Dielectronic satellite emission from a solid-density Mg plasma: relationship to models of ionisation potential depression

TL;DR

This study investigates dielectronic satellite emission from solid-density magnesium plasmas created by x-ray laser heating, comparing experimental data with ionisation potential depression models and density functional theory predictions.

Contribution

It provides experimental validation that ionisation potential depression models should lie between Stewart-Pyatt and Ecker-Kroll predictions for high charge state ions.

Findings

Dielectronic satellites confirm M-shell electrons remain bound at high charge states.

Ionisation potential depression models need to be between Stewart-Pyatt and Ecker-Kroll.

Results align with recent Density Functional Theory calculations.

Abstract

We report on experiments where solid-density Mg plasmas are created by heating with the focused output of the Linac Coherent Light Source x-ray free-electron-laser. We study the K-shell emission from the Helium and Lithium-like ions using Bragg crystal spectroscopy. Observation of the dielectronic satellites in Lithium-like ions confirms that the M-shell electrons appear bound for these high charge states. An analysis of the intensity of these satellites indicates that when modelled with an atomic-kinetics code, the ionisation potential depression model employed needs to produce depressions for these ions which lie between those predicted by the well known Stewart-Pyatt and Ecker-Kroll models. These results are largely consistent with recent Density Functional Theory calculations.