摘要 |
A superconductor has a coolant passage in the internal portion to cool itself by flowing a coolant in the coolant passage. The coolant passage is formed in the stabilizing material portion in such a manner that the inner wall of the coolant passage is wave-shaped, proportion of the cross-sectional area of the coolant passage occupied in the cross-section of the superconductor is 4-22 percent, and a ratio of the circumferential length to the cross-sectional area of the coolant passage is greater 25 (cm-1). |