Bounce Time Averaged Wave Potential and the Dissipative Trapped Ion Instability

Abstract

Effect of banana orbit of the trapped particle on the dissipative trapped ion instability (DTII) is investigated. As the frequency of the DTII is much smaller than the bounce frequency, wave potential is averaged over the bounce period or along the banana orbit of the trapped particle. With this averaged wave potential, dispersion relation is obtained including the effect of the banana orbit. Stabilizing effect is not so large as expected. The growth rate is positive for the wide range of the poloidal mode number m. Previous results, based on the growth rate which makes use of an analogy to the finite Larmor radius effect, overestimate the damping by the effect of the banana orbit incorrectly.