Absorption spectroscopy of a radiatively heated samarium plasma

Abstract

We present measurements of the samarium $\mathrm{}(Z=62\mathrm{})\mathrm{}$ $M$-shell absorption band around 11 Å (1.1 keV) at electron temperatures between 5 and 20 eV. Using point projection absorption spectroscopy, we measured the absolute transmission of an x-ray probe beam through a radiatively heated samarium plasma at different drive temperatures. The measurements show two principal absorption features corresponding to the spin-orbit-split $3d-4f$ transitions of Sm IV–Sm X ions. The influence of the heating on the spectral opacity shape was characterized by a shift of the absorption features to higher energy for a hotter plasma. The data are compared with calculations done with the superconfiguration code SCO for different plasma temperatures. The temperature and average ionization inferred from the analysis of the experiment are compared to radiative hydrodynamic simulations.