Iterative Optimization of Auxiliary Coils for Stellarators

Abstract

A direct method is described for finding optimal coils, and 'flexibility' coils are presented which have been determined by this method. The method proceeds straight to a coil design from the required vacuum magnetic configuration parameters for the desired plasma, rather than producing an intermediate 'surface current' description. This allows engineering requirements to be faithfully reproduced. The method has been applied by implementing a perturbative vacuum rotational transform evaluator as an optimality criterion. The speed of this evaluation step allows a thorough exploration of the set of possible coil trajectories and permits a high degree of confidence in the optimality of the best candidate. It is shown that the flexible heliac winding is very near optimal for rotational transform generation. Show more