Electrostatic temperature gradient drift instabilities

Abstract

The linear Vlasov dispersion relation for electrostatic instabilities driven by a cross-field current due to density and temperature gradients in a unidirectional magnetic field is examined in the local approximation. Both electrons and ions are taken as magnetized, and propagation is in the plane defined by the drift velocities and the magnetic field. The effects of temperature gradients on three different instabilities are studied and compared. Electron (ion) temperature gradients parallel (antiparallel) to the density gradient enhance the maximum growth rate of the universal drift instability; but, an antiparallel ∇T for either species is necessary to enhance the growth of the lower hybrid drift or to lower the threshold of the ion cyclotron ion drift instability. Oblique propagation of the ion cyclotron ion drift instability corresponds to lower thresholds than at perpendicular propagation.