Radial electric field effect on resistive interchange modes

Shear flow, driven by the radial electric field, has a stabilizing effect on the resistive interchange (or g) mode destabilized by the unfavorable curvature in a heliotron/torsatron. The following conditions are required: (i) kyv0>γgLE/Δ and (ii) Δ<LE, where the flow velocity profile is assumed to be v0 tanh(x/LE), ky is a wave number in the poloidal direction, γg is a growth rate at v0=0, and Δ is a radial mode width at v0=0. The origin x=0 corresponds to a mode resonant surface. When v0 is sufficiently large, the usual Kelvin–Helmholtz instability appears.