SPACE AND TIME-RESOLVED ABSORPTION-SPECTROSCOPY OF DIRECTLY AND INDIRECTLY DRIVEN EXPANDING PLASMAS

We have extended the technique of absorption spectroscopy to study the ion charge distribution and the areal mass density variations of expanding laser-produced and radiation-driven plasmas. Specifically, we will present space and time-resolved absorption spectroscopy measurements for K and L-shell ions (Mg and Ge) in the 8-11 Angstrom spectral range. The nanosecond plasmas were created either by direct laser irradiance in the case of Mg (up to 10(13) W/cm(2)) or by indirect x-ray heating (at a few 10(12) W/cm(2) x-ray irradiance). The ion population and areal mass of the expanding plasmas were deduced from the agreement between the experimental optical depths and the theoretical modelling of absorption derived from atomic data calculated either in a detailed configuration MCDF (Mg and Ge) or in a statistical UTA approach (Ge), both analysis being in good agreement. We will also present comparisons of the Mg and Ge data to space and time predictions of the hydrodynamical code CHIVAS.