In this work, we utilize new coil objectives for stellarator optimization with autodifferentiation, including pointwise and net coil–coil forces and torques. We use these methods to perform the first large-scale optimization of planar dipole coil arrays, since arrays of small and geometrically simple coils have been proposed to partially produce the 3D magnetic fields for stellarators, generate advantageous magnetic field perturbations in tokamaks, and provide active, real-time control capabilities. We perform an ablation study to show that minimizing the orientation and location of each coil may be essential to get coil forces, coil torques, and field errors to tolerable levels. We conclude with solutions for three reactor-scale quasi-symmetric stellarators by jointly optimizing nonplanar TF coils and planar coil arrays.
This paper presents a new optimization method for designing stellarator coils that minimizes forces and torques, enabling the use of simpler and more compact coil designs. The authors demonstrate this approach on three reactor-scale stellarators, showing how it can improve the feasibility of these advanced fusion devices.