用于降低洛伦兹力的电磁线圈优化
Electromagnetic coil optimization for reduced Lorentz forces
AI总结：
本文在SIMSOPT软件中利用自动微分实现了一种高效且精确的电磁线圈自力简化模型，用于准轴对称stellarator的线圈优化，在显著降低线圈洛伦兹力的同时，分析了其对快粒子损失和线圈-等离子体距离的权衡影响。
摘要：
降低电磁线圈上的磁力是高场设备（如 stellarator 或 tokamak）设计中的一个重要考量。然而，在优化循环中，通过常规有限元建模来评估这些力可能过于耗时。尽管通过将大孔径线圈近似为无限薄可以快速计算互力，但这种近似对于自力并不成立，因为它会导致非物理的发散。最近，一种基于丝状模型的电磁线圈自场、自力和自感的新型简化模型被严格推导出来，并证明其具有高精度和数值计算高效性。在本文中，我们展示了在 SIMSOPT stellarator 设计软件中采用自动微分实现该简化自力模型的方法，并将其用于准轴对称 stellarator 的基于导数的线圈优化中。我们表明，可以显著降低整个线圈上的逐点力，但这会以快粒子损失和线圈与等离子体表面之间的最小距离的权衡为代价。磁力与线圈-表面距离之间的权衡由位于等离子体“豆形”截面内侧附近线圈的线圈间最小距离所调节。力与快粒子损失之间的关系由法向场误差调节。线圈力可以降低到某一阈值，同时对损失的恶化降至最低。重要的是，此处的磁体优化方法也可用于 tokamak、其他聚变概念以及聚变之外的应用。
英文摘要：
The reduction of magnetic forces on electromagnetic coils is an important consideration in the design of high-field devices such as the stellarator or tokamak. Unfortunately, these forces may be too time-consuming to evaluate by conventional finite element modeling within an optimization loop. Although mutual forces can be computed rapidly by approximating large-bore coils as infinitely thin, this approximation does not hold for self-forces as it leads to an unphysical divergence. Recently, a novel reduced model for the self-field, self-force, and self-inductance of electromagnetic coils based on filamentary models was rigorously derived and demonstrated to be highly accurate and numerically efficient to evaluate. In this paper, we present an implementation of the reduced self-force model employing automatic differentiation within the SIMSOPT stellarator design software and use it in derivative-based coil optimization for a quasi-axisymmetric stellarator. We show that it is possible to significantly reduce point-wise forces throughout the coils, though this comes with trade-offs to fast particle losses and the minimum distance between coils and the plasma surface. The trade-off between magnetic forces and coil-surface distance is mediated by the minimum coil-coil distance for coils near the inboard side of the "bean" cross-section of the plasma. The relationship between forces and fast particle losses is mediated by the normal field error. Coil forces can be lowered to a threshold with minimal deterioration to losses. Importantly, the magnet optimization approach here can be used also for tokamaks, other fusion concepts, and applications outside of fusion.
机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。
