Spectroscopic line shape measurements at high densities

Meeting on Radiative Properties of Hot Dense Matter III, LAWRENCE LIVERMORE NATL LAB, LIVERMORE, CALIFORNIA, 1996International audienceA comprehensive spectroscopic investigation of plasmas at extreme conditions produced by indirectly driven inertially confined implosions is described. In these experiments argon is doped into the gas filled core of implosion targets and the Ar K-shell emission is used to make time resolved measurements of electron density and electron temperature. The electron density is derived from the Stark broadened Ar XVII 1s(2)-1s3p line shape, the electron temperature is derived from the line intensity ratio of the Ar XVII ls(2)-ls(3)p transition and the lithium-like dielectronic satellites 2l2l', 2l3l' lying on the low energy side of the resonance line. We give examples of the experimental data and compare the extracted time histories of electron density and electron temperature with simple radiation hydrodynamic simulations, where broad agreement is found. Detailed line shape measurements of the Ar XVII ls(2)-ls3p transition are presented and the absence of an intensity dip at line center in the experiment results is discussed. The validity of the quasi-static non approximation for these plasma conditions is tested by varying the mass of the fill gas in the core. Results from deuterium, deuterated methane, and nitrogen filled implosions are presented and indicate ion dynamic effects are not responsible for the line center discrepancy. We discuss other possibilities including spatial gradients in the core affecting measurements of the intrinsic lineshape. (C) 1997 Published by Elsevier Science Ltd. All nights reserved