Kink–ballooning mode in circular tokamak plasma

Peeling–ballooning modes, which are driven by gradients of parallel current and pressure in the pedestal, are widely accepted as the instability triggering large Edge Localized Modes (ELMs). However, the current-driven mode related to ELMs is not fully understood. This paper is about comparing the kink mode to the peeling mode, and the modified current profiles are specifically made to be simultaneously kink stable/peeling unstable or vice versa so that the two modes (or the modes coupled to peeling modes) can be compared. Caltrans-Corsica is used to generate a series of equilibria with modified edge current profiles. Based on these equilibria, the effects of edge current density on plasma instabilities are studied with the three-field BOUT++ elm-pb code. The results suggest that kink–ballooning modes can drive ELMs in some peeling-stable regions. Compared to the peeling–ballooning mode, kink–ballooning modes have comparatively lower poloidal resonant modes and growth rates at low toroidal mode numbers.