Accuracy ofK-shell spectra modeling in high-density plasmas

We present spectroscopic measurements of the helium-like and lithium-like argon emission supported by Thomson scattering diagnostics on gas bag targets. These data provide critical tests of plasma spectroscopic K-shell models. In particular, we have measured the line radiation in the wavelength region of the He-like Ar1s²--1s3l transition (He-β) that is of interest for density and temperature measurements of plasmas from gas-filled targets (nₑ<~10²¹ cm^-3), laser ablation targets (nₑ<~10²² cm^-3), and inertial confinement fusion capsule implosions (nₑ>~10²⁴ cm^-3). The spectra show lithium-like dielectronic satellites on the red wing of the He-β line that are temperature sensitive and are known to influence the shape of the Stark-broadened line profiles observed from implosions. To examine the kinetics modeling of this complex, i.e., the He-β and its associated satellites, we have performed experiments in gas bag plasmas at densities of (0.6--1.1)×10²¹ cm^-3 where we independently determine the electron temperature with ultraviolet Thomson scattering. The comparison of the satellite intensities with kinetics modeling shows good agreement for satellites whose upper states are populated by dielectronic capture, but shows discrepancies for inner-shell collisional excited transitions.