The First NLTE Gold Buried Layer Experiment on the NIF

An experiment has been done at the NIF using a buried layer platform to study the radiative properties of non-local thermodynamic equilibrium (NLTE) gold plasma at an electron temperature of ∼3 keV and an electron density of ∼10²¹cm^-3. The targets used consisted of a 625 μm diameter, 1900 Å, thick dot with a 1:4.5 atomic mix of gold and zinc in the center of a 2500 μm diameter, 10 μm thick beryllium tamper. Lasers heat the target from both sides for 3.0 ns. The size of the microdot vs time was measured side-on with x-ray imaging. The radiant x-ray power was measured with a low-resolution, absolutely calibrated x-ray spectrometer (DANTE). The electron temperature was inferred from the measured zinc K-shell emission. The ionization balance of the gold is inferred from the measured L-shell emission of the gold. A comparison of the zinc K-shell spectrum and gold L-shell spectrum to the atomic kinetics code SCRAM is presented.