A Detailed Configuration Accounting for the Hot Plasma Bound-Free Opacity Calculation

TL;DR

This paper presents a probabilistic reformulation of the Fourier transform method to improve the calculation of bound-free opacity in hot plasmas, accounting for configuration effects and threshold spreads.

Contribution

It introduces a novel probabilistic approach for detailed configuration accounting in bound-free opacity calculations, enhancing accuracy over previous methods.

Findings

The method accounts for fluctuations in shell occupation numbers.

It improves the modeling of ionization threshold spreads.

The approach offers a more accurate bound-free opacity estimation.

Abstract

The calculation of the hot plasma bound-free opacity according to the average atom models often leads to a noticeable effect of initial configuration on the shell ionization threshold. For the related problem of taking into account the impact of configurations while calculating bound-bound opacity, G. Hazak and Y. Kurzweil developed a method within the Super Transition Arrays approach. Fourier transform method is the adaptation of their method for a Detailed Configurations Accounting. The bound--free opacity coefficient qualitative behavior makes it somewhat difficult to construct a direct analogue of Fourier transform method of Detailed Configurations Accounting for its calculation. We use the probabilistic reformulation of the method to obtain the expressions for the bound--free opacity coefficient that take into account the spread of ionization thresholds due to the shell occupation numbers fluctuations.