Design of Optimal Structure of AC Superconducting Wire Using 3-D Finite Element Method

提出了一种分析交流超导导线中三维磁场的新方法。通过将计算值与实测值进行比较，对交流超导导线耦合损耗计算方法进行了验证。研究结果还表明，采用新开发的数值方法可以研究超导导线的最佳结构。所得结果可总结如下：1。交流超导导线中三维磁场分析方法的研究进展本文提出了一种有效考虑电导率各向异性的多丝超导电缆三维耦合电流分析新方法。三维分析的前后处理器由于多丝交流超导导线是绞合的，三维网格比较复杂。在此基础上，开发了一种高效的交流超导导线三维网格生成图形系统。交流损耗的测量制作了交流超导磁体（60Hz），采用拾取线圈法测量了耦合损耗。用双频法验证了交流损耗可分为滞后损耗和耦合损耗。将测量的耦合损耗与计算值进行了比较，结果表明，耦合损耗受线间接触电阻的影响很大。研究了交流超导导线的结构和基体结构对耦合损耗的影响。结果表明，利用本研究提出的新方法，交流超导导线的优化设计是可能的。

A new method for analyzing 3-D magnetic fields in ac superconducting wires has been developed. The verification of the method for calculating the coupling loss of ac superconducting wire is carried out by comparing the calculated values with measured ones. It is also shown that the opotimal structure of the superconducting wire can be investigated by using the newly developed numerical method. The results obtained can be summarized as follows :1. Development for analyzing 3-D Magnetic Fields in AC Superconducting WiresA new method for analyzing 3-D coupling current in multifilamentary superconducting cable is developed taking efficiently into account the anisotropy of conductivity.2. Pre- and Post-Processors for 3-D AnalysisAs the multifilamentary ac superconducting wire is twisted, ita 3-D mesh is complicated. Then, an efficient graphic system for producing 3-D meshes of ac superconducting wire is developed.3. Measurement of AC LossesThe ac superconducting magnet (60Hz) is produced, and the coupling loss is measured by using the pick-up coil method. It is verified that the ac losscan be divided into hysteresis loss and coupling loss using the two frequency method. The measured coupling loss is compared with the calculated value, and it is shown that the coupling loss is very much affected by the contact resistance between the strands.4. Optimal Structure of AC Superconducting WireThe effects of thestructure of cable and the matrix (CuNi) on coupling losses are investigated. It is shown that the potimal design of ac superconducting wire is possible by using new method developed in this research.