ABSTRACT
This chapter considers a plasma moving along the magnetic field with a velocity U dependent on the transverse coordinate x. It discusses large-scale and small-scale varieties of the instabilities. The chapter presents the theory of drift magnetoacoustic Kelvin–Helmholtz (kh) instabilities. It demonstrates the transition from the ordinaryinstability to the drift-Alfven instability. In the case of small-scale perturbations, the physical reason for the ordinary kh instability, that is, the electromagnetic interaction between regions of different velocities, disappears. The notion of the ordinary kh instability can be obtained in the simplest manner by considering a plasma with a step-function velocity profile. In contrast to the ordinary kh instability, the drift-Alfven kh instabilities, both large-scale and small-scale, may be considered as microinstabilities. The Alfven microinstabilities are sensitive to the ion-pressure gradient which leads to their suppression. The density gradient in the problem of drift magnetoacoustickhinstabilities is taken into account by dispersion relation.
