Thermal instability of a compressible finite Larmor radius, Hall plasma in porous medium

Abstract

The thermal instability of a compressible plasma in porous medium is considered in the presence of a uniform horizontal magnetic field to include the Hall current and finite Larmor radius effects. The Hall current and finite Larmor radius (FLR), individually, have destabilizing and stabilizing effects, respectively, on the system. In the simultaneous presence of both, there is a competition between the destabilizing role of Hall current and stabilizing role of FLR and each—Hall current and FLR—succeeds in stabilizing a certain wave-number range. In the absence of magnetic field (and hence absence of Hall current and FLR), the destabilizing effect of medium permeability is depicted but in the presence of magnetic field (and hence presence of Hall current and FLR), the medium permeability may have a stabilizing or destabilizing effect on thermal instability of the plasma. In contrast to the case of vertical magnetic field (and corresponding Hall current and FLR), the oscillatory modes are not allowed for, (cpβ/g)≳1, in the case of horizontal magnetic field (and corresponding Hall current and FLR). The effect of compressibility is found to postpone the onset of thermal instability in plasma.