Optimization of the Planar Coil Stellarator

Thea Energy, Inc. is advancing the planar coil stellarator which leverages a system of flat superconducting magnets to create magnetic fields. This work details the optimization of two planar coil types: encircling coils and shaping coils. Encircling coils link the plasma's axis to provide net toroidal flux. Shaping coils are relatively small and placed into arrays. Encircling coils are optimized to generate the majority of an equilibrium's magnetic field and then an array of shaping coils is added to shape the magnetic field locally. The shaping coil array is roughly located on a surface, just outside the tritium breeding blankets and neutron shields. Thea Energy's planar coil design allows large sectors of the shaping coil array to be removed between the encircling coils for maintenance. Both sets of coils can be wound in tension as they are planar and convex. In this work, we demonstrate that fusion-relevant magnetic fields are achievable by optimizing both coil types, subject to realistic engineering constraints. New ideas for optimizing advantageous divertors for quasi-axisymmetric plasmas will also be presented and discussed.