Coil optimization methods for a planar coil stellarator

• Published in: Nuclear fusion Vol. 65; no. 2; pp. 26051 - 26064
• Main Authors: Kruger, T.G., Martin, M.F., Gates, D.A.
• Format: Journal Article
• Language: English
• Published: IOP Publishing 01.02.2025
• Subjects: coil optimization; planar coil stellarator; planar coils; stellarators; Thea energy
• ISSN: 0029-5515; 1741-4326
• DOI: 10.1088/1741-4326/ada56b

The planar coil stellarator design is a novel approach to producing the confining magnetic field of a stellarator plasma. The work presented here details the optimization of the two types of planar coils that are used in the planar coil design: the plasma encircling coils, and the shaping coils. The plasma encircling coils provide the mean magnetic field and linking current, similar to the toroidal field (TF) coils in a tokamak. The plasma encircling coils can be rotationally symmetric TF-like coils and produce a B ∝ 1 / R field, but optimizing their placement, tilt, and shaping can substantially reduce the magnetic field error. In addition, an array of dipole-like shaping coils, that lie on a surface between the plasma boundary and the encircling coils, correct for the residual magnetic field error following encircling coil optimization. As a proof-of-concept, it is shown that by optimizing both types of coils, subject to realistic engineering constraints, reasonable magnetic field errors of ∼1% have been achieved. Comparison to a traditional modular coil set reveals that similarly low magnetic field errors can be attained with the planar coil stellarator.