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Investigation of the ac loss properties of superconducting parallel conductors

超导平行导体交流损耗特性的研究

基本信息

批准号：
12650283
负责人：
IWAKUMA Masataka
金额：
$ 2.3万
依托单位：
Kyushu University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2000
资助国家：
日本
起止时间：
2000 至 2002
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-12650283/
关键词：
Oxide superconductor Parallel conductor Transposition Ac loss Current distribution Superconducting transformer

项目摘要

We overthrew the conventional theory for the formation of superconductors with low-Tc superconducting wires and proposed that the configuration of transposed parallel conductors is the most suitable for oxide superconducting wires. In this paper, we investigated the ac loss properties of superconducting parallel conductors. We first introduced the basic equation of magnetic field on the supposition that a 2-strand parallel conductor composed of superconducting multifilamentary wires with a rectangular cross section which are transposed only once, is exposed to a uniform magnetic field. By solving it, we deduced the theoretical expressions of the additional ac losses due the formation of parallel conductors. We also studied the applicability of superconducting parallel conductors to pancake-coils and solenoidal coils. The obtained conclusion is as follows.1) In the case that the strands are transposed at the optimum position and the interlinkage magnetic flux is cancelled out, the shielding current is not induced. The additional ac loss is produced in case that the transposition deviates from the optimum condition.2) In the case that the induced shielding current is less than the critical current of a strand, Ic, the additional ac loss is proportional to the square of field amplitude, Bm^2, and the square of the deviation length, Δ1^2, and has a debye-type frequency dependence.3) In the case that the induced shielding current reaches Ic, the additional ac loss is proportional to Bm and Δ1 and has no frequency dependence.4) The optimum transposition in the coils which are wound with 2- to 4-strand parallel conductors were clarified.We concluded that ac losses in superconducting parallel conductors in the usual situation are so small that the ac loss density is nearly equal to that in the constituent strands. The availability of superconducting parallel conductors was verified.

我们推翻了用低Tc超导导线形成超导体的传统理论，提出了换位平行导体结构是最适合氧化物超导导线的结构。本文研究了超导平行导体的交流损耗特性。本文首先介绍了磁场的基本方程，假定由矩形截面的超导多芯线组成的两股平行导体在均匀磁场中只换位一次。通过求解该方程，我们推导出了并联导体附加交流损耗的理论表达式。我们还研究了超导平行导体对扁平线圈和螺线管线圈的适用性。得到的结论是：1）在最佳位置换位，消除交链磁通时，不产生屏蔽电流。2）在屏蔽感应电流小于股线临界电流Ic的情况下，附加交流损耗与磁场幅值的平方Bm^2和偏移长度的平方Δ1^2成正比，并且具有德拜型频率依赖性。3）在感应屏蔽电流达到Ic的情况下，附加交流损耗与Bm和Δ1成正比，与频率无关。4）在2- 4-μ m绕制的线圈中，最佳换位阐明了超导平行线的交流损耗密度，得出了超导平行线在通常情况下的交流损耗很小，其交流损耗密度几乎等于组成超导平行线的交流损耗密度的结论。验证了超导并联导体的可行性。