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Cold Magnetic Shield Update Niklas Templeton 29/06/15

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Text of Cold Magnetic Shield Update Niklas Templeton 29/06/15

LHC Crab Cavity UK meeting

Cold Magnetic Shield UpdateNiklas Templeton29/06/15Updated OPERA Analysis by Kiril MarinovSpecification: 4mm all round cavity clearance revised fasteningall external branch-tube coversiso front-top viewRevised DQW Cold Shieldiso back-bottom view

minimised gapscombined connectorshelium transfer holes3mm on 50mm spacing22cm2

Revised RFD Cold Shieldiso front-top viewhelium transfer holes3mm on 50mm spacing27cm2incorporated dummy beampipecombined connectors

Revised RFD Cold Shieldiso back-bottom viewbeampipe branch-tube coverminimised gaps>4mm all round cavity clearance revised size & geometry - helium vessel rev. CConcerns over the complexity of RFD shield difficult assembly could lead to shield becoming misshapen, stressed/damaged.Suggested by Akira Yamamoto (KEK) due to the complexity of the welded helium vesselOriginal reasons for internal shield:Minimise number of penetrationsTighter shield gives greater performanceAvoid complexity of external helium vessel geometry (no longer valid)Protected from random damageMinimal impact other dressed cavity systemsEnsure low operating temperature for best shield performance

However, the helium vessel external geometry is now more simple, should we reconsider a more traditional approach, at least for the RFD option?

Internal Shield Evaluationinitial internal shield for thin walled vesselRFD external shield concept

2 folded shell panels top and bottomadditional strips connect panels and cover any gaps

RFD external shield conceptbranch-tube covers addedbranch-tube covers clear flange and choke ports to minimise heightcryoline cover added after weldingRFD external shield concept

connection slots aide alignment & reduce thermal stressesiso front-top viewprovisional suspension rod coversprovisional intercavity support covers (for quotation purposes)cuts for flange survey featuresconnection to helium vessel and thermalisation to be detailedPrevious RFD Concept

Alternatively, we could reconsider and develop the thin walled options, should an appropriate vessel fabrication solution be found. Concept ComparisonRFD InternalClose fitting for greater performanceMinimise size & number of penetrationsIndependent from other dressed cavity systemsProtected from random damage during installation

Difficult to access after helium vessel assemblyMaintenance, inspection, testingComplexityIncreased assembly timeRisk of assembly error & damageRFD ExternalGreater branch tube attenuationHOM ShieldingSimplicityNo risk of impacting cavity coolingEase of inspection, maintenance, testing

Additional penetrations for cryoline and support systemsRisk of random damage during installation & commissioningDependence on readiness of other dressed cavity systems

Other considerationsNo. panels & componentsStiffnessCurvatureOverall sizeDesign continuitySupport flexibilityThermalisationCleanliness

Manufacture operations Cuts, holes, folds, bends, weldsSurvey & alignment mountsDesign modificationsLHC compatibilityHandling & toolingWeighted Decision Matrix

External Shield Concept

Internal Shield ConceptScoringCriteria Performance0Poor1Below Average2Average3Good4ExcellentCriteriaDescriptionWeighting (/100)Score (0 - 4)Weighted ScoreInternal ExternalInternal ExternalPerformanceAccording to specification3044120120IndependenceMinimal impact and reliance on other systems20316020Ease of AssemblyMinimal assembly time, tooling, risk of assembly damage10131030AccessFor inspection, maintenance & adaptation1003030ProtectionMinimal risk of random damage10313010CostComparison quote from Magnetic Shields LTD20----ReadinessFor tender & procurement-31--100220210TOTAL SCORE (/400):ConclusionDQW design has been improved and refinedThe result is a simple and effective internal shield which is ready for procurement

RFD shield has also been developed and improved while alternative options have been explored due to unavoidable complexity and associated risk of internal shield designMany advantages & disadvantages when comparing internal and external RFD shield. Weighted Decision Matrix shows no clear preferenceDecision may come down to readiness & dependence on other dressed cavity systems

Currently waiting on budget costing quotes from Magnetic Shields LTD

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