STABILITY OF ALFVEN WINGS IN HMHD

Abstract

A conducting source moving uniformly through a magnetized plasma generates, among a variety of perturbations, Alfvén waves. Alfvén waves can build up structures in the plasma called Alfvén wings. The wings have been detected and measured in many solar system bodies, and their existence have been theoretically proved also. Under certain conditions, Hall and electronic pressure must be taken into account in the Ohm’s law and so one gets Hall Magnetohydrodynamics (HMHD). In spite of Sallago and Platzeck have shown the existence of Alfvén wings in HMHD, their stability under such conditions remains to be studied. The aim of this paper is to analyze the stability of an Alfvén wing, in the presence of an incompressible perturbation that has the same symmetry than the structure and polarization, in HMHD. Palumbo has developed an analytical method for the study of the stability of static structures with a symmetry in magnetized plasmas, in the presence of incompressible perturbations with the same symmetry than the structure. Since Alfvén wings are stationary structures, Sallago and Platzeck have shown the stability of such Alfvén wings in MHD conditions by extending Palumbo’s method. In the present paper this method is extended for Alfvén wings in HMHD conditions, and one concludes that in the presence of this kind of perturbations they are stable.