Finding less complicated coils that have adequately low field errors is a crucial step in stellarator development. One coil metric that is of high importance is the maximum curvature of the coil centreline, or coil single filament. Conductors cannot be bent below some threshold minimum radius of curvature. High coil curvatures can cause strains to exceed acceptable levels, especially in superconducting coils. We investigate three ways to optimize coil curvature and find that applying penalty functions to the coil curvature solves for coils that have a constrained maximum curvature and low field error. Penalty functions are implemented in FOCUS and coil solutions optimized for an HSX-like ‘plasma boundary’ are presented.

中文翻译：

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使用 FOCUS 进行约束仿星器线圈曲率优化

寻找具有足够低场误差的不太复杂的线圈是仿星器开发的关键步骤。一个非常重要的线圈度量是线圈中心线或线圈单灯丝的最大曲率。导体不能弯曲到低于某个阈值最小曲率半径。高线圈曲率会导致应变超过可接受的水平，尤其是在超导线圈中。我们研究了优化线圈曲率的三种方法，并发现将惩罚函数应用于线圈曲率可以解决最大曲率受限且场误差低的线圈。FOCUS 中实现了惩罚功能，并提出了针对类似 HSX 的“等离子边界”优化的线圈解决方案。