A Study on Stability Criterion for Cryocooler Operating HTS Coils

냉동기운전 고온초전도코일의 안전성평가기준에 관한 연구

  • 석산돈사 (와세다대 전기전자정보공학과) ;
  • 김석범 (서울대 전기·컴퓨터공학부) ;
  • 한경희 (명지대 전기정보제어공학부)
  • Published : 2001.07.01

Abstract

We investigated the stability of cryocooler-cooled high-temperature superconducting (HTS) coils by using a computer program based on FEM. In this study, the current at which "thermal runaway" occurs, which depends on the relationship between the cooling power of the cryocooler and the heat generation in HTS coils, was adopted as a stability criterion of cryocooler operating HTS coils. It was shown that cryocooler-cooled HTS coil was stable in operating current above the critical current from the numerical analysis results by HTS model coil. And also, if we efficiently remove the heat generation from HTS coils by potimizing heat drain, the ramp-rate limitation can be mitigated because the effect of AC loss by the current rise was too small. Furthermore, in the case of pulsed operation; the HTS model coil is ramped from zero to the peak value in one second and back to zero current in one second, such as the operation of SMES device, the peak value of poerating current is 1.5-2 times greater than that of the thermal runaway current.

Keywords

HTS coils;GM cryocooler;FEM analysis;stability criterion;thermal runaway current

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