High-order satellites and plasma gradients effects on the Ar He β line opacity and intensity distribution

Abstract

We study the effects of high-order n=4 Li-like satellites and plasma density and temperature gradients on the Ar He β line opacity and intensity distribution, using a spectroscopic-quality atomic kinetics and radiation transport model. The model self-consistently accounts for NLTE level population kinetics, Stark broadened line shapes, and radiation transport effects. High-order satellites with a spectator electron in n=4 make a significant contribution to both opacity and line intensity distribution of the Ar He β composite line for plasma conditions typical of ICF imploded cores. We also discuss the impact of plasma density and temperature gradients on the formation of this spectral feature and show that the combined effect of gradients and opacity can lead to a characteristic round shape in the center of the He β line.