Influence of ion-ion collisions and kinetic effects on minidisruptions of confined plasmas

Abstract

Resistive m=1 modes associated with minidisruptions of current carrying plasmas are shown to be strongly influenced simultaneously by the effects of finite ion gyroradius, finite drift wave frequency, and ion-ion collisions in the plasma regimes of interest. The modes acquire finite frequency of oscillation and, for low β, the reduction in their growth rates is due mainly to the drift wave frequency, the effect of ion-ion collisions being slight (less than 10% effect); but, even for low β, ion-ion collisions significantly alter the radial structure of the modes. As a result, the reconnecting mode, which tends to lose its radial localization above a threshold temperature, remains well-localized when ion-ion collisions are included.

Moment equations treatment of the reconnecting mode

“…Moreover, the mode acquires a frequency of oscillation with a phase velocity about equal that of the electron drift wave. As we have indicated briefly, the ion-ion collisions, which are important in the still higher temperature regimes, reduce the growth rate of the mode further [8]. Thus we can expect that magnetically confined plasmas with higher electron temperatures than those realized so far will be considerably less affected by the onset of this mode.…”

“…The detailed analysis of these effects is reported in Ref. [8]. and TR = 47JTO/T7||C 2 is a typical resistive diffusion time.…”

“…The stability analysis of the reconnecting mode including the collisional viscosity effect is reported in Ref. [8].…”

“…The theory of this resistive internal kink mode, as developed in Ref. [6], has been extended subsequently in Refs [7,8] to include "kinetic" effects such as finite ion gyroradius, finite electron drift wave frequency and ion-ion collisions, which are important in high-density and high-electrontemperature regimes of thermonuclear interest.…”