Time-resolved temperature measurements of radiatively heated tamped MgO foils by Kα absorption spectroscopy

Abstract In this paper we present time-resolved temperature measurements of a radiatively heated, thin tamped foil via Kα absorption spectroscopy. The sample foil was 1500 A MgO, tamped on both sides with 1000 A paralyene, and was heated by soft x-rays transmitted through the back side of a separate laser-irradiated 1500 A Au foil. The resulting plasma was then backlit by a separate laser-irradiated front-surface U foil, providing a time-resolved K -shell absorption spectrum over the duration of the heating phase. We compare the resulting data to synthetic spectra obtained from detailed simulations of the heating and expansion of the tamped foils, and find poor agreement. Much better agreement is obtained when we determine the temperatures through best-fit absorption spectra which assume temperatures ∗> 35% higher than predicted; the reason for this discrepancy is not yet understood.