The Design of Stellarators with Simple and Flexible Coils*

Coils are one of the main cost drivers of stellarator devices. Therefore, it is of utmost importance to shape coils that are simple enough to be economically viable, but complex enough to accurately reproduce the target magnetic fields. Typical approaches involve optimization routines that include regularization terms such as coil curvature and coil-to-coil distance.  However, such approaches keep the target magnetic field fixed. A new, state-of-the-art set of methods [1,2] has recently emerged that simplifies this by simultaneously optimizing both aspects, commonly called single-stage optimization methods. This work shows, for the first time, the broad range of applicability of such methods by generating many different configurations that have either a low number of coils, helical coils, or allow for flexible configurations that can support multiple plasma states with the same set of coils. These apply to quasisymmetric, quasi-isodynamic, or general stellarator configurations.

 

[1] R. Jorge, A. Goodman, M. Landreman, J. Rodrigues, F. Wechsung 2023. “Single-stage stellarator optimization: combining coils with fixed boundary equilibria.” Plasma Physics and Controlled Fusion 65, 074003 (2023)

 

[2] A. Giuliani 2024. “Direct Stellarator Coil Design Using Global Optimization: Application to a Comprehensive Exploration of Quasi-Axisymmetric Devices.” Journal of Plasma Physics 90(3): 905900303.