DYNAMIC STABILIZATION OF DRIFT WAVES IN A COLLISJONLESS PLASMA BY a.c. ELECTRIC FIELDS

摘要

The influence of an a.c. electric field parallel to the confining magnetic field on low frequency instabilities in an inhomogeneous collisionless low β plasma has been considered, A general dispersion relation has been derived, valid for small amplitudes of the time varying field, for frequencies of mo¬dulation and plasma mode frequencies much smaller than the ion cyclotron frequency. The formalism has been applied to a variety of drift instabilities and the flute instability in a maxwellian plasma. Possibilities of dynamic stabilization have been found for the majority of the drift waves. Corresponding stability cri¬teria in terms of the electric field amplitude and conditions on the modulation frequency are given.