Viscosity effects on waves in partially and fully ionized plasma in magnetic field

TL;DR

This paper investigates how viscosity influences Alfven and Langmuir waves in the solar atmosphere, providing detailed coefficients and analyzing their effects across different altitudes and conditions.

Contribution

It presents a comprehensive set of viscosity coefficients for electrons, protons, and hydrogen atoms in partially and fully ionized plasma, applied to solar atmospheric layers.

Findings

Viscosity is negligible for Alfven waves in the chromosphere.

In the corona, viscosity affects Alfven waves only at very short wavelengths.

Viscosity is the dominant damping mechanism for Langmuir waves in the corona.

Abstract

Viscosity is discussed in multicomponent partially and fully ionized plasma, and its effects on two very different waves (Alfven and Langmuir) in solar atmosphere. A full set of viscosity coefficients is presented which includes coefficients for electrons, protons and hydrogen atoms. These are applied to layers with mostly magnetized protons in solar chromosphere where the Alfven wave could in principle be expected. The viscosity coefficients are calculated and presented graphically for the altitudes between 700 and 2200 km, and required corresponding cross sections for various types of collisions are given in terms of altitude. It is shown that in chromosphere the viscosity plays no role for the Alfven wave, which is only strongly affected by ion friction with neutrals. In corona, assuming the magnetic field of a few Gauss, the Alfven wave is more affected by ion viscosity than by ion-electron friction only for wavelengths shorter that 1-30 km, dependent on parameters and assuming the perturbed magnetic field of one percent of its equilibrium value. For the Langmuir wave the viscosity-friction interplay in chromosphere is shown to be dependent on altitude and on wavelengths. In corona the viscosity is the main dissipative mechanism acting on the Langmuir mode.