Experiments on the Effects of Local Normal Transitions in Multi-Stacked No-Insulation REBCO Pancake Coils

Tetsuri Ichikawa*, Yuta Kakimoto, Haruka Onoshita, Tetsuro Kinpara, So Noguchi, Shigeo Nagaya, Tomonori Watanabe, Atsushi Ishiyama

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

3 Citations (Scopus)


No-insulation (NI) coils are an important technique for high-field magnetic resonance imaging (MRI). One of the technical issues with NI coils is their thermal and electromagnetic behavior when a local normal transition occurs. Given that multiple stacked coils are used in MRI, the interaction between coils must also be investigated, because a local normal transition may affect the other NI coils through magnetic coupling. In fact, when a local normal transition occurs, there is a possibility that large electromagnetic forces are applied to the other coils, or quench may be induced in some of them. Even though overcurrent tests of stacked NI coils have been conducted, the results are not helpful in actual MRI operation. In this study, we investigate the effects of the occurrence of a local normal transition in multi-stacked NI coil systems under conditions similar to those of actual operation, with a constant transport current below the coil's Ic. The occurrence of a local normal transition is simulated by applying current to a heater inserted in manufactured small NI double pancake coils. To evaluate the interaction between NI coils, the voltage and changes in the generated magnetic field are measured at each coil. We also show the current distribution in the coils, as obtained by the partial element equivalent circuit method. The obtained results allow us to evaluate the interaction of the NI coils and evaluate coil protection methods.

Original languageEnglish
Article number8653863
JournalIEEE Transactions on Applied Superconductivity
Issue number5
Publication statusPublished - 2019 Aug


  • Coil protection
  • HTS coil
  • high-field MRI
  • local normal transition
  • multi-stacked no-insulation coil
  • partial element equivalent circuit (PEEC) model

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Electrical and Electronic Engineering


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