A new numerical method for designing the external coils of a stellarator is presented. In this method, the shape of filamentary coils is expressed using fully three-dimensional B-spline curves that are not necessarily constrained on a winding surface. The control points of B-spline curves are optimized together with the coil position and current to minimize an objective function, which is defined using normal field components and engineering constraints. The genetic algorithm is employed to minimize the objective function for arbitrary combinations of modular, helical, and circular poloidal field coils without giving any specific initial guess of coil shapes. A new numerical code genetic optimizer using sequence of points for external coil is developed on the basis of this method, and successfully found optimized modular coils for the stellarators CFQS and Wendelstein 7-X. We also found a specific pattern of helical coil arrangement that can reproduce these optimized stellarators while creating divertor legs outside of the closed magnetic surfaces.

提出了一种设计仿星器外部线圈的新数值方法。在这种方法中，灯丝线圈的形状使用完全三维的 B 样条曲线表示，这些曲线不一定限制在绕组表面上。B 样条曲线的控制点与线圈位置和电流一起优化，以最小化目标函数，目标函数是使用法向场分量和工程约束定义的。遗传算法用于最小化模块化、螺旋和圆形极向场线圈的任意组合的目标函数，而无需给出线圈形状的任何特定初始猜测。在该方法的基础上开发了一种新的外线圈点序列数字编码遗传优化器，并成功地为仿星器 CFQS 和 Wendelstein 7-X 找到了优化的模块化线圈。我们还发现了一种特定的螺旋线圈排列模式，它可以复制这些优化的仿星器，同时在封闭的磁性表面之外创建偏滤器腿。