Propagation of hydromagnetic waves through an anisotropic plasma

Abstract

The propagation of small amplitude hydromagnetic waves of a collisionless, anisotropic plasma in a strong magnetic field is treated using the Chew—Goldberger—Low (CGL) fluid equations. The Alfvén, fast and slow magnetoacoustic, and entropy modes are analysed by phase speed and wave front diagrams and compared to their counterparts in magnetohydrodynamics (MHD) where collisions maintain an isotropic pressure. Two main classes of CGL waves are identified, pseudo-MHD and reverse-MHD where the latter has the slow wave speed greater than the Alfvén wave speed. Significant differences of the CGL hydromagnetic waves as compared to MHD waves are found which have special relevance for a study of infinitesimal and finite discontinuities in space plasmas.