Investigation of Current-sharing properties of parallel conductors composed of REBa2Cu3Oy superconducting tapes for NMR
Investigation of Current-sharing properties of parallel conductors composed of REBa2Cu3Oy superconducting tapes for NMR
复制标题
REBa2Cu3Oy超导带构成的核磁共振平行导体均流特性研究
DOI：
10.1109/tasc.2019.2895900
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发表时间：
2019
影响因子：
1.8
通讯作者：
Izumi Teruo
中科院分区：
文献类型：
--
作者：
Sagawa Shintaro;Miura Shun;Iwakuma Masataka;Fukumoto Yusuke;Yoshida Kohichi;Sato Seiki;Izumi Teruo
对于缠绕有REBa 2Cu 3 Oy（REBCO，其中RE =稀土元素如Y、Gd、Eu等）超导带的核磁共振超导磁体，从磁体保护的观点来看，需要提高带的电流容量。因此，提出了引入平行导体的配置。组成的磁带应该绝缘和换位低交流损耗和均匀的电流分配之间的磁带。然而，当带具有不同的临界电流Ic值和它们的n值时，带将不具有均匀的传输电流。本文从理论上研究了由REBCO带绕成线圈的三股平行导体的均流特性，并考虑了磁场的空间分布，即，Ic的磁场和场角依赖性。这里，假设I-V特性由n值模型表示。推导了等效电路方程并进行了数值求解。结果，揭示了在高于0.01Hz的频率下，即使在带之间Ic和n值存在10%的变化，电流流动也几乎均匀。另一方面，在直流的情况下，电流共享取决于Ic和n值的分散。本文提出了一种控制股线间端子接触电阻的简单方法。
For nuclear magnetic resonance superconducting magnets wound with REBa2Cu3Oy(REBCO, where RE = rare earth elements such as Y, Gd, Eu, and so on) superconducting tapes, the current capacity of the tapes needs to be enhanced from the viewpoint of magnet protection. Thus, the introduction of the configuration of parallel conductors was proposed. The constituent tapes should be insulated and transposed for low ac loss and uniform current sharing among the tapes. However, when the tapes have different values of critical current, Ic, and their n-values, the tapes will not have uniform transport currents. In this paper, the current-sharing properties of three-strand parallel conductors composed of REBCO tapes, which were wound into coils, were theoretically investigated by accounting for the spatial distribution of the magnetic field, i.e., magnetic field and field angular dependences of Ic. Here, it was assumed that the I-V characteristics are expressed by the n-value model. Equivalent circuit equations were derived and numerically solved. As a result, it was revealed that at a frequency higher than 0.01 Hz, the current flow is almost uniform even if there is a variation of 10% in Ic and the n-value among the tapes. On the other hand, in the case of dc, the current sharing depends on the dispersion of Ic and the n-value. In this paper, a simple solution for the control of the contact resistance at the terminals among the strands was proposed.