Compressional effects on drift-resistive instabil-ities in general toroidal plasma

Abstract

The drift-resistive modes in general toroidal geometry are studied analytically and numerically. The study includes the effects from ion acoustic couplings, ion polarization drift, and perpendicular resistivity. These effects can completely stabilize the drift resistive modes. The perpendicular resistivity is effective in stabilizing mainly the drift interchange modes, while the ion acoustic couplings are dominant mechanism for the stabilization of the drift tearing modes. From the ion-polarization drift effects of the perpendicular compression, the critical value of magnetic energy $\Delta c$ saturates for a moderate diamagnetic drift frequency region. The favorable average curvature is a stabilizing factor for the drift tearing modes with the criterion of $\Delta``<\Delta c$ but an instability from unfavorable curvature even with $\Delta``< 0$ exists in the semi-collisional region.