X-ray spectroscopy of hot dense plasmas using LLNL's upgraded Titan 2ω short-pulse laser.

We are developing an experimental platform at Lawrence Livermore National Laboratory's Jupiter Laser Facility to characterize x-ray emission from highly charged ions in the high-density (ne > 1023 cm-3), high-temperature (Te ∼ 1 keV) regime, leveraging the recently upgraded frequency-doubled short-pulse Titan laser. These measurements will provide experimental benchmarks for high electron density effects on atomic structure, including Stark broadening, ionization potential depression, density-dependent line shifts, and suppression of dielectronic recombination, effects that are relevant to spectral modeling packages used by both the high-energy-density and astrophysics communities. Here, we describe the current status of the platform and present results from first experiments using the upgraded frequency-doubling capability, including calibrated K-shell spectra acquired from five time-integrated x-ray channels. Comparisons with multi-electron radiator line shape calculations and with spectra recorded at the atomic weapons establishment's Orion Laser Facility indicate that the upgraded Titan laser reliably produces the necessary plasma conditions, establishing a foundation for systematic benchmarking of high-density atomic physics in future campaigns.