ABSTRACT
This chapter discusses the inertialess perturbations described by the dispersion relation. It also discusses that the magnetic drift of particles plays an important role in all the kinds of perturbations. In this connection, the relevant instabilities are called the magneto-drift instabilities. The analysis of inertialess perturbations shows that for a Maxwellian velocity distribution, they grow in time only if there is a temperature gradient in addition to the density gradient. The theory of instabilities in an inhomogeneous finite–β plasma is widely used for the interpretation of collective processes in space plasma. The magneto-drift resonance between transverse drift waves and electrons is possible in the presence of an electron temperature gradient. Then both a stabilization of these waves and their additional destabilization can take place. The point of special consideration was clarification of the hydrodynamic meaning of Tserkovnikov's waves.
