P2-1685Superconducting Joint betweenHigh-temperature Superconducting WiresKey Words: High magnetic field, superconducting magnet, energy-saving systemSuperconducting (SC) magnets are widely used for various applications. To improve magnet performance and achieve energy-saving magnet systems, R&D of high-temperature superconductor (HTS) has progressed. Recently, significant progress on SC joint technology for HTS has been made to realize HTS magnets operated in persistent current mode.⚫R&D of SC joint for HTS wires has progressed.⚫Low joint resistance is evaluated at NIMS.⚫HTS model can explain joint characteristics.ConclusionToward HTS persistent mode magnetsEvaluation of HTS joints⚫Evaluate microstructure vs. joint characteristics⚫Establish on-site joint fabrication & evaluation method⚫Develop full-scale persistent-mode HTS magnetFuture PlanIntroductionOur motivation is to contribute to facilitating development of full-scale & energy-saving persistent-mode HTS magnets. To achieve this, we have addressed the issues on HTS joint & persistent current through materials research, such as how to establish a reliable HTS joining method, what determines the HTS joint characteristics, and so on.Theme underDiscussionSuperconducting System Group, GREEN Yasuaki TakedaE-mail：： TAKEDA.Yasuaki@nims.go.jpK. Kobayashi et al., IEEE TAS(2020).SC magnetCryocoolerIloop: Loop currentL: Self-inductanceJoint resistance (Rj)evaluation system:suitable for measuring current decay using a closed-loop sampleTime dependence ofIloopwas measured.SCjointPowersupplyFieldCurrentPersistent currentUsualTakeda et al., APEX12(2019) 023003. Takeda et al., SuST35(2022) 02LT02. NMRResearch magnetPPMS®Ref: NIMS Open FacilityHigh-fieldfacilities@SakurasiteJoint~800°CLoopWe kept loop atRT in HT forjoint.𝐼𝐼loop𝑡𝑡=𝐼𝐼loop0𝑒𝑒−𝑅𝑅j𝐿𝐿𝑡𝑡Conventional HTS model can explain HTS joint resistance characteristicsHigh temperature superconducting (HTS) wirePersistent current mode SC magnetSC joint for Bi-based HTS wiresBi-based wire(Bi,Pb)2Sr2Ca2Cu3OySumitomoElectricIndustries, Ltd.Rare earth (RE)-based wireREBa2Cu3OyFujikura Ltd.Flux creep modelThermally activated flux quantum can movew/ voltage generation.Consider“flux creep”Measurableresistance:10–7–10–16Takeda et al., APEX16(2023) 093002.-Temporally stable- Energy-saving-Used for mostof commercialMRI & NMR0.3°HTS layerSynthesized intermediate layerExposingHTS layerby low-anglepolishingAgCross sectional viewHTS filaments
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