Thermodynamics of Equilibrium Alkali Plasma. Simple and Accurate Analytical Model for Non-Trivial Case

TL;DR

This paper introduces a simple, universal analytical equation of state for alkali metals in equilibrium gas phase, accurately matching experimental data across wide pressure and temperature ranges, and supporting the principle of corresponding states.

Contribution

A novel, simple analytical model for the equation of state of alkali metals in equilibrium gas phase, applicable to all alkali elements and validated against experimental data.

Findings

Accurately reproduces experimental data for alkali gases up to 10^5 Pa and 3000 K.

Provides expressions for thermal and caloric coefficients.

Confirms the principle of corresponding states for alkali elements.

Abstract

Analytical equation of state for pure alkali metals (lithium, sodium, potassium, rubidium and cesium) in equilibrium gas phase is proposed. This equation has a simple form, generalizes the equation of state for a perfect gas and is universal for all alkali elements. It correctly reproduces the experimental data for the equilibrium gas phase over a wide range of pressures (up to $\sim 10^5$~Pa) and temperatures (up to $\sim 3 \cdot 10^3$~K). On the basis of this equation of state, expressions for thermal and caloric coefficients as well as for \textit{other physical characteristics} are obtained. The results of this study confirm feasibility of the principle of corresponding states in relation to the group of alkali elements.