Opacity measurements: Extending the range and filling in the gaps

A series of experiments to explore Ge opacity at temperatures where the M-shell is almost filled will be discussed. Data are obtained at lower temperatures than previously explored and allow us to investigate the role of atomic structure calculations and their impact on opacity scalings. The experiment uses the Nova. laser to irradiate a gold hohlraum within which a CH-tamped Ge sample is radiatively heated. A Nd backlight probes the sample 2 nsec later to produce Ge spectral absorption features in the 1.2-1.5 keV energy range. Temperature is monitored by the use of an Al dopant and density is monitored by measuring the edge-on expansion of the sample. Temporal resolution of similar to 200 psec is obtained by using a short pulse backlight. Calculations in this photon energy region show significant changes in the spectral features. (C) 1997 Elsevier Science Ltd. All rights reserved.