Study of stellarator devices by expansion techniques

Expansion techniques have led to new tools for designing stellarators and interpreting experimental results. The stellarator expansion is coupled with Hamiltonian techniques to investigate the effect of plasma pressure on magnetic surface structure. An expansion for nonplanar-axis systems is described. A reduced-equation initial-value formalism is used to create three-dimensional heliac equilibria. A low-..beta.. expansion with an auxiliary expansion about the magnetic axis makes possible the determination of island widths in heliacs and allows analytic determination of the effect of equilibrium modifications associated with plasma pressure on radial transport.