High resolution, sub-picosecond x-ray spectroscopy of K-shell emitters to characterize plasma emissivity measurement.

Short pulse laser (SPL) heated matter has opened an avenue to studying matter at conditions previously unattainable. While SPLs can generate matter at extreme densities and temperatures, characterization of the heated matter can be extremely challenging. The conditions are dynamic and require careful monitoring of the plasma evolution. Atomic processes under these conditions can provide a powerful tool to study fundamental plasma properties as they evolve. When utilizing the x-ray emission from these plasmas, it is often useful to resolve spectral details with high resolution. Sub-picosecond, time-resolved, high-resolution spectroscopy has previously been reported. We present a similar diagnostic (STreaked Orion High-Resolution X-ray spectrometer, or STOHREX) to measure the temporal evolution of spectral features with high spectral resolution. The diagnostic is the result of combining a high-resolution x-ray spectrometer with the LLNL sub-picosecond x-ray streak camera. The diagnostic was demonstrated in two campaigns: (1) To study spectral lineshapes using the 40 fs, 400 nm, Colorado State University ALEPH laser, and (2) to study buried layers using the 500 fs, 532 nm Atomic Weapons Establishment's Orion laser.