ABSTRACT
This chapter considers the resistive internal kink modes in a stellarator with helical windings. The first step in the theory of resistive internal kink modes in a tokamak will consist in deriving the equation for the main harmonic of perturbation in the inertial–resistive layer. The chapter provides an approach allowing one to find the equation for the main harmonic of the modes with arbitrary. Both the kink modes and the small-scale modes are described in the inertial–resistive layer by the same equation for the main harmonic. The role of toroidicity in the problem considered is essential in both the ideal and the inertial–resistive regions. Equations for kink modes in the inertial–resistive layer in toroidal geometry allowing for the effects of a high plasma pressure were derived. The chapter discusses the tearing modes in stellarators with helical windings. It shows that these modes can be unstable only in the presence of not too small a longitudinal current.
