Analytical Theory of Flux Coordinates for Stellarators

Effective method is proposed to construct the flux coordinates for toroidal plasma equilibrium con-figurations. This method is applied to conventional stellarators. Three kinds of flux coordinates are con-sidered: coordinates with a fixed toroidal angle, Hamada and Boozer coordinates. Keywords: plasma equilibrium, flux/magnetic coordinates, conventional stellarator 1. lntroduction Flux (or magnetic) coordinates are defined as cur-vilinear coordinates (a, x2, x3) with a: consl describ-ing toroidal magnetic surfaces, and x2 and x3 as the an-gular coordinates on these surfaces. For general theory see [1,2]. Three special kinds of flux coordinates became se-lected in a practice: coordinates with a fixed toroidal angle [3, 4], Hamada [5] and Boozer [6] coordinates