TIME-RESOLVED TEMPERATURE-MEASUREMENTS OF RADIATIVELY HEATED TAMPED MGO FOILS BY K-ALPHA ABSORPTION-SPECTROSCOPY

In this paper we present time-resolved temperature measurements of a r adiatively heated, thin tamped foil via K alpha absorption spectroscop y. The sample foil was 1500 Angstrom MgO, tamped on both sides with 10 00 Angstrom paralyene, and was heated by soft x-rays transmitted throu gh the back side of a separate laser-irradiated 1500 Angstrom Au foil. The resulting plasma was then backlit by a separate laser-irradiated front-surface U foil, providing a time-resolved K-shell absorption spe ctrum over the duration of the heating phase. We compare the resulting data to synthetic spectra obtained from detailed simulations of the h eating and expansion of the tamped foils, and find poor agreement. Muc h better agreement is obtained when we determine the temperatures thro ugh best-fit absorption spectra which assume temperatures >35% higher than predicted; the reason for this discrepancy is not yet understood.