Study of second generation, high-temperature superconducting coils: determination of critical current

Min Zhang, Jae Ho Kim, Sastry Pamidi, Michal Chudy, Weijia Yuan, T. A. Coombs

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Abstract

This paper presents the modeling of second generation (2 G) high-temperature superconducting (HTS) pancake coils using finite element method. The axial symmetric model can be used to calculate current and magnetic field distribution inside the coil. The anisotropic characteristics of 2 G tapes are included in the model by direct interpolation. The model is validated by comparing to experimental results. We use the model to study critical currents of 2 G coils and find that 100μV/m is too high a criterion to determine long-term operating current of the coils, because the innermost turns of a coil will, due to the effect of local magnetic field, reach their critical current much earlier than outer turns. Our modeling shows that an average voltage criterion of 20μV/m over the coil corresponds to the point at which the innermost turns' electric field exceeds 100μV/m. So 20μV/m is suggested to be the critical current criterion of the HTS coil. The influence of background field on the coil critical current is also studied in the paper.

Original languageEnglish
Article number083902
Number of pages8
JournalJournal of Applied Physics
Volume111
Issue number8
DOIs
Publication statusPublished - 15 Apr 2012

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Keywords

  • second generation (2 G) high-temperature superconducting (HTS)
  • pancake coils
  • finite element method
  • axial symmetric model
  • magnetic field distribution
  • local magnetic field
  • electric field
  • critical current

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