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1991 Fiscal Year Final Research Report Summary

Study on Improvement of Stability of Superconductors by Active Control

Research Project

Project/Area Number 02452123
Research Category

Grant-in-Aid for General Scientific Research (B)

Allocation TypeSingle-year Grants
Research Field Thermal engineering
Research InstitutionUniversity of Tokyo

Principal Investigator

NISHIO Shigefumi  University of Tokyo, Institute of Industrial Science, Associate Professor, 生産技術研究所, 助教授 (00111568)

Project Period (FY) 1990 – 1991
KeywordsSuperconductors / Superconducting Magnets / Stabilization / Active Control / Electric Field / Critical Heat Flux
Research Abstract

At present, good understanding of heat transfer of cryogenic liquids is needed to prepare for advent of superconducting magnets made of high Tc superconducting materials. In this research, first, boiling heat transfer of coolant in natural-convection cooling-channels in superconducting magnets was investigated experimentally for liquid nitrogen. As the result, an equation correlating critical heat flux (CHF) to the channel gap was derived, and it was shown that the equation predicted correctly the critical heat flux in rectangular, circular, and annular channels for both liquid nitrogen and helium. Second, as a base of the critical-current margin design criterion proposed by lwasa, a model predicting the take-off conditions of conductor temperature was developed, and it was shown that the model can predict correctly the take-off conditions for liquid helium and water. Coupling this model with the CHF correlation derived in the research, it became possible to predict approximately the take-off condition in cooling channels. Finally, to enhance the critical heat flux in a cooling channel, the effect of electric field applied between the channel walls was investigated. The results showed that the critical heat flux was increased by applying electric field between the channel walls. Based on the results stated above, a novel method to improve the stability of current-carrying superconductors was proposed. In the method, it was proposed that to suppress normal-zone propagation, heat transfer of coolant adjacent to normal zone was enhanced by imposing an electric field locally between the conductor and an electrode if the normal transition was detected by acoustic emission. The method proposed in the study is considered to be superior to conventional methods of stabilization, because this method makes possible to decrease the copper ratio.

  • Research Products

    (4 results)

All Other

All Publications (4 results)

  • [Publications] 西尾 茂文,永井 二郎: "浸漬冷却型超電導導体の温度テイクオフ条件" 低温工学. 27. (1992)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] Shigefumi Nishio and Niroh Nagai: "A Model Predicting Temperatare Take-Off Conditions of Superconductors" Cryogenics. 32. (1992)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] Nishio, S. and Nagai, N.: ""Take-Off Conditions of Superconductors Cooled in Liquid Coolant"" Cryogenic Engineering. 27. 37-42 (1992)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] Nishio, S. and Nagai, N.: ""A Model Predicting Temperature Take-Off Conditions of Superconductors"" Cryogenics. 32. (1992)

    • Description
      「研究成果報告書概要(欧文)」より

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Published: 1993-03-16  

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