Stabilization of drift waves by a non-uniform high-frequency field

Abstract

The paper considers the interaction of a high-frequency electromagnetic field with a magnetized inhomogene-ous plasma. From kinetic and Maxwellian equations a system of equations is obtained which describes the linear oscillations of an inhomogeneous plasma. The dispersion relation is given for the potential oscillations. The results are obtained for the limiting case of long waves k⊥ρΛ→0. Three types of drift instability are considered: (a) electronic drift instability; (b) slow ion-acoustic waves, and(c) drift-temperature instability.It is shown that, by applying an h.f. field having a certain frequency and intensity it is possible to enlarge the region of stability against drift oscillations in an inhomogeneous magnetized plasma.When an h.f. field is applied, the stability region for a fast ion-acoustic wave grows considerably in the direction of negative values of ηe. Stabilization occurs as a result of the increased oscillation frequency which accompanies the application of the h.f. field, and this in turn intensifies Landau damping by the electrons.The stabilizing effect of the h.f. field pressure is associated with a Doppler shift resulting from plasma particle drift with velocity g/ωHα (g is the effective ‘acceleration due to gravity’ with allowance for the potential forces in a non-perturbed state). The sign of the growth rate of the slow ion-acoustic wave does not change when the h. f. field is applied, but its value decreases considerably. The h.f. magnetic field stabilizes the drift-temperature instability for negative values of ηi.