Stabilization of the Alfvén-ion cyclotron instability in inhomogeneous media

Abstract

Stabilization criteria for the Alfvén-ion cyclotron instability due to anisotropic temperature in inhomogeneous high β plasmas are obtained. A wave equation is derived appropriate to describe the essential aspects of this fluid-type instability in inhomogeneous media. The dispersion relation is obtained with the help of the associated Legendre functions. The critical β for stabilization is a sharply increasing function of the inhomogeneity strength of the system: the critical system length Lc is approximately proportional to β−1/2. Under the equilibrium configuration the stability criteria for the mirror mode instability and the present mode are compared, and it is found that those for the mirror mode are more stringent for moderate to large β.