Effects of inelastic collisions on Alfvén waves in partially ionized plasmas

Abstract

Based on a three-component description of partially ionized plasmas (i.e., electrons, ions, and neutral atoms), effects of inelastic collisions between ions (neutrals) and electrons on Alfv,n waves (AWs) in a partially ionized plasma are studied. It is shown that for a fixed ionizability () or a fixed inelastic collision parameter (chi, i.e., the ratio of the inelastic to elastic collision frequency), the damping rate of AWs has a peak value round k (z) v (A)/nu (in) 1, where k (z) is the parallel wavenumber of AWs, v (A) is the Alfv,n velocity, and nu (in) is the elastic collision frequency between ions and neutrals. On the other hand, the damping rate of AWs decreases monotonously with the ionizability for a fixed inelastic collision parameter, but has a peak value when the inelastic collision parameter varies for sufficiently small ionizability (). For sufficiently large ionizability (), it is found that the damping rate decreases with the inelastic collision parameter. The results may help us to understand the physics of AWs in partially ionized plasmas.