Interplay between fluctuation driven toroidal axisymmetric flows and resistive ballooning mode turbulence

Abstract

An interplay between fluctuation driven toroidal axisymmetric flows (convective cell modes) and resistive ballooning mode turbulence after the pedestal collapse is numerically studied by a four-field reduced MHD model in the BOUT++ framework. The strong flow shear suppresses the radial transport of pressure filaments, and the pressure profile in the pedestal region is partially recovered. As a result, a secondary instability is quasilinearly excited, which yields a secondary collapse. The subsequent damped oscillation is also analyzed by phase diagram analysis.