Theory of warm ionized gases: equation of state and kinetic Schottky anomaly

TL;DR

This paper develops a theoretical framework for warm ionized gases using Lennard-Jones potentials, predicting specific heat peaks due to ionization and analyzing implications for sonoluminescence.

Contribution

It introduces a new set of state equations for warm atomic gases with ionization, linking kinetic Schottky anomalies to atomic density and ionization processes.

Findings

Predicted specific heat peaks at ionization points.

Good agreement of plasma electron density with experiments.

Enhanced Schottky anomaly at low densities.

Abstract

Based on accurate Lennard-Jones type interaction potentials, we derive a closed set of state equations for the description of warm atomic gases in the presence of ionization processes. The specific heat is predicted to exhibit peaks in correspondence to single and multiple ionizations. Such kinetic analogue in atomic gases of the Schottky anomaly in solids is enhanced at intermediate and low atomic densities. The case of adiabatic compression of noble gases is analyzed in detail and the implications on sonoluminescence are discussed. In particular, the predicted plasma electron density in a sonoluminescent bubble turns out to be in good agreement with the value measured in recent experiments.