Investigation of non-uniform current distribution and establishment of desigin guideline for large current capacity in Y-base superconducting coil

我们分析和实验评估的电流分布在环形线圈的串联连接的双饼线圈组成的堆叠导体与并联连接的多个YBCO带材和环形线圈组成的并联连接的多个双饼线圈组成的单个YBCO带材导体串联连接。在此基础上，分析了环形线圈中电流分布不均匀的原因，并提出了大容量YBCO环形线圈的设计原则。由于带之间的距离非常小，由于带厚度的制造误差，每个带中的自感的差异容易导致堆叠导体中的不均匀电流分布。因此，由单个带状导体构成的并联连接的多个双饼形线圈对于防止不均匀的电流分布是有效的。

We analytically and experimentally evaluated the current distributions in a toroidal coil composed of the series connected double pancake coils composed of a stacked conductor with parallel-connected multiple YBCO tapes and a toroidal coil composed of the parallel-connected multiple double pancake coils composed of single YBCO tape conductor connected in series. Based on these results, we investigated the cause of non-uniform current distribution in the toroidal coils and the desigin guideline for an YBCO toroidal coil with large current capacity. Due to quite small distance between the tapes, the non-uniform current distribution in the stacked conductor is easily occurred by the difference of the self-inductance in each tape due to a manufacturing error of tape thickness. Therefore, the parallel-connected multiple double pancake coils composed of single tape conductor is effective for preventing the non-uniform current distribution.