Work

A comparison of time-dependent Cloudy astrophysical code simulations with experimental X-ray spectra from keV laser-generated argon plasmas

Year: 2025

Type: article

Abstract: • Photoionized Ar plasma is generated in experiments using X-ray line emission from laser irradiated Ag foils. • This use of line emission source allows keV radiation to dominate over softer X-rays and thus mimics the effect of a blackbody with a higher spectral temperature. • A comparison of experimental K-β X-ray Ar spectra with photoionized plasma modelling using time resolved capabilities of the Cloudy astrophysical code is presented. • The good agreement between experimental and modelled K-β spectra indicates that photoionized laboratory plasmas can be successfully modelled using codes specifically made for astrophysical modelling. We have generated strongly photoionized Ar plasmas in experiments designed to use primarily X-ray L-shell line emission generated from Ag foils irradiated by the VULCAN high-power laser at the UK Central Laser Facility. The principle of the experiment is that use of line emission rather than the usual sub-keV quasi-blackbody source allows keV radiation to play a more dominant role compared to softer X-rays and thus mimic the effect of a blackbody with a higher effective spectral temperature. Our aim is to reproduce in the laboratory the extreme photoionization conditions found in accretion-powered astrophysical sources. In this paper, we compare the experimental results on K-β X-ray Ar spectra with modelling using the time-dependent version of the Cloudy astrophysical code. The results indicate that photoionized laboratory plasmas can be successfully modelled with codes such as Cloudy that have been developed for application to astrophysical sources. Our comparison of simulation and experiment shows that the flux of sub-keV photons that photoionize the outer-shell electrons can have a significant effect, and that detailed measurements of the X-ray drive spectrum across all photon energy ranges are crucial for accurate modelling of experiments.

Source: Journal of Quantitative Spectroscopy and Radiative Transfer

DOI: 10.1016/j.jqsrt.2025.109720