EFFECT OF FINITE ION LARMOR RADIUS ON THE STABILITY OF SUPERPOSED FLUIDS

Abstract

The effect of finite ion Larmor radius on the problem of stability of incompressible and infinitely conducting superposed fluids is investigated for a general direction of perturbation. It is found that whereas the interchange perturbations are stabilized in the presence of Larmor radius, the noninterchange perturbations (which affect the ambient magnetic field) lead to overstability due to Larmor radius effects in a configuration (unstable in the absence of magnetic field) stabilized by a strong enough magnetic field. The configuration which is monotonically unstable in the absence of Larmor radius now, in addition, exhibits overstable modes. Similar conclusions are obtained in the presence of vortex sheet as well.