MHD waves in the partially ionized plasma: from single to multi-fluid approach

TL;DR

This paper reviews the properties and equations of MHD waves in partially ionized solar plasmas, comparing single-fluid and multi-fluid models and analyzing wave behavior under various physical effects.

Contribution

It provides a comprehensive comparison of single-fluid and multi-fluid approaches to MHD waves in partially ionized plasmas, including effects of collisions and non-linearities.

Findings

Ambipolar diffusion affects wave propagation and dissipation.

Elastic collisions influence wave damping in multi-fluid models.

Gravitational stratification impacts wave behavior.

Abstract

This Chapter outlines the basic properties of waves in solar partially ionized plasmas. It provides a summary of the main sets of equations, from the single-fluid formalism, to the multi-fluid one, giving examples for purely hydrogen, and for hydrogen-helium plasmas. It then discusses the solutions for waves under the single-fluid frame: the influence of the ambipolar diffusion, diamagnetic effect, and the Hall effect on the propagation, dissipation, and mode conversion of the magnetohydrodynamic waves. The Chapter continues by outlining the wave solutions in the multi-fluid formalism: the influence of the elastic inter-particle collisions into the propagation, damping and dissipation of different magnetohydrodynamic modes. Both parts discuss linear and non-linear wave solutions, and the effects of the gravitational stratification of the solar atmosphere.