Experimental characterization of a strongly coupled solid density plasma generated in a short-pulse laser target interaction

We have measured high resolution copper K alpha spectra from a picosecond high intensity laser produced plasma. By fitting the shape of the experimental spectra with a self-consistent-field model which includes all the relevant line shifts from multiply ionized atoms, we are able to infer time and spatially averaged electron temperatures (T-e) and ionization state (Z) in the foil. Our results show increasing values for T-e and Z when the overall mass of the target is reduced. In particular, we measure temperatures in excess of 200 eV with Z similar to 13-14. For these conditions the ion-ion coupling constant is Gamma(ii) similar to 8-9, thus suggesting the achievement of a strongly coupled plasma regime. (c) 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim