Picosecond Time-Resolved Temperature and Density Measurements with K-Shell Spectroscopy

The thermal x-ray emission from rapidly heated solid targets containing a buried-aluminum layer was measured to track the evolution of the bulk plasma conditions. The targets were driven by high-contrast 1$\omega $~laser pulses at focused intensities up to~1~$\times $~10$^{\mathrm{19}}$~W/cm$^{\mathrm{2}}$. A streaked x-ray spectrometer recorded the $\mbox{Al\thinspace He}_{\alpha } $ and lithium-like satellite lines with 2-ps temporal resolution and moderate resolving power ($E \mathord{\left/ {\vphantom {E {\Delta E\approx 1000}}} \right. \kern-\nulldelimiterspace} {\Delta E\approx 1000})$. Time-integrated measurements over the same spectral range were used to correct the streaked data for variations in photocathode sensitivity. Linewidths and intensity ratios from the streaked data were interpreted using a collisional radiative atomic kinetics model to provide the average plasma conditions in the buried layer as a function of time. Experimental uncertainties in the measured plasma conditions are quantified within a consistent model-dependent framework. The data demonstrate the production of a 330$\pm $56 eV, 0.9$\pm $0.3 g/cm$^{\mathrm{3}}$ plasma that evolves slowly during peak $\mbox{He}_{\alpha }_{\mathrm{\thinspace }}$emission. This material is based upon work supported by the Department of Energy National Nuclear Security Administration under Award Number DE-NA0001944.