COMPETING EFFECTS OF COLLISIONAL IONIZATION AND RADIATIVE COOLING IN INERTIALLY CONFINED PLASMAS

We describe an experimental investigation, a detailed analysis of the Ar XVII 1s(2 1)S-1s3p P-1 (He beta) line shape formed in a high-energy -density implosion, and report on one-dimensional radiation-hydrodynam ics simulation of the implosion. In this experiment trace quantities o f argon are doped into a lower-Z gas-filled core of a plastic microsph ere. The dopant level is controlled to ensure that the He beta transit ion is optically thin and easily observable. Then the observed line sh ape is used to derive electron temperatures (T-e) and electron densiti es (n(e)). The high-energy density plasma, with T-e approaching 1 keV and n(e) = 10(24) cm(-3), is created by placing the microsphere in a g old cylindrical enclosure, the interior of which is directly irradiate d by a high-energy laser; the x rays produced by this laser-gold inter action indirectly implode the microsphere. Central to the interpretati on of the hydrodynamics of the implosions is the characterization and understanding of the formation of these plasmas. To develop an underst anding of the plasma and its temporal evolution, time-resolved T-e and n(e) measurements are extracted using techniques that are independent of the plasma hydrodynamics. Comparing spectroscopic diagnostics with measurements derived from other diagnostic methods, we find the spect roscopic measurements to be reliable and further we find that the expe riment-to-experiment comparison shows that these implosions are reprod ucible.