cryostatcryostat lifelife timetime „ WillWill thisthis bebe aa oneone ofof aa kindkind devicedevice oror somethingsomething toto bebe massmass produced?produced?

Introduction to Cryostat Design J. G. Weisend II 11/10/2008 ICEC 2008 10 CryostatCryostat RequirementsRequirements

„ ScheduleSchedule andand CostCost „ ThisThis shouldshould bebe consideredconsidered fromfrom thethe beginningbeginning

AllAll DesignDesign isis CompromiseCompromise

Introduction to Cryostat Design J. G. Weisend II 11/10/2008 ICEC 2008 11 MaterialMaterial SelectionSelection

„ MaterialMaterial propertiesproperties changechange significantlysignificantly withwith temperature.temperature. TheseThese changeschanges mustmust bebe allowedallowed forfor inin thethe design.design. „ ManyMany materialsmaterials areare unsuitableunsuitable forfor cryogeniccryogenic use.use. „ MaterialMaterial selectionselection mustmust alwaysalways bebe donedone carefully.carefully. TestingTesting maymay bebe required.required.

Introduction to Cryostat Design J. G. Weisend II 11/10/2008 ICEC 2008 12 MaterialMaterial SelectionSelection

„ Some suitable materials for cryogenic use include:

„ Austenitic stainless steels e.g. 304, 304L, 316, 321 „ Aluminum alloys e.g. 6061, 6063, 1100 „ Copper e.g. OFHC, ETP and phosphorous deoxidized „ Brass „ Fiber reinforced plastics such as G –10 and G –11 „ Niobium & Titanium (frequently used in superconducting RF systems) „ Invar (Ni /Fe alloy) useful in making washers due to its lower coefficient of expansion „ Indium (used as an O ring material) „ Kapton and Mylar (used in Multilayer Insulation and as electrical insulation „ Quartz (used in windows)

Introduction to Cryostat Design J. G. Weisend II 11/10/2008 ICEC 2008 13 MaterialMaterial SelectionSelection

„ UnsuitableUnsuitable materialsmaterials include:include:

„ Martensitic stainless steels Undergoes ductile to brittle transition when cooled down. „ Cast Iron – also becomes brittle „ Carbon steels – also becomes brittle. Sometimes used in 300 K vacuum vessels but care must be taken that breaks in cryogenic lines do not cause the vacuum vessels to cool down and fail. „ Rubber, Teflon and most plastics although plastic insulated wires are frequently OK as long as the wire is not repeatedly flexed which could lead to cracking of the insulation.

Introduction to Cryostat Design J. G. Weisend II 11/10/2008 ICEC 2008 14 ThermalThermal ExpansivityExpansivity

„ LargeLarge amountsamounts ofof contractioncontraction cancan occuroccur whenwhen materialsmaterials areare cooledcooled toto cryogeniccryogenic temperatures.temperatures. „ PointsPoints toto consider:consider: „ ImpactImpact onon alignmentalignment „ DevelopmentDevelopment ofof interferencesinterferences oror gapsgaps duedue toto dissimilardissimilar materialsmaterials „ IncreasedIncreased strainstrain andand possiblepossible failurefailure „ ImpactImpact onon wiringwiring „ MostMost contractioncontraction occursoccurs aboveabove 7777 KK

Introduction to Cryostat Design J. G. Weisend II 11/10/2008 ICEC 2008 15 ThermalThermal ExpansivityExpansivity

„ αα=1/L=1/L ((δδL/L/δδTT)) „ ResultsResults fromfrom anharmonicanharmonic componentcomponent inin thethe potentialpotential ofof thethe latticelattice vibrationvibration

Introduction to Cryostat Design J. G. Weisend II 11/10/2008 ICEC 2008 16 ThermalThermal ExpansivityExpansivity

„ α goes to 0 at 0 slope as T approaches 0 K „ α is T independent at higher temperatures „ For practical work the integral thermal contraction is more useful

Introduction to Cryostat Design J. G. Weisend II 11/10/2008 ICEC 2008 17 IntegralIntegral ThermalThermal ContractionContraction

Material ΔL / L ( 300 – 100 ) ΔL / L ( 100 – 4 )

Stainless Steel 296 x 10 -5 35 x 10 –5 Copper 326 x 10 -5 44 x 10 -5 Aluminum 415 x 10 -5 47 x 10 -5 Iron 198 x 10 -5 18 x 10 -5 Invar 40 x 10 -5 - Brass 340 x 10 –5 57 x 10 -5 Epoxy/ Fiberglass 279 x 10 –5 47 x 10 -5

Titanium 134 x 10 -5 17 x 10 -5

Introduction to Cryostat Design J. G. Weisend II 11/10/2008 ICEC 2008 18 IntegralIntegral ThermalThermal ContractionContraction

„ RoughlyRoughly speakingspeaking „ MetalsMetals –– 0.5%0.5% oror lessless „ PolymersPolymers –– 1.51.5 –– 3%3% „ SomeSome amorphousamorphous materialsmaterials havehave 00 oror eveneven negativenegative thermalthermal contractioncontraction

Introduction to Cryostat Design J. G. Weisend II 11/10/2008 ICEC 2008 19 HeatHeat CapacityCapacity oror SpecificSpecific HeatHeat ofof SolidsSolids

„ CC == dU/dTdU/dT oror Q/Q/mmΔΔTT „ InIn general,general, atat cryogeniccryogenic temperatures,temperatures, CC decreasesdecreases rapidlyrapidly withwith decreasingdecreasing temperature.temperature. „ ThisThis hashas 22 importantimportant effects:effects: „ SystemsSystems coolcool downdown fasterfaster asas theythey getget coldercolder „ AtAt cryogeniccryogenic temperatures,temperatures, smallsmall heatheat leaksleaks maymay causecause largelarge temperaturetemperature risesrises

Introduction to Cryostat Design J. G. Weisend II 11/10/2008 ICEC 2008 20 SpecificSpecific HeatHeat ofof SolidsSolids

„ WhereWhere isis thethe heatheat storedstored ?? „ LatticeLattice vibrationsvibrations „ ElectronsElectrons (metals)(metals) „ TheThe explanationexplanation ofof thethe temperaturetemperature dependencedependence ofof thethe specificspecific heatheat ofof solidssolids waswas anan earlyearly victoryvictory forfor quantumquantum mechanicsmechanics

Introduction to Cryostat Design J. G. Weisend II 11/10/2008 ICEC 2008 21 LatticeLattice ContributionContribution

„ DulongDulong PetitPetit LawLaw „ EnergyEnergy storedstored inin aa 3D3D oscillatoroscillator == 3NkT3NkT == 3RT3RT „ SpecificSpecific heatheat == 3R3R == constantconstant „ GenerallyGenerally OKOK forfor T=T= 300300 KK oror higherhigher „ DoesnDoesn’’tt taketake intointo accountaccount quantumquantum mechanicsmechanics

Introduction to Cryostat Design J. G. Weisend II 11/10/2008 ICEC 2008 22 EinsteinEinstein && DebyeDebye TheoriesTheories

„ EinsteinEinstein explainsexplains thatthat atomsatoms maymay onlyonly vibratevibrate atat quantizedquantized amplitudes.amplitudes. Thus:Thus: = ( + 2/1 )hnU υ

„ ThisThis resultsresults inin aa temperaturetemperature dependentdependent specificspecific heatheat „ DebyeDebye theorytheory accountsaccounts forfor thethe factfact thatthat atomsatoms inin aa solidsolid arenaren’’tt independentindependent && onlyonly certaincertain frequenciesfrequencies areare possiblepossible Introduction to Cryostat Design J. G. Weisend II 11/10/2008 ICEC 2008 23 DebyeDebye TheoryTheory

„ TheThe DebyeDebye theorytheory givesgives thethe latticelattice specificspecific heatheat ofof solidssolids as:as: 3 x ⎛ ⎞ max x xeT 4 = 9RC ⎜ ⎟ dx ∫ x 2 ⎝ Θ ⎠ 0 ()e −1

„ AsAs TT ~~ 300300 KK C~C~ 3R3R ((DulongDulong Petit)Petit) 3 „ AtAt T

Introduction to Cryostat Design J. G. Weisend II 11/10/2008 ICEC 2008 24 DebyeDebye TemperaturesTemperatures

Introduction to Cryostat Design J. G. Weisend II 11/10/2008 ICEC 2008 25 ImpactImpact ofof ElectronsElectrons inin MetalsMetals onon SpecificSpecific HeatHeat

„ ThermalThermal energyenergy isis alsoalso storedstored inin thethe freefree electronselectrons inin thethe metalmetal „ QuantumQuantum theorytheory showsshows thatthat electronselectrons inin aa metalmetal cancan onlyonly havehave certaincertain wellwell defineddefined energiesenergies „ OnlyOnly aa smallsmall fractionfraction ofof thethe totaltotal electronselectrons cancan bebe excitedexcited toto higherhigher statesstates && participateparticipate inin thethe specificspecific heatheat

„ ItIt cancan bebe shownshown thatthat CCe == γγTT

Introduction to Cryostat Design J. G. Weisend II 11/10/2008 ICEC 2008 26 SpecificSpecific HeatHeat ofof SolidsSolids

„ TheThe totaltotal specificspecific heatheat ofof metalsmetals atat lowlow temperaturestemperatures maymay bebe written:written: CC == ATAT3 +BT+BT -- thethe contributioncontribution ofof thethe electronselectrons isis onlyonly importantimportant atat << 44 KK „ ParamagneticParamagnetic materialsmaterials andand otherother specialspecial materialsmaterials havehave anomalousanomalous specificspecific heatsheats -- alwaysalways doubledouble checkcheck

Introduction to Cryostat Design J. G. Weisend II 11/10/2008 ICEC 2008 27 From Cryogenic Engineering – T. Flynn (1997) Introduction to Cryostat Design J. G. Weisend II 11/10/2008 ICEC 2008 28 ThermalThermal ConductivityConductivity

„ QQ == --K(T)K(T) A(xA(x)) dt/dxdt/dx „ KK VariesVaries significantlysignificantly withwith temperaturetemperature „ TemperatureTemperature dependencedependence mustmust bebe consideredconsidered whenwhen calculatingcalculating heatheat transfertransfer ratesrates

Introduction to Cryostat Design J. G. Weisend II 11/10/2008 ICEC 2008 29 ThermalThermal ConductivityConductivity ofof MetalsMetals

„ EnergyEnergy isis transferredtransferred bothboth byby latticelattice vibrationsvibrations (phonons)(phonons) andand conductionconduction electronselectrons „ InIn ““reasonablyreasonably purepure”” metalsmetals thethe contributioncontribution ofof thethe conductionconduction electronselectrons dominatesdominates „ ThereThere areare 22 scatteringscattering mechanismsmechanisms forfor thethe conductionconduction electrons:electrons:

„ Scattering off impurities (Wo = β/T) 2 „ Scattering off phonons (Wi = αT ) „ TheThe totaltotal electronicelectronic resistivityresistivity hashas thethe formform :: 2 WWe == ααTT ++ β/β/TT

Introduction to Cryostat Design J. G. Weisend II 11/10/2008 ICEC 2008 30 ThermalThermal ConductivityConductivity ofof MetalsMetals DueDue toto ElectronsElectrons

From Low Temperature Solid State Physics –Rosenburg

„ The total electronic resistivity has the form : 2 We = αT + β/T K~ 1/We Introduction to Cryostat Design J. G. Weisend II 11/10/2008 ICEC 2008 31 HeatHeat ConductionConduction byby LatticeLattice VibrationsVibrations inin MetalsMetals

„ AnotherAnother mechanismmechanism forfor heatheat transfertransfer inin metalsmetals areare latticelattice vibrationsvibrations oror phononsphonons „ TheThe mainmain resistanceresistance toto thisthis typetype ofof heatheat transfertransfer isis scatteringscattering ofof phononsphonons offoff conductionconduction electronselectrons 2 „ ThisThis resistanceresistance isis givengiven byby WW == A/TA/T2 „ PhononPhonon heatheat transfertransfer inin metalsmetals isis generallygenerally neglectedneglected

Introduction to Cryostat Design J. G. Weisend II 11/10/2008 ICEC 2008 32 From Lakeshore Cryotronics

Introduction to Cryostat Design J. G. Weisend II 11/10/2008 ICEC 2008 33 ThermalThermal ConductivityConductivity ofof NonNon MetalsMetals

„ Insulators:Insulators: conductionconduction heatheat transfertransfer isis completelycompletely causedcaused byby latticelattice vibrationsvibrations (phonons)(phonons) „ Semiconductors:Semiconductors: conductionconduction heatheat transfertransfer isis aa mixturemixture ofof phononphonon andand electronicelectronic heatheat transfertransfer

Introduction to Cryostat Design J. G. Weisend II 11/10/2008 ICEC 2008 34 ScatteringScattering MechanismsMechanisms inin PhononPhonon HeatHeat TransferTransfer inin CrystallineCrystalline MaterialsMaterials „ Phonon/PhononPhonon/Phonon scatteringscattering ((umklappumklapp)) n „ WWu~AT~AT Exp(Exp(--θθ/gT/gT)) „ BoundaryBoundary scatteringscattering 3 „ WWB~1/T~1/T atat veryvery lowlow temperaturestemperatures „ DefectDefect scatteringscattering 3/2 „ WWD~AT~AT „ DislocationDislocation scatteringscattering 2 „ WWdis~A/T~A/T

Introduction to Cryostat Design J. G. Weisend II 11/10/2008 ICEC 2008 35 SchematicSchematic ThermalThermal ConductivityConductivity inin DielectricDielectric CrystalsCrystals

From Low Temperature Solid State Physics –Rosenburg Introduction to Cryostat Design J. G. Weisend II 11/10/2008 ICEC 2008 36 ThermalThermal ConductivityConductivity ofof AmorphousAmorphous MaterialsMaterials

„ MechanismMechanism isis latticelattice vibrationsvibrations „ ThermalThermal conductivityconductivity isis quitequite smallsmall (lack(lack ofof regularregular structure)structure) „ ThermalThermal conductivityconductivity isis proportionalproportional toto specificspecific heatheat andand thusthus decreasesdecreases withwith temperaturetemperature

Introduction to Cryostat Design J. G. Weisend II 11/10/2008 ICEC 2008 37 ThermalThermal ConductivityConductivity IntegralsIntegrals

„ TheThe strongstrong temperaturetemperature dependencedependence ofof KK makesmakes heatheat transfertransfer calculationscalculations difficultdifficult „ TheThe solutionsolution isis frequentlyfrequently toto useuse thermalthermal conductivityconductivity integralsintegrals „ TheThe heatheat conductionconduction equationequation isis writtenwritten as:as:

Q =– G ( θ2 – θ1 )

Introduction to Cryostat Design J. G. Weisend II 11/10/2008 ICEC 2008 38 ThermalThermal ConductivityConductivity IntegralsIntegrals

„ GG isis thethe geometrygeometry factorfactor

G = 1 x 2 dx A ( x ) x 1 „ θθ isis thethe thermalthermal conductivityconductivity integralintegral T i θ i = K ( T ) dT 0

Introduction to Cryostat Design J. G. Weisend II 11/10/2008 ICEC 2008 39 ThermalThermal ConductivityConductivity IntegralsIntegrals

„ Advantages:Advantages: „ SimpleSimple „ OnlyOnly endend pointpoint temperaturestemperatures areare important.important. TheThe actualactual temperaturetemperature distributiondistribution isis not.not. „ ThisThis isis quitequite usefuluseful forfor heatheat leakleak calculationscalculations

Introduction to Cryostat Design J. G. Weisend II 11/10/2008 ICEC 2008 40 From Handbook of Cryogenic Engineering, J. Weisend II (Ed)

Introduction to Cryostat Design J. G. Weisend II 11/10/2008 ICEC 2008 41 From Lakeshore Cryotronics

Introduction to Cryostat Design J. G. Weisend II 11/10/2008 ICEC 2008 42 ElectricalElectrical ResistivityResistivity

„ OhmOhm’’ss LawLaw V=IRV=IR „ R=R=ρρLL/A/A wherewhere ρρ isis thethe electricalelectrical resistivityresistivity „ ConductionConduction electronselectrons carrycarry thethe currentcurrent && therethere areare 22 scatteringscattering mechanismsmechanisms „ ScatteringScattering ofof electronselectrons offoff phononsphonons „ ScatteringScattering ofof electronselectrons offoff impuritiesimpurities oror defectsdefects (e.g.(e.g. dislocations)dislocations)

Introduction to Cryostat Design J. G. Weisend II 11/10/2008 ICEC 2008 43 ElectricalElectrical ResistivityResistivity ofof MetalsMetals

„ ForFor TT ~~ θθ phononphonon scatteringscattering dominatesdominates „ ρρ isis proportionalproportional toto TT „ ForFor T<

Introduction to Cryostat Design J. G. Weisend II 11/10/2008 ICEC 2008 44 Electrical Resistivity of Copper From Handbook of Materials for Superconducting Machinery (1974) Introduction to Cryostat Design J. G. Weisend II 11/10/2008 ICEC 2008 45 ElectricalElectrical ResistivityResistivity ofof OtherOther MaterialsMaterials

„ Amorphous materials & semiconductors have very different resistivity characteristics than metals „ The resistivity of semiconductors is very non linear & typically increases with decreasing T due to fewer electrons in the conduction band „ Superconductivity – another course

Introduction to Cryostat Design J. G. Weisend II 11/10/2008 ICEC 2008 46 WiedemannWiedemann –– FranzFranz LawLaw

„ InIn metals,metals, thethe scatteringscattering mechanismsmechanisms forfor thermalthermal && electricalelectrical conductivityconductivity areare basicallybasically thethe samesame

„ WW--FF Law:Law: K/K/σσ == LL0TT -8 2 „ LL0 isis thethe LorenzLorenz ## =2.45=2.45 x10x10 WWΩΩ/K/K „ ThisThis onlyonly worksworks atat roomroom temptemp andand TT <<<<θθ

Introduction to Cryostat Design J. G. Weisend II 11/10/2008 ICEC 2008 47 MaterialMaterial StrengthStrength

„ TendsTends toto increaseincrease atat lowlow temperaturestemperatures (as(as longlong asas therethere isis nono ductileductile toto brittlebrittle transition)transition) „ 300300 KK valuesvalues areare typicallytypically usedused forfor conservativeconservative design.design. RememberRemember allall systemssystems startstart outout atat 300300 KK && maymay unexpectedlyunexpectedly returnreturn toto 300300 K.K. „ AlwaysAlways looklook upup valuesvalues oror testtest materialsmaterials ofof interestinterest

Introduction to Cryostat Design J. G. Weisend II 11/10/2008 ICEC 2008 48 Typical Properties of 304 Stainless Steel From Cryogenic Materials Data Handbook (Revised) Schwartzberg et al ( 1970)

Introduction to Cryostat Design J. G. Weisend II 11/10/2008 ICEC 2008 49 ThermalThermal InsulationInsulation „ This is key to proper cryostat design

Thou shalt keep cold things cold

„ The effort and cost expended on this problem are driven by cryostat requirements: „ Dynamic vs. static heat loads „ Number of cryostats „ Operational lifetime & ability to refill cryostats (e.g. space systems) „ Lowest possible static heat leak isn’t always the best answer „ It is thermodynamically best to intercept heat leaks at the warmest temperature practical

Introduction to Cryostat Design J. G. Weisend II 11/10/2008 ICEC 2008 50 ThermalThermal IsolationIsolation

„ CryostatCryostat staticstatic heatheat leakleak resultsresults fromfrom convection,convection, radiationradiation andand conductionconduction heatheat transfertransfer „ ConvectionConvection heatheat transfertransfer isis stoppedstopped byby vacuumvacuum isolationisolation spacesspaces „ StandardStandard DewarDewar designdesign -6 „ 1010-6 torrtorr oror betterbetter isis bestbest forfor isolationisolation vacuumvacuum „ VacuumVacuum pressurepressure isis frequentlyfrequently muchmuch betterbetter thanthan duedue toto cryopumpingcryopumping ofof coldcold surfacesurface

Introduction to Cryostat Design J. G. Weisend II 11/10/2008 ICEC 2008 51 SuperconductingSuperconducting RFRF TestTest CryostatCryostat

ContainsContains 33 isolationisolation vacuumvacuum spacesspaces

Introduction to Cryostat Design J. G. Weisend II 11/10/2008 ICEC 2008 52 RadiationRadiation HeatHeat TransferTransfer

„ AA majormajor sourcesource ofof cryostatcryostat heatheat leakleak „ ““GreyGrey bodybody”” approximationapproximation

ε 44 q σ ( −= ) 2 TT LH

Introduction to Cryostat Design J. G. Weisend II 11/10/2008 ICEC 2008 53 „ OneOne wayway toto reducereduce heatheat leakleak isis toto selectselect lowlow emissivityemissivity materialsmaterials „ BeBe carefulcareful ofof oxidationoxidation && thethe impactimpact ofof realreal vs.vs. idealideal materialsmaterials

(From Helium Cryogenics – S. W. Van Sciver)

Introduction to Cryostat Design J. G. Weisend II 11/10/2008 ICEC 2008 54 RadiationRadiation HeatHeat TransferTransfer

„ UseUse MultilayerMultilayer InsulationInsulation (MLI)(MLI) oror ““superinsulationsuperinsulation”” insideinside thethe vacuumvacuum spacespace toto reducereduce heatheat leakleak

ε 44 q = σ ( − ) ()N + 21 TT LH

Introduction to Cryostat Design J. G. Weisend II 11/10/2008 ICEC 2008 55 MultilayerMultilayer InsulationInsulation

„ UsedUsed inin almostalmost allall cryostatscryostats „ ConsistsConsists ofof highlyhighly reflectivereflective thinthin sheetssheets withwith poorpoor thermalthermal contactcontact betweenbetween sheetssheets „ DonDon’’tt packpack MLIMLI tootoo tightly.tightly. OptimalOptimal valuevalue isis ~~ 2020 layerslayers // inchinch „ GreatGreat carecare mustmust bebe takentaken withwith seams,seams, penetrationspenetrations andand ends.ends. „ ProblemsProblems withwith thesethese cancan dominatedominate thethe heatheat leakleak

Introduction to Cryostat Design J. G. Weisend II 11/10/2008 ICEC 2008 56 MultilayerMultilayer InsulationInsulation

Introduction to Cryostat Design J. G. Weisend II 11/10/2008 ICEC 2008 57 “SERIES-PRODUCED HELIUM II CRYOSTATS FOR THE LHC MAGNETS: TECHNICAL CHOICES, INDUSTRIALISATION, COSTS” A. Poncet and V. Parma Adv. Cryo. Engr. Vol 53

Introduction to Cryostat Design J. G. Weisend II 11/10/2008 ICEC 2008 58 ConductionConduction HeatHeat LeakLeak

„ ReduceReduce conductionconduction heatheat leakleak by:by: „ Using lower conductivity materials for supports e.g. G-10 „ Increasing length and decreasing cross sectional area of connections between room temperature & cryogenic temperatures „ Reducing as much as possible amount of instrumentation wiring „ Using heat intercepts at intermediate temperatures (less heat leak to coldest temperatures)

Introduction to Cryostat Design J. G. Weisend II 11/10/2008 ICEC 2008 59 RecallRecall UseUse ofof ConductivityConductivity IntegralsIntegrals

Q =– G ( θ2 – θ1 )

Introduction to Cryostat Design J. G. Weisend II 11/10/2008 ICEC 2008 60 Introduction to Cryostat Design J. G. Weisend II 11/10/2008 ICEC 2008 61 StructuralStructural SupportsSupports

„ SolutionSolution isis highlyhighly dependentdependent onon cryostatcryostat requirementsrequirements „ ChooseChoose materialsmaterials carefullycarefully „ Acceptable for cryogenic temperatures „ Low heat leak „ DonDon’’tt overover constrainconstrain supports:supports: allowallow forfor thermalthermal contractioncontraction „ DoesDoes solutionsolution meetmeet alignmentalignment andand vibrationvibration requirements?requirements? „ MustMust alignmentalignment bebe changedchanged whilewhile cold?cold?

Introduction to Cryostat Design J. G. Weisend II 11/10/2008 ICEC 2008 62 StructuralStructural SupportSupport ExampleExample #1#1 ILCILC CryostatCryostat

support „ FRPFRP supportsupport betweenbetween 300300 KK andand CryoCryo tempstemps 2.2 K forward „ 2 K return CavityCavity assembliesassemblies tiedtied 4.5 K forward toto 300300 mmmm pipepipe 80 K return 40 K forward 300 mm backbonebackbone

„ 4.5 K return „ AllAll otherother connectionsconnections toto 300300 KK havehave flexflex cool down/ 2 K 2-phase warmup lineline oror bellowsbellows inin lineline

cavity „ MeetsMeets alignmentalignment coupler specsspecs

Introduction to Cryostat Design J. G. Weisend II 11/10/2008 ICEC 2008 63 StructuralStructural SupportSupport ExampleExample #2#2 JLabJLab 1212 GeVGeV UpgradeUpgrade CryomoduleCryomodule

„ AllAll componentscomponents areare tiedtied toto spacespace frameframe whichwhich rollsrolls intointo vacuumvacuum vesselvessel „ ConnectionsConnections toto 300300 KK donedone viavia flexflex lineslines andand bellowsbellows

Introduction to Cryostat Design J. G. Weisend II 11/10/2008 ICEC 2008 64 StructuralStructural SupportSupport ExampleExample #3#3 SimpleSimple TopTop LoadLoad CryostatCryostat

„ Very common for test cryostats „ Everything hangs from 300 K top flange „ Connections made via low conductivity piping and supports „ Everything “contracts up” „ Useful when precise alignment not an issue

Introduction to Cryostat Design J. G. Weisend II 11/10/2008 ICEC 2008 65 SafetySafety IssuesIssues

„ Warning: This is NOT a complete safety class

„ SafetySafety considerationsconsiderations shouldshould bebe designeddesigned inin fromfrom thethe beginning.beginning. RetrofitsRetrofits areare timetime consumingconsuming && expensiveexpensive

Introduction to Cryostat Design J. G. Weisend II 11/10/2008 ICEC 2008 66 OverOver PressurizationPressurization HazardsHazards

„ AA principalprincipal hazardhazard resultsresults fromfrom thethe largelarge volumevolume expansionexpansion thatthat occursoccurs whenwhen aa cryogeniccryogenic liquidliquid isis convertedconverted toto 300300 KK gasgas „ AsAs aa resultresult largelarge pressurepressure risesrises areare possiblepossible „ ThisThis couldcould easilyeasily resultresult inin materialmaterial failures,failures, andand explosiveexplosive burstingbursting

Introduction to Cryostat Design J. G. Weisend II 11/10/2008 ICEC 2008 67 ChangeChange inin volumevolume fromfrom liquidliquid atat normalnormal boilingboiling pointpoint toto gasgas atat 300300 KK andand 11 atmatm

Substance V gas/V liquid

Helium 701 Parahydrogen 788 Neon 1341 Nitrogen 646 Argon 779

CO 2 762 Oxygen 797

Introduction to Cryostat Design J. G. Weisend II 11/10/2008 ICEC 2008 68 TheThe solutionsolution isis toto alwaysalways installinstall pressurepressure reliefrelief devicesdevices

„ RedundantRedundant devicesdevices shouldshould bebe used.used. TypicallyTypically reliefrelief valvevalve ++ burstburst discdisc „ TheThe devicedevice shouldshould bebe setset toto openopen atat oror belowbelow thethe MAWPMAWP ofof thethe vesselvessel „ ValvesValves shouldshould bebe sizedsized forfor worstworst casecase scenariosscenarios „ ValvesValves shouldshould bebe testedtested && certifiedcertified beforebefore installationinstallation „ EnsureEnsure thatthat therethere areare nono trappedtrapped volumes.volumes. RememberRemember –– valvesvalves maymay leakleak oror bebe operatedoperated incorrectlyincorrectly andand cryogeniccryogenic systemssystems maymay warmwarm upup unexpectedlyunexpectedly (vacuum(vacuum spacesspaces needneed reliefrelief valvesvalves asas well)well)

Introduction to Cryostat Design J. G. Weisend II 11/10/2008 ICEC 2008 69 ReliefRelief DevicesDevices ContinuedContinued

„ Do not put shut off valves between system and relief valves „ Ask What If ? questions

Introduction to Cryostat Design J. G. Weisend II 11/10/2008 ICEC 2008 70 InstrumentationInstrumentation

„ Think about instrumentation as as a complete system – sensor, wiring feed through, DAQ rather than just the sensor itself. „ Total system cost per measuring point can be ~ $500 - $1000 „ Define requirements: „ Range „ Accuracy „ Time response „ Sensor environment (e.g. presence of magnetic or radiation fields) „ Precision – what is the smallest change detected by the sensor? „ Reliability „ Cost

Introduction to Cryostat Design J. G. Weisend II 11/10/2008 ICEC 2008 71 InstrumentationInstrumentation RulesRules ofof ThumbThumb

„ DonDon’’tt useuse moremore accuracyaccuracy && precisionprecision thanthan requiredrequired „ UseUse commerciallycommercially producedproduced sensorssensors wheneverwhenever possiblepossible –– therethere isis aa lotlot availableavailable „ WhenWhen possible,possible, mountmount sensorssensors outsideoutside cryostatcryostat (e.g.(e.g. pressurepressure transducers,transducers, flowflow meters)meters) „ ForFor criticalcritical devicesdevices insideinside ofof cryostats,cryostats, installinstall redundantredundant sensorssensors wheneverwhenever feasiblefeasible „ BeBe suresure toto considerconsider howhow toto recalibraterecalibrate sensorssensors „ OnceOnce R&DR&D isis done,done, minimizeminimize numbernumber ofof sensorssensors inin seriesseries productionproduction ofof cryostatscryostats

Introduction to Cryostat Design J. G. Weisend II 11/10/2008 ICEC 2008 72 TemperatureTemperature SensorsSensors

„ CommercialCommercial TemperatureTemperature SensingSensing OptionsOptions „ SiliconSilicon DiodesDiodes „ PtPt ResistorsResistors „ GeGe ResistorsResistors „ CarbonCarbon GlassGlass resistorsresistors „ RutheniumRuthenium OxideOxide „ CernoxCernox „ ThermocouplesThermocouples

Introduction to Cryostat Design J. G. Weisend II 11/10/2008 ICEC 2008 73 HeatHeat SinkingSinking ofof WiresWires

„ CriticalCritical toto thethe properproper useuse ofof temperaturetemperature sensorssensors inin vacuumvacuum spacesspaces „ You want to measure the temperature of the sensor not that due to heat leak down the wire „ UseUse lowlow conductivityconductivity wireswires withwith smallsmall crosscross sectionssections

Introduction to Cryostat Design J. G. Weisend II 11/10/2008 ICEC 2008 74 From “Cryogenic Instrumentation” – D.S. Holmes and S. Courts Handbook of Cryogenic Engineering

Introduction to Cryostat Design J. G. Weisend II 11/10/2008 ICEC 2008 75 PressurePressure MeasurementMeasurement

„ CarryCarry outout atat roomroom temperaturetemperature wherewhere possiblepossible (using(using aa capillarycapillary tube)tube) „ ProblemsProblems withwith roomroom temperaturetemperature pressurepressure measurementmeasurement „ ThermalThermal acousticacoustic OscillationsOscillations „ TimeTime responseresponse „ SomeSome coldcold pressurepressure transducerstransducers existexist

Introduction to Cryostat Design J. G. Weisend II 11/10/2008 ICEC 2008 76 FlowFlow MeasurementMeasurement

„ FrequentlyFrequently donedone atat roomroom temperaturetemperature

„„ StandardStandard techniquestechniques workwork „ UseUse correctcorrect materialsmaterials && calibrationcalibration „ HotHot wirewire anemometryanemometry doesndoesn’’tt workwork withwith HeHe IIII

Introduction to Cryostat Design J. G. Weisend II 11/10/2008 ICEC 2008 77 LevelLevel MeasurementMeasurement

„ SuperconductingSuperconducting levellevel gaugesgauges forfor LHeLHe serviceservice „ DifferentialDifferential pressurepressure techniquestechniques „ CapacitiveCapacitive techniquetechnique „ SelfSelf heatingheating ofof sensorssensors

„ FloatsFloats (e.g.(e.g. LNLN2))

Introduction to Cryostat Design J. G. Weisend II 11/10/2008 ICEC 2008 78 CommercialCommercial SourcesSources ofof CryogenicCryogenic InstrumentationInstrumentation

„ DonDon’’tt reinventreinvent thethe wheelwheel –– therethere isis aa lotlot alreadyalready available.available. CatalogsCatalogs cancan helphelp youyou choosechoose thethe correctcorrect sensorsensor forfor youryour applicationapplication „ TwoTwo USUS Sources:Sources:

„ Lakeshore Cryogenics http://www.lakeshore.com/

„ Scientific Instruments http://www.scientificinstruments.com/

Introduction to Cryostat Design J. G. Weisend II 11/10/2008 ICEC 2008 79 SealsSeals

„ LeaksLeaks cancan bebe avoidedavoided byby wellwell consideredconsidered designdesign choiceschoices „ Avoid the temptation to use demountable joints unless truly required „ Properly done welding is almost always the best bet „ This is particularly true for series production „ If demountable joints are required place at 300 K if at all possible „ ThereThere areare demountabledemountable sealsseals thatthat dodo workwork atat cryogeniccryogenic temperaturestemperatures „ DetailsDetails ofof useuse areare important.important. SeekSeek helphelp fromfrom vendors,vendors, referencereference booksbooks oror experiencedexperienced usersusers

Introduction to Cryostat Design J. G. Weisend II 11/10/2008 ICEC 2008 80 CryogenicCryogenic SealSeal OptionsOptions from “Cryostat Design” – G. McIntosh Handbook of Cryogenic Engineering

„ CommerciallyCommercially availableavailable ((ConFlatConFlat Flanges)Flanges)

Introduction to Cryostat Design J. G. Weisend II 11/10/2008 ICEC 2008 81 CryogenicCryogenic SealSeal OptionsOptions from “Cryostat Design” – G. McIntosh Handbook of Cryogenic Engineering

„ CommerciallyCommercially availableavailable „ GoodGood forfor pressurepressure applicationsapplications

Introduction to Cryostat Design J. G. Weisend II 11/10/2008 ICEC 2008 82 CryogenicCryogenic SealSeal OptionsOptions from “Cryostat Design” – G. McIntosh Handbook of Cryogenic Engineering

„ IndiumIndium SealSeal „ TypicallyTypically HomemadeHomemade

Introduction to Cryostat Design J. G. Weisend II 11/10/2008 ICEC 2008 83 CryogenicCryogenic SealSeal OptionsOptions from “Cryostat Design” – G. McIntosh Handbook of Cryogenic Engineering

„ MylarMylar GasketGasket „ TypicallyTypically HomemadeHomemade

Introduction to Cryostat Design J. G. Weisend II 11/10/2008 ICEC 2008 84 FeedthroughsFeedthroughs

„ InstrumentationInstrumentation feedthroughsfeedthroughs areare bestbest donedone atat 300300 KK „ AvoidAvoid cryogeniccryogenic instrumentationinstrumentation feedthroughsfeedthroughs ifif atat allall possiblepossible „ If you can’t, significant testing and validation will be needed „ InIn testtest andand prototypeprototype cryostatscryostats alwaysalways putput inin moremore feedthroughsfeedthroughs (or(or blankblank flanges)flanges) thanthan youyou thinkthink youyou’’llll needneed „ GHeGHe atat 300300 KK andand 11 barbar hashas poorpoor dielectricdielectric strengthstrength useuse spacingspacing ofof pinspins oror pottingpotting ofof feedthroughfeedthrough ifif thisthis willwill causecause problemsproblems (e.g.(e.g. inin voltagevoltage tapstaps ofof S/CS/C magnets)magnets)

Introduction to Cryostat Design J. G. Weisend II 11/10/2008 ICEC 2008 85 BayonetsBayonets

„ DemountableDemountable pipingpiping jointsjoints thatthat allowallow quickquick connectionsconnections ofof cryogeniccryogenic lineslines „ VeryVery usefuluseful inin connectingconnecting toto replaceablereplaceable cryogeniccryogenic liquidliquid suppliessupplies „ Reentrant,Reentrant, lowlow heatheat leakleak designdesign „ UsesUses atat leastleast oneone 300300 KK gasgas sealseal andand sometimessometimes aa cryogeniccryogenic liquidliquid sealseal (typically(typically Teflon)Teflon) „ MustMust bebe builtbuilt toto tighttight mechanicalmechanical tolerancestolerances „ ReceivingReceiving endend mustmust bebe lowerlower oror atat leastleast horizontalhorizontal toto deliverydelivery endend toto avoidavoid convectionconvection

Introduction to Cryostat Design J. G. Weisend II 11/10/2008 ICEC 2008 86 AirAir ForceForce StyleStyle HydrogenHydrogen BayonetBayonet

from “Cryogenic Equipment” – D. Daney Handbook of Cryogenic Engineering

Introduction to Cryostat Design J. G. Weisend II 11/10/2008 ICEC 2008 87 FNAL/SMTFFNAL/SMTF BayonetBayonet CanCan

Introduction to Cryostat Design J. G. Weisend II 11/10/2008 ICEC 2008 88 TransferTransfer LinesLines

„ VitalVital partpart ofof aa cryogeniccryogenic systemsystem „ TransfersTransfers cryogeniccryogenic fluidsfluids betweenbetween componentscomponents „ EssentiallyEssentially aa longlong cryostatcryostat „ CanCan bebe aa significantsignificant partpart ofof systemsystem costcost andand heatheat leakleak „ CanCan bebe acquiredacquired commerciallycommercially oror customcustom builtbuilt

Introduction to Cryostat Design J. G. Weisend II 11/10/2008 ICEC 2008 89 TransferTransfer LinesLines

„ KeyKey designdesign issuesissues „ ThermalThermal contractioncontraction (significant(significant duedue toto longlong lengths)lengths) „ HeatHeat LeakLeak (use(use ofof activeactive thermalthermal shields)shields) „ ForcesForces generatedgenerated byby fluidfluid pressure,pressure, thermalthermal contractioncontraction mustmust bebe managedmanaged soso asas toto notnot impactimpact alignmentalignment ofof componentscomponents „ VacuumVacuum integrityintegrity (pump(pump outsouts andand reliefrelief

valves)valves) Introduction to Cryostat Design J. G. Weisend II 11/10/2008 ICEC 2008 90 “Design, Analysis and Test Concept for Prototype Cryoline of ITER” B. Sarkar et. Al Adv. Cryo. Engr. Vol 53 (2008)

Introduction to Cryostat Design J. G. Weisend II 11/10/2008 ICEC 2008 91 TransferTransfer LinesLines

„ MethodsMethods toto addressaddress thermalthermal contractioncontraction „ RigidlyRigidly fixfix interiorinterior pipespipes toto vacuumvacuum shellshell andand installinstall bellowsbellows onon vacuumvacuum shellshell andand onon allall pipespipes „ InstallInstall bellowsbellows onon coldcold pipespipes onlyonly „ UseUse bendsbends toto allowallow interiorinterior pipespipes toto contractcontract „ UseUse InvarInvar pipespipes toto reducereduce amountamount ofof ThermalThermal contractioncontraction (CERN/LHC)(CERN/LHC)

Introduction to Cryostat Design J. G. Weisend II 11/10/2008 ICEC 2008 92 “The Local Helium Compound Transfer lines For The Large Hadron Collider Cryogenic System” C. Parente et al Adv. Cryo Engr. Vol 51 (2006) Introduction to Cryostat Design J. G. Weisend II 11/10/2008 ICEC 2008 93 „ InIn somesome cases,cases, commerciallycommercially producedproduced transfertransfer lineslines areare thethe solutionsolution „ NexansNexans flexible,flexible, multiplemultiple flowflow transfertransfer lineline http://http://www.nexans.dewww.nexans.de//

Introduction to Cryostat Design J. G. Weisend II 11/10/2008 ICEC 2008 94 ExampleExample #1:#1: LHCLHC DipoleDipole CryostatCryostat

“SERIES-PRODUCED HELIUM II CRYOSTATS FOR THE LHC MAGNETS: TECHNICAL CHOICES, INDUSTRIALISATION, COSTS” A. Poncet and V. Parma Adv. Cryo. Engr. Vol 53

„ SomeSome keykey requirementsrequirements „ 12321232 cryostatscryostats requiredrequired „ HighHigh reliabilityreliability „ 1.91.9 KK (He(He II)II) cooledcooled magnetsmagnets „ LowLow perper unitunit heatheat leakleak „ MinimizeMinimize costcost ofof materialsmaterials && assemblyassembly

Introduction to Cryostat Design J. G. Weisend II 11/10/2008 ICEC 2008 95 DesignDesign ChoicesChoices

„ VacuumVacuum vesselvessel dimensionsdimensions chosenchosen toto meetmeet industryindustry standardstandard tubetube sizessizes „ GFREGFRE supportsupport postsposts withwith heatheat interceptsintercepts atat 6060 KK andand 55 KK „ SimpleSimple integratedintegrated aluminumaluminum heatheat shieldsshields atat 6060 KK „ NoNo 55 KK radiationradiation shieldshield butbut MLIMLI blanketsblankets betweenbetween 300300 KK andand 60K60K andand betweenbetween 6060 KK andand 1.91.9 KK „ AlmostAlmost allall sealsseals areare donedone viavia weldingwelding withwith strictstrict QAQA programprogram „ MinimalMinimal instrumentationinstrumentation „ FinalFinal assemblyassembly atat CERNCERN viavia contractorcontractor

Introduction to Cryostat Design J. G. Weisend II 11/10/2008 ICEC 2008 96 “SERIES-PRODUCED HELIUM II CRYOSTATS FOR THE LHC MAGNETS: TECHNICAL CHOICES, INDUSTRIALISATION, COSTS” A. Poncet and V. Parma Adv. Cryo. Engr. Vol 53

Introduction to Cryostat Design J. G. Weisend II 11/10/2008 ICEC 2008 97 “SERIES-PRODUCED HELIUM II CRYOSTATS FOR THE LHC MAGNETS: TECHNICAL CHOICES, INDUSTRIALISATION, COSTS” A. Poncet and V. Parma Adv. Cryo. Engr. Vol 53

Introduction to Cryostat Design J. G. Weisend II 11/10/2008 ICEC 2008 98 LHCLHC DipoleDipole CryostatsCryostats

„ CostCost perper unitunit (not(not includingincluding coldcold mass)mass) ~ 100 kCHF (2007 value) Compare to 1996 estimate of 130 kCHF (2007 value) „ LargestLargest singlesingle costcost componentcomponent isis thethe vacuumvacuum vesselvessel atat 35.2%35.2% „ QAQA programprogram waswas 2.4%2.4% ofof unitunit costcost „ CurrentCurrent status:status: allall cryostatscryostats delivered,delivered, acceptedaccepted andand coldcold

Introduction to Cryostat Design J. G. Weisend II 11/10/2008 ICEC 2008 99 ExampleExample #2#2 InternationalInternational LinearLinear ColliderCollider SCRFSCRF CryomoduleCryomodule

„ TwoTwo 1515 kmkm longlong linacslinacs (250(250 GeVGeV onon 250250 GeVGeV)) „ 3535 MV/mMV/m SCRFSCRF cavitiescavities (1.3(1.3 GHz)GHz) „ RequiresRequires ~~ 20002000 cryomodulescryomodules „ ExtensionExtension ofof TESLATESLA technologytechnology „ RequirementsRequirements areare veryvery similarsimilar inin manymany waysways toto LHCLHC dipolesdipoles „ ILCILC cryomodulescryomodules havehave muchmuch higherhigher dynamicdynamic heatheat loadsloads Introduction to Cryostat Design J. G. Weisend II 11/10/2008 ICEC 2008 100 ILCILC CryomoduleCryomodule FeaturesFeatures

„ EightEight 99 cellcell scsc cavitiescavities ++ possiblypossibly 11 scsc magnetmagnet packagepackage „ ComponentsComponents areare tiedtied toto 300300 mmmm pipepipe strongbackstrongback „ 22 thermalthermal shieldsshields (40/80(40/80 KK andand 55 K)K) „ 5 K may go away during value engineering „ NewNew designdesign allowsallows semisemi--fixedfixed couplerscouplers „ DesignDesign hashas beenbeen extensivelyextensively testedtested duringduring thethe TESLATESLA projectproject „ ILCILC designdesign isis aa fourthfourth generationgeneration ofof thethe TESLATESLA cryomodulecryomodule

Introduction to Cryostat Design J. G. Weisend II 11/10/2008 ICEC 2008 101 Side View of 1st Generation TESLA Cryomodule (each end of 300 mm tube shrinks 15 mm upon cooldown)

Introduction to Cryostat Design J. G. Weisend II 11/10/2008 ICEC 2008 102 33rd GenerationGeneration TESLATESLA CryomoduleCryomodule ILCILC PrototypePrototype

support

2.2 K forward 2 K return 4.5 K forward

80 K return 40 K forward 300 mm

4.5 K return

cool down/ 2 K 2-phase warmup

cavity

coupler TESLATESLA StaticStatic HeatHeat LeakLeak MeasurementsMeasurements (note(note totaltotal 22 KK heatheat loadload isis ~~ 77 W)W)

Temperature Predicted Measured Measured Measured Level Heat Leak Heat Leak Heat Leak Heat (W) (W ) (W) Leak (W) Cryomodule Cryomodule Cryomodule #2 #1 (alone) #1 (with #2)

70 K 76.8 90 81.5 77.9 4.5 K 13.9 23 15.9 13 2 K 2.8 6 5 4

Introduction to Cryostat Design J. G. Weisend II 11/10/2008 ICEC 2008 104 AlignmentAlignment ResultsResults CryomoduleCryomodule 22 ] 0.4 0.3 mm

[ 0.2 0.1 1/11/981 1.44 0 -0.1 1/2/991.42 1 -0.2 22/3/990.40 1 -0.3 lacem ent

p -0.4 -0.5 -0.6

0123456789101112 WPM position [m] orizontal dis orizontal H

Introduction to Cryostat Design J. G. Weisend II 11/10/2008 ICEC 2008 105 ExampleExample #3#3 CryostatCryostat andand ThermalThermal ShieldShield forfor KSTARKSTAR (Korea(Korea SuperconductingSuperconducting TokamakTokamak AdvancedAdvanced Research)Research)

„ LargeLarge (~(~ 99 mm diameterdiameter TokamakTokamak usingusing superconductingsuperconducting magnets)magnets) „ S/CS/C magnetsmagnets areare containedcontained inin aa singlesingle cryostatcryostat (8.8(8.8 mm IDID andand 5.75.7 mm high)high) „ CryostatCryostat isis veryvery complexcomplex withwith 7272 penetrationspenetrations „ DesignedDesigned toto ASMEASME pressurepressure vesselvessel codecode

Introduction to Cryostat Design J. G. Weisend II 11/10/2008 ICEC 2008 106 “Development of the Cryostat Vessel for KSTAR Tokamak” N.I. Her et al, 5th Asia Plasma Fusion Association Conference Introduction to Cryostat Design J. G. Weisend II 11/10/2008 ICEC 2008 107 Cryostat Vessel Fabrication

Shell Quadrant Fabrication Pre-Assembling of Cylinder at Shop Assembling of Cylinder at Site

Fabricated Cryostat Vessel Lid & Cylinder Assemble Test KSTARKSTAR ThermalThermal ShieldShield

„ InterceptsIntercepts thermalthermal radiationradiation fromfrom 300300 KK surfacessurfaces „ ActivelyActively cooledcooled byby HeHe gasgas toto ~~ 8080 KK „ ThreeThree classesclasses ofof shieldsshields CryostatCryostat (CTS),(CTS), VacuumVacuum VesselVessel (VVTS)(VVTS) andand PortPort (PTS)(PTS) „ SpaceSpace isis veryvery limitedlimited forfor VVTSVVTS andand PTSPTS soso MLIMLI blanketsblankets areare notnot possiblepossible butbut surfacessurfaces werewere silversilver platedplated toto improveimprove emissivityemissivity

Introduction to Cryostat Design J. G. Weisend II 11/10/2008 ICEC 2008 109 PO_FT6

KSTARKSTAR ThermalThermal Shield;Shield; RecentRecent ProgressProgress

2007 IAEA

G. H. Kim, W. C. Kim, H. L. Yang, C. H. Choi, J. S. Bak (NFRC) D. K. Kang (Wonshin Eng.) PO_FT6 ThermalThermal ShieldShield LocationsLocations

Lid TS Top Vertical PTS VVTS CS Magnet TF Magnet

Median PTS Body TS Vacuum Vessel

Slanted PTS PF Magnet

Bottom Vertical Base TS PTS PO_FT6 KSTARKSTAR ThermalThermal ShieldShield

‰ KSTAR thermal shield intercepts radiation from 300 K to 4.5 K and contributes to economic operation of refrigerator system.

‰ Consists of three categories: vacuum vessel thermal shield (VVTS), port thermal shield (PTS), and cryostat thermal shield (CTS). ‰ Tube on panel configuration is a basic shape of the KSTAR TS. Shield panel @ 77 K

Cryostat wall, vacuum vessel wall Superconducting coil @ 300 K @ 4.5K

Support

qr qr Thermal radiation from 80K surface to 4.5 K Thermal radiation from 300 K surface Multi-layer Insulation or silver plating PO_FT6 VVacuumacuum VVesselessel TThermalhermal SShieldhield

‰ VVTS is toroidally segmented into 16 sectors and poloidally partitioned into 4 pieces.

‰ Shield panel is plated by silver of 10 ㎛ thickness instead of using multi-layer insulation (MLI) due to narrow gap.

‰ VVTS has redundancy cooling line. Upper Panel

Inboard Vacuum Panel Vessel Outboard Panel

TF Magnet Lower Panel Isometric view of vacuum vessel thermal shield Four sub-sectors in poloidal direction PO_FT6 CCryostatryostat TThermalhermal SShieldhield

‰ CTS is placed on the cryostat inner surface wall.

‰ MLI is adopted to prohibit thermal radiation from cryostat surface. Lid TS ‰ Each part is toroidally divided into 16 sectors.

‰ Shield panel consists of a flat stainless plate, MLI of 30 layers, 1 mm thick Body TS stainless steel sheet, and G10 spacers.

Base TS

Exploded view of cryostat thermal shield PO_FT6 PPortort TThermalhermal SShieldhield

‰ There are 72 penetration ports for connecting the vacuum vessel body Top Vertical and cryostat. PTS ‰ Ports are classified into 7 types: NBI, Slanted PTS EH, RF, SL, B&C, TV, BV port. RF PTS ‰ PTS covers all of ports. B&C PTS ‰ Silver plating method is adopted for EH PTS the PTS. ‰ All PTSs are divided into two parts: lower and upper part. NBI PTS Bottom Vertical PTS Isometric view of port thermal shields PO_FT6 MajorMajor ParametersParameters

VVTS PTS CTS

Tube on panel / Tube on panel / Tube on panel / Basic shape Silver plating Silver plating MLI

Surface area, m2 100 246 243

Total mass, ton 2.6 6.5 8.6

Number of supports 700 400 400

Length of cooling channel, m 630 850 550

Coolant Gaseous helium at 18 bars

Inlet/ Outlet Normal 55/70 55/70 55/ 70 Temperature, K Baking 55/85 55/85 55/85

Mass flow rate, Normal 43 86 86 g/ sec Baking 102 123 123

Heat load to shield, Normal 3.0 5.8 1.0 kW : Baking 7.2 15.5 1.0 KSTAR Thermal Shield; Recent Progress G.H. Kim, W.C. Kim, H.L. Yang, C.H. Choi, J.S.Bak, D.K. Kang

Introduction to Cryostat Design J. G. Weisend II 11/10/2008 ICEC 2008 117 ExampleExample #4#4 SpaceSpace CryostatCryostat TheThe XX--RayRay SpectrometerSpectrometer (XRS)(XRS)

„ MissionMission lifelife timetime isis dependentdependent onon thethe supplysupply ofof HeHe IIII (1.3(1.3 K)K) inin thethe cryostat.cryostat. InIn orderorder toto achieveachieve thethe 2.52.5 yearyear lifelife time,time, thethe heatheat leakleak mustmust bebe << 800800 μμWW „ AdditionalAdditional designdesign drivers:drivers: „ SizeSize andand weightweight „ UseUse ofof anan ADRADR requiringrequiring aa superconductingsuperconducting magnetmagnet –– sensorssensors needneed 0.0650.065 KK „ AA costlycostly oneone ofof aa kindkind devicedevice

Introduction to Cryostat Design J. G. Weisend II 11/10/2008 ICEC 2008 118 SolutionsSolutions toto MinimizeMinimize HeatHeat LeakLeak

„ AllAll heatheat leaksleaks (even(even 1010 μμWW)) areare importantimportant „ SolidSolid NeNe (17(17 K)K) dewardewar surroundssurrounds HeHe dewardewar toto reducereduce radiationradiation andand conductionconduction heatheat leakleak „ LowLow emissivityemissivity materialsmaterials used:used: polishedpolished Al,Al, goldgold platingplating andand aluminizedaluminized mylarmylar

„ HiTHiTc superconductorssuperconductors usedused forfor magnetmagnet leadsleads „ AllAll otherother wiringwiring isis optimizedoptimized forfor minimumminimum heatheat leakleak „ HeliumHelium tanktank suspendedsuspended byby graphite/epoxygraphite/epoxy strapsstraps optimizedoptimized toto meetmeet launchlaunch loadsloads „ RadiationRadiation bafflesbaffles inin ventvent andand fillfill lineslines plusplus devicesdevices toto preventprevent superfluidsuperfluid filmfilm flowflow inin ventvent lineline

Introduction to Cryostat Design J. G. Weisend II 11/10/2008 ICEC 2008 119 “Thermal Design of the XRS Helium Cryostat”, S. Breon et al., Cryogenics 36:10 (1996) Introduction to Cryostat Design J. G. Weisend II 11/10/2008 ICEC 2008 120 “Thermal Design of the XRS Helium Cryostat”, S. Breon et al., Cryogenics 36:10 (1996) Introduction to Cryostat Design J. G. Weisend II 11/10/2008 ICEC 2008 121 XRSXRS CryostatCryostat

„ AnalyticalAnalytical heatheat leakleak modelsmodels andand fullfull scalescale thermalthermal measurementsmeasurements atat thethe component,component, subsystemsubsystem andand heliumhelium insertinsert levellevel werewere carriedcarried out.out. „ MeasuredMeasured heatheat leakleak toto thethe heliumhelium insertinsert (on(on thethe ground)ground) waswas ~~ 629629 μμWW

Introduction to Cryostat Design J. G. Weisend II 11/10/2008 ICEC 2008 122 Tips for Successful Cryostat Design

„ Define requirements first

„ Design in safety from the start

„ Use appropriate materials for cryogenic temperatures

„ Review literature & learn from previous efforts

„ Use tested commercial solutions whenever possible

„ Avoid feedthroughs & demountable seals at cryogenic temperatures

„ Conduct prototype tests when required

Introduction to Cryostat Design J. G. Weisend II 11/10/2008 ICEC 2008 123 “This material was based on work supported by the National Science Foundation, while working at the Foundation.” “Any opinion, finding, and conclusions or recommendations expressed in this material; are those of the author and do not necessarily reflect the views of the National Science Foundation.” Suggestions for Additional Reading

I) Conference Proceedings

1) Advances in Cryogenic Engineering, Volumes 1 – 54, Plenum Press & AIP Press

These are the proceedings of the Cryogenic Engineering Conference / International Cryogenic Materials Conference which is held biannually (odd years) in North America.

2) Proceedings of the International Cryogenic Engineering Conference

These are the proceedings of the International Cryogenic Engineering Conference which is held biannually (even years) in Europe or Asia

3) Applied Superconductivity Conference, IEEE Transactions on Magnetics

4) Proceedings of the Magnet Technology Conference

II) Periodicals

1) Cryogenics, Elsevier Science – Monthly refereed journal covering all aspects of cryogenic engineering and science 2) Journal of Low Temperature Physics, Plenum Press – Monthly refereed journal covering fundamental aspects of cryogenics. This journal contains more physics and less engineering than Cryogenics

III) Books

1) Cryogenic Regenerative Heat Exchangers, R. Ackermann, Plenum Press, (1997) 2) Cryogenic Systems, R. Barron, Oxford University Press, (1985) 3) Cryogenic Heat Transfer, R. Barron, Taylor and Francis, (1999) 4) Cryogenic Two-Phase Flow, N.N. Filina & J. G. Weisend II, Cambridge University Press, (1996) 5) Cryogenic Engineering, T.M. Flynn, Dekker (1997) 6) Experimental Techniques for Low Temperature Measurements, J. W. Ekin, Oxford University Press, (2006) 7) Heat Transfer at Low Temperatures, W. Frost, Plenum Press (1975) 8) Technology of Liquid Helium, R. Kropschot, B. Birmingham, D. Mann, NBS Mongraph, (1968) 9) Experimental Principles & Methods Below 1 K, O. V. Lounasmaa, Academic Press (1974) 10) Low Temperature Solid State Physics – H. M. Rosenburg, Clarendon Press 11) Cryogenic Engineering, R. Scott, Met-Chem, (1963) 12) Safety in the Handling of Cryogenic Fluids, W. Stewart & F. Edeskuty, Plenum Press (1996) 13) Cryogenic Process Engineering, K. Timmerhaus & T. Flynn, Plenum Press (1989) 14) Helium Cryogenics , S. W. Van Sciver, Plenum Press (1986) 15) Cryocoolers Part I: Fundamentals, Part II: Applications, G. Walker, Plenum Press, (1983) 16) Handbook of Cryogenic Engineering, J. G. Weisend II (Ed), Taylor and Francis (1998) 17) Experimental Techniques in Low Temperature Physics, G. White, Oxford University Press (1979)

IV) Buyer’s Guides

1) Cold Facts Buyer’s Guide – Cryogenic Society of America http://www.cryogenicsociety.org/buyers_guide/ 2) Physics Today Buyer’s Guide http://www.physicstoday.org/ptbg/search.jsp