Extended representation for ballooning modes in the presence of shear flows

Abstract

Previous representations of toroidal eigenmodes in the presence of shear flows are pointed out to give rise to a secular time behaviour for perturbations with sufficiently small perpendicular wavelengths. The purpose of this paper is to present an extended ballooning representation, properly accounting for the effects of strong toroidal rotation as well as of differential rotation and correcting such a deficiency. The basic feature of the perturbation is that it exactly satisfies all the dynamical constraints and, in particular, it is periodic in time with a global period (i.e., independent of position).