Two-fluid electromagnetic instability in a self-consistent inhomogeneous plasma with saturated magnetic shear

Abstract

The stability of an inhomogeneous finite-β plasma confined by a sheared magnetic field is analysed in the two-fluid slab approximation. The stationary plasma involves an electron plasma current that is self-consistently generated by magnetic shear through Ampère's law. Magnetic shear is found to be stabilizing (destabilizing) if the electron drift consistent with it is antiparallel (parallel) to the propagation direction of drift waves. Mode stability arises from competition between the Doppler shifts resulting from both the electron diamagnetic drift and the electron drift related to magnetic shear, and the wave frequency. The finite-β effects reduce the growth rate but do not stabilize the mode. In contrast with the hydromagnetic tearing instabilities, the growth rate is proportional to the electron-ion collision frequency, which is regarded as the lowest-order term in powers of the electron-ion collision frequency by Taylor's theorem.