Simulation of Dopant Spectral Emission in Z-Pinch Dynamic Hohlraum Experiments

Summary form only given. We report on the analysis of X-ray spectra obtained from doped low-density foams in dynamic hohlraum Z-pinch experiments at Sandia National Laboratories. In these experiments, ~16-18 MA of current is delivered to a load comprised of a tungsten wire array which surrounds a low-density cylindrical CH foam. The foam is doped with ~1% SiO₂ to provide diagnostic information on the time-dependent evolution of the foam conditions. The Z-pinch magnetic field accelerates the W plasma radially inward, reaching velocities ~a fewtimes10⁷ cm/s. As the W plasma strikes the foam, a strong shock propagates through the foam, with temperatures behind the shock reaching ~a fewtimes10² eV. Time- and space-resolved X-ray spectra from Si K-shell lines are recorded, providing spectra from regions both within the shock and ahead of the shock. Using a multi-dimensional collisional-radiative spectral analysis code, we investigate the influence of photopumping of Si transitions in the unshocked foam due to radiation emitted by the shocked foam region. We will present results from recent simulations, and discuss the sensitivity of the spectra to the conditions in the shocked and unshocked foam regions