H i g h T e H m IGH p e r a T t EMPERATURE u r e S u S UPERCONDUCTOR p e r c o A n CCELERATOR d u c t o M AGNETS r A c c e l e r a t o 2 14 r 6- 1 0 2 S- M I ES a H16 g T0 N-/2 n R11 e CE10/ ts JvN 2016 Jeroen van Nugteren H T S IGH EMPERATURE UPERCONDUCTOR A M CCELERATOR AGNETS Jeroen van Nugteren November10,2016 PhDGraduationCommittee: Chairman : prof. dr. ir. J.W.M.Hilgenkamp UniversityofTwente PhDsupervisor : prof. dr. ir. H.H.J.tenKate UniversityofTwente Co-supervisors : dr. G.deRijk CERN dr. M.M.J.Dhallé UniversityofTwente Members : prof. dr. ir. H.J.M.terBrake UniversityofTwente prof. dr. ir. A.H.vandenBoogaard UniversityofTwente prof. dr. L.Rossi UniversityofMilan prof. dr. J.J.Engelen UniversityofAmsterdam prof. dr. D.C.Larbalestier FloridaStateUniversity dr. J.A.A.J.Perenboom RadboudUniversity Theresearchdescribedinthisthesiswascarriedoutat: CERN,Geneva,Switzerland, TechnologyDepartment(TE), Magnets,SuperconductorsandCryostatsGroup(MSC), SuperconductingMagnetDesignandTechnologySection(MDT). HighTemperatureSuperconductorAcceleratorMagnets JeroenvanNugteren PhDthesis,UniversityofTwente,TheNetherlands ISBN:978-94-028-0403-4 Printedby: IpskampPrinting Coverby: JeroenvanNugterenandNikkieDeelen c JeroenvanNugteren,Enschede,2016. (cid:13) H T S IGH EMPERATURE UPERCONDUCTOR A M CCELERATOR AGNETS DISSERTATION toobtain thedegreeofdoctorattheUniversityofTwente, ontheauthorityoftherectormagnificus, prof.dr.H.Brinksma, onaccountofthedecisionofthegraduationcommittee, tobepubliclydefended onThursdayNovember10,2016at16:45 by Jeroen van Nugteren bornonOctober23,1986 atUbbergen,TheNetherlands ThisthesishasbeenapprovedbythePhDsupervisor: prof.dr.ir.H.H.J.tenKate A BSTRACT For future particle accelerators bending dipoles are considered with magnetic fields exceeding 20T. This can only be achieved using high temperature superconductors (HTS).Theseexhibitdifferentpropertiesfromclassicallowtemperaturesuperconduc- torsandstillrequiresignificantresearchanddevelopmentbeforetheycanbeapplied inapracticalacceleratormagnet. InordertostudyHTSindetail,afiveteslademonstratormagnetnamedFeather-M2is designedandconstructed. ThemagnetisbasedonReBCOcoatedconductor,whichis assembledintoa10kAclassRoebelcable. AnewandoptimizedAlignedBlocklayout isused,whichtakesadvantageoftheanisotropyoftheconductor. Thisisachievedby providing local alignment of the Roebel cable in the coil windings with the magnetic fieldlines. A new Network Model capable of analyzing transient electro-magnetic and thermal phenomena in coated conductor cables and coils is developed. This model is neces- sary to solve critical issues in coated conductor accelerator magnets, such as thermal stability,quenchpropagationandfieldquality. TheelectricalpartoftheNetworkModelisvalidatedusingaseriesofbenchmarksim- ulationtestsandmeasurements. Themodelisthenusedtocalculatethedynamicfield qualityincoilstructures. Itisconcludedthatdynamiccompensationofthefieldqual- ityisneeded. Thiscanbeachievedbyaseriesofpersistentcurrentshimcoilsthatare insertedinsidetheaperture,whichisanovelconceptintroducedinthisthesis. The thermal part of the Network Model is validated by comparing it to an earlier ex- perimentallyvalidatedone-dimensionalsingletapemodel. Usingthisaquenchismod- eledinasectionofRoebelcableandlaterinthefullFeather-M2coil. Itisshownthat the initialization of the quench consists of three phases: Thermal Drift, Pre-Quench andQuench. TheDriftphasecanbedetectedusingtemperaturesensorsandthePre- Quench phase using an array of pick-up coils. These quench detection techniques, provided sufficient margin is maintained, could allow for safe operation of HTS coils uptoveryhighcurrentdensities. Aniterativelayoutoptimizationalgorithmisimplementedandusedtostudylayoutsat themagneticfieldlimitofNb Sn. ItisshownthatgradingoftheNb Snisessentialfor 3 3 reachingmagneticfieldsbeyond14Twith20%marginandthatoperationat1.9Kand improvingthecriticalcurrentdensityoftheNb Snconductorarehighlyrecommended. 3 Additionally,preliminaryresultsareshownforlayoutsusingHTSinthehighmagnetic fieldregionofthecoilin20Tmagnets. i ii