Thin solid tamped foils were heated by the x-rays generated in spherical gold hohlraums which were irradiated by the high power laser ASTERIX IV with an energy of up to 500 J and a pulse duration of 0.4 ns. The sample foils were probed by the radiation of a back-lighter with a variable delay to the main beam. Previous opacity studies in the extreme uv range (G. Winhart et al., PRE, 53, R1332, 1996) have now been completed by measurements in the keV range by using a crystal spectrometer. We present K-shell absorption spectra of aluminium at temperatures between 20 and 30 eV. For the analysis we used local thermodynamic equilibrium opacity codes. The resulting mean ionization of the sample is compared with hydro-code simulations which were post-processed by solving the rate equations using a collisional radiative model.
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