Maximizing Stellarator Coil Tolerances by Minimizing Island Sensitivity

Stellarator equilibria are subject to islands and chaos due to the lack of a geometrical symmetry in their magnetic field structures. We quantify an island's sensitivity by sampling variations of an island's width due to coil set perturbations. Coil tolerances are shown to increase as we minimize island sensitivity. We have demonstrated that stellarator coil tolerances can be relaxed significantly through optimization thus enabling lower cost and lower risk development paths of the stellarator concept.