Abstract Almost all present High Temperature Superconducting (HTS) cable designs for magnets are based on twisted or transposed concepts that were developed for Low Temperature Superconducting (LTS) cables. However, requirements for LTS materials (like filament twisting) are in general not valid for HTS materials, which are extremely stable; for example, non-twisted multifilamentary Bi-2223 tapes have been successfully used in several magnets. Is twisting necessary for HTS cables? We investigated inductance mismatches and AC losses by numerical and analytical methods in twisted and non-twisted stacks of coated conductors; various experiments reported in the literature support the analysis. Large (hysteretic) losses are common in all magnets built with tapes and are far larger than in magnets built with LTS multifilamentary conductors, because of the aspect ratio and large width of the tape. In small magnets, losses and residual magnetisation could be reduced by replacing a wide tape with a non-twisted stack of narrow tapes. In large cables, we have found that twisting a stack of tapes reduces losses only marginally. Therefore, non-twisted stack cables could be designed to have losses comparable to those of twisted ones. Some examples of non-twisted large cables for fusion applications are discussed: non-twisted stack designs can be simpler, more robust and cost effective than twisted ones, but would require additional R&D.

中文翻译：

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用于磁体的非扭曲涂层导体叠层：电感和交流损耗分析

摘要 目前，几乎所有用于磁铁的高温超导 (HTS) 电缆设计都基于为低温超导 (LTS) 电缆开发的绞合或转置概念。但是，对 LTS 材料的要求（如细丝扭曲）通常不适用于极其稳定的 HTS 材料；例如，无捻复丝 Bi-2223 胶带已成功用于多种磁体。HTS 电缆需要扭绞吗？我们通过数值和分析方法研究了带涂层导体的绞合和非绞合叠层的电感失配和交流损耗；文献中报道的各种实验支持了这一分析。大（磁滞）损耗在所有用胶带制成的磁铁中都很常见，并且远远大于用 LTS 多丝导体制成的磁铁，因为胶带的纵横比和大宽度。在小磁铁中，可以通过用非扭曲的窄带堆叠代替宽带来减少损耗和剩余磁化强度。在大型电缆中，我们发现绞合一叠胶带只能略微降低损耗。因此，可以将非双绞堆叠电缆设计为具有与双绞电缆相当的损耗。讨论了一些用于融合应用的非扭绞大电缆的例子：非扭绞堆叠设计比双绞设计更简单、更坚固且更具成本效益，但需要额外的研发。我们发现扭转一叠磁带只能略微减少损失。因此，可以将非双绞堆叠电缆设计为具有与双绞电缆相当的损耗。讨论了一些用于融合应用的非扭绞大电缆的例子：非扭绞堆叠设计比双绞设计更简单、更坚固且更具成本效益，但需要额外的研发。我们发现扭转一叠磁带只能略微减少损失。因此，可以将非双绞堆叠电缆设计为具有与双绞电缆相当的损耗。讨论了一些用于融合应用的非扭绞大电缆的例子：非扭绞堆叠设计比双绞设计更简单、更坚固且更具成本效益，但需要额外的研发。