On the Theory of Bulk Viscosity of Cold Plasmas and Thermodynamics of Alkali-Noble Gas Cocktails

TL;DR

This paper derives an explicit expression for bulk viscosity in cold plasmas, showing it can vastly exceed shear viscosity, and explores thermodynamics of alkali-noble gas mixtures with potential solar and laboratory applications.

Contribution

It provides a new explicit formula for bulk viscosity in cold plasmas and systematizes thermodynamic relations for alkali-noble gas cocktails, with implications for solar and laboratory plasmas.

Findings

Bulk viscosity can be orders of magnitude larger than shear viscosity.

Mandelstam-Leontovich approximation is effectively exact for cold plasmas.

Explicit thermodynamic formulas for alkali-noble cocktails are developed.

Abstract

Solving the kinetic equation for ionization-recombination processes in cold plasmas for temperatures much lower than the first ionization potentials, we derive an explicit expression for the bulk viscosity. We obtain that bulk viscosity can be many order of magnitude bigger than the shear viscosity. Our result for the relaxation time reveals that the Mandelstam-Leontovich approximation for the frequency dependence of the bulk viscosity is in practice an exact result for the cold plasmas. The illustrative numerical examples correspond to the plasma cocktail of the solar chromosphere at the height of the minimal polytropic index. We systemize also explicit formulae for the thermodynamics of the binary alkali-noble cocktails.The possible application for the acoustic heating of the inner solar atmosphere up to the transition region is shortly discussed together with the evaluation to confirm the theory by laboratory plasmas.