K-SHELL SPECTROSCOPY OF RADIATIVELY HEATED ALUMINUM

Thin solid tamped foils were heated by the x-rays generated in spheric al gold hohlraums which were irradiated by the high power laser ASTERI X 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 va riable delay to the main beam. Previous opacity studies in the extreme uv range (G. Winhart er al., PRE, 53, R1332, 1996) have now been comp leted by measurements in the keV range by using a crystal spectrometer . We present K-shell absorption spectra of aluminium at temperatures b etween 20 and 30 eV. For the analysis we used local thermodynamic equi librium opacity codes. The resulting mean ionization of the sample is compared with hydro-code simulations which were post-processed by solv ing the rate equations using a collisional radiative model. (C) 1997 P ublished by Elsevier Science Ltd. All rights reserved.