Charge State Distributions in Dense Plasmas

TL;DR

This paper introduces a new variational model for calculating charge state distributions in hot, dense plasmas, addressing limitations of traditional methods like Saha-Boltzmann, and providing a computationally efficient approach with good accuracy.

Contribution

The paper presents a novel variational model that incorporates orbital relaxation effects for more accurate charge state distributions in dense plasmas.

Findings

Good agreement with average atom calculations

Breakdown of Saha-Boltzmann in dense regimes

Mixed results with chemical models

Abstract

Charge state distributions in hot, dense plasmas are a key ingredient in the calculation of spectral quantities like the opacity. However, they are challenging to calculate, as models like Saha-Boltzmann become unreliable for dense, quantum plasmas. Here we present a new variational model for the charge state distribution, along with a simple model for the energy of the configurations that includes the orbital relaxation effect. Comparison with other methods reveals generally good agreement with average atom based calculations, the breakdown of the Saha-Boltzmann method, and mixed agreement with a chemical model. We conclude that the new model gives a relatively inexpensive, but reasonably high fidelity method of calculating the charge state distribution in hot dense plasmas, in local thermodynamic equilibrium.