Average-Atom Model for X-ray Scattering from Warm Dense Matter

TL;DR

This paper presents an average-atom model-based scheme for analyzing X-ray Thomson scattering in warm dense matter, focusing on bound electron contributions and providing a practical diagnostic tool for various plasma materials.

Contribution

It introduces a simplified, model-based method to interpret X-ray scattering spectra in warm dense matter, emphasizing bound electron effects.

Findings

Inelastic scattering by bound electrons dominates at high momentum transfer for certain metals.

The scheme effectively distinguishes contributions from free and bound electrons in the scattering spectrum.

Applications demonstrate the model's utility for different dense plasma materials.

Abstract

A scheme for analyzing Thomson scattering of x-rays by warm dense matter, based on the average-atom model, is developed. Emphasis is given to x-ray scattering by bound electrons. Contributions to the scattered x-ray spectrum from elastic scattering by electrons moving with the ions and from inelastic scattering by free and bound electrons are evaluated using parameters (chemical potential, average ionic charge, free electron density, bound and continuum wave functions, and occupation numbers) taken from the average-atom model. The resulting scheme provides a relatively simple diagnostic for use in connection with x-ray scattering measurements. Applications are given to dense hydrogen, beryllium, aluminum, titanium, and tin plasmas. At high momentum transfer, contributions from inelastic scattering by bound electrons are dominant features of the scattered x-ray spectrum for aluminum, titanium, and tin.