X-Ray Spectroscopy of Rapidly Heated Buried-Aluminum Layers

The thermal x-ray emission spectrum from rapidly heated solid targets containing a buried-aluminum layer was measured. The targets were driven by high-contrast 1$\omega $ or 2$\omega $ laser pulses at focused intensities up to $1 \times 10^{19}$ W/cm$^2$. Aluminum thermal lines in the 1.5- to 2-keV spectral range were measured with time-integrated and time-resolved spectrometers. The average plasma conditions in the buried layer were inferred by fitting x-ray spectra from a collisional-radiative atomic physics model to the measured data. The achievement of dense, high-temperature plasma conditions with an intense 2$\omega $ drive will be discussed. This material is based upon work supported by the Department of Energy National Nuclear Security Administration under Award Number DE-NA0001944 and the Stewardship Science Graduate Fellowship Grant Number DE-NA0002135.