Three electrostatic temperature drift instabilities

Abstract

This paper considers temperature drift instabilities, modes which can be driven unstable solely by a temperature gradient perpendicular to a magnetic field. The linear electrostatic dispersion relation for a Vlasov plasma in a uniform magnetic field is used and propagation is assumed to be in the plane perpendicular to the gradient. Three temperature drift instabilities have been found. The ion temperature drift instability arises at frequencies much below the ion cyclotron frequency, the electron temperature drift instability propagates somewhat below that frequency and the lower-hybrid temperature drift instability has frequencies above the lower-hybrid frequency. The first of these modes is driven by an ion temperature gradient and is enhanced by increasing Te/Ti. The latter two modes are driven by an electron temperature gradient and are enhanced by a decreasing Te/Ti. Density gradients are considered as an additional source of free energy, and comparisons of temperature drift with density drift instabilities are made.