Opacity measurements in a hot dense medium

Measurements of the opacity of aluminum in a well characterized, hot, dense , laser produced plasma are reported. Measurements of the absorption of X-r ays by 1 to 2 transitions in Al XII through Al VIII have been made in a las er-heated slab plasma at the measured temperature and density of 58 +/- 4 e V and 0.020 +/- 0.007 g cm(-3). Separate measurements of the temperature an d density were made. The conditions in the plasma were determined to be rep roducible, spatially uniform, and in nearly complete local thermodynamic eq uilibrium. The absorption spectra and the temperature-density data obtained provide an improved means for comparison with detailed atomic physics and opacity calculations.