Equilibrium and stability of stellarators

Very little is known about stellarator equilibrium and stability. Of the three main approaches now available to answer these questions, the stellarator expansion provides the greatest simplification. An equilibrium code and a stability code that incorporate the stellarator expansion are developed. The equilibrium code uses an Eulerian grid and can be used to study free-boundary equilibria. The stability code uses flux coordinates and employs a Lagrangian formulation suitable for the investigation of the normal modes of the plasma. This code can be used to study the stability of both free-boundary and fixed-boundary modes. Application is made to existing devices, modular coil stellarators, a proposed device (ATF), and a tokamak-torsatron hybrid