On the Influence of the Ionization-Recombination Processes on Hydrogen Plasma Polytropic Index

TL;DR

This paper analytically investigates how ionization-recombination processes affect the polytropic index of hydrogen plasma, revealing measurable deviations from ideal values and demonstrating a method extendable to other gases.

Contribution

It provides an analytical calculation of the hydrogen plasma polytropic index considering ionization effects, illustrating deviations from ideal behavior and offering a framework for other gases.

Findings

Partially ionized hydrogen plasma is not exactly polytropic.

Deviations from the mono-atomic value 5/3 are measurable.

The approach can be extended to arbitrary gas mixtures.

Abstract

The polytropic (adiabatic) index for pure hydrogen plasma is analytically calculated as function of reciprocal temperature and degree of ionization. Additionally, the polytropic index is graphically represented as a function of temperature and density. It is concluded that the partially ionized hydrogen plasma cannot be exactly polytropic. The calculated deviations from the mono-atomic value 5/3 are measurable. The analytical result for pure hydrogen plasma is a test example how this approach can be extended for arbitrary gas cocktail.