Error Correction Techniques and Analysis for the Princeton Permanent Magnet Stellarator

Stellarators offer a promising path towards fusion reactors, but their design and construction are complicated by stringent tolerance requirements on highly complex 3D coils.  A potential way to simplify the engineering requirements for stellarators is to use simple planar toroidal field coils along with permanent magnet arrays to generate shaping fields.  In order to ensure sufficient field accuracy while minimizing engineering complexity and system cost, new techniques are required to correct the field produced by the permanent magnet arrays to within requirements set by plasma physics. Attention is given to minimizing those errors that are important to the formation of islands, rather than enforcing strict global engineering tolerances. This work describes a novel correction method developed for this purpose.  This method will be applied to the design and construction of a 1/2 period of the National Compact Stellarator Experiment (NCSX) equilibrium using permanent magnet arrays. Analysis techniques and initial results using the method for error correction on the proposed permanent magnet stellarator are presented.