Effect of Thermal Cycles on Critical Current and AC Loss for Superconducting Coils Having Positive or Negative Thermal Expansion Bobbin
Effect of Thermal Cycles on Critical Current and AC Loss for Superconducting Coils Having Positive or Negative Thermal Expansion Bobbin
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热循环对具有正热膨胀或负热膨胀骨架的超导线圈的临界电流和交流损耗的影响
DOI：
10.1109/tasc.2008.920586
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发表时间：
2008
影响因子：
1.8
通讯作者：
A. Yamanaka
中科院分区：
文献类型：
--
作者：
T. Takao;K. Yamamoto;Y. Yamada;Y. Nakajima;K. Nakamura;M. Arikawa;S. Fukui;A. Nishimura;A. Yamanaka
我们研究了室温和液氮温度之间的热循环对两个超导线圈的临界电流（Ic）和交流损耗的影响：一个是在从室温到低温冷却过程中膨胀的线轴，另一个是在冷却过程中收缩的线轴。100次循环后，两个线轴均未发生降解。收缩线轴线圈的Ic没有降低，而膨胀线轴线圈的Ic由于重复的热应变而降低。膨胀线圈的AC损耗在第一个循环时明显小于收缩线圈的损耗;然而，它随着热循环而增加，并最终超过收缩线圈的损耗，因为膨胀线圈的Ic由于热疲劳而降低。这些结果表明，线轴尺寸的适度膨胀有效地降低了AC损耗，而过度膨胀降低了Ic并增加了AC损耗。
We investigated the effect of thermal cycles between room and liquid-nitrogen temperatures on the critical current (Ic) and AC loss of two superconducting coils: one with a bobbin that expands during cooling from room temperature to cryogenic temperature and one with a bobbin that contracts during the cooling. After 100 cycles, neither bobbin suffered degradation. The Ic of the contraction-bobbin coil did not decrease, and that of the expansion-bobbin coil decreased due to the repeated thermal strain. The expansion coil's AC loss was significantly smaller than the contraction coil's loss at the first cycle; however, it increased with the thermal cycles and eventually surpassed the contraction coil's loss because the Ic of the expansion coil decreased due to the thermal fatigue. These results indicate that a moderate expansion in the size of the bobbin effectively decreases AC loss and that excessive expansion reduces the Ic and increases the AC loss.