低温工学
Online ISSN : 1880-0408
Print ISSN : 0389-2441
ISSN-L : 0389-2441
研究論文
MgB2超伝導線材における常伝導部伝播現象の定量的評価
船木 和夫久保 輝朗中尾 彰浩佐藤 誠樹松尾 政晃柁川 一弘田中 和英岡田 道哉熊倉 浩明林 秀美
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2008 年 43 巻 10 号 p. 423-429

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As a thermal property of MgB2 wires, we observed the propagation velocity of a normal zone for those immersed in liquid helium. The normal zone propagation was initiated by a resistive heater and the propagation velocity was estimated from the response of voltage difference between potential taps attached to the wire in a transverse magnetic field. The specimen was a mono-filamentary bare wire with a composite sheath of iron and copper. A part of the wire was cooled directly by liquid helium and the other was covered with a vacuum-grease layer for thermal insulation. The propagation velocity observed in each part was of a very low level in comparison with typical ones for usual NbTi wires, which may come from the high critical temperature and the low overall current density. We numerically calculate the propagation velocity with transient cooling models and discuss the normal zone propagation in relation to the cooling processes. We also evaluated the propagation of the normal zone in the MgB2 wires with advanced transport properties, which were attained in short specimens, under the condition of conduction cooling in a wide range of operation temperatures.

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© 2008 公益社団法人 低温工学・超電導学会 (旧 社団法人 低温工学協会)
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