Generating uniform high-Z plasmas on the OMEGA and NIF laser facilities for radiative properties studies*

Previous efforts to obtain benchmarking data for atomic-kinetics modeling of non-local thermodynamic equilibrium (non-LTE) plasmas by direct laser heating of tamped high-Z foils have successfully demonstrated uniform, sub-critical density, multi-keV electron temperature Au plasmas. Such conditions are relevant for understanding the influences of coronal plasmas in inertial confinement fusion hohlraums – i.e., the “Au bubble” which influences hohlraum drive symmetry and generates undesirable capsule preheat via M-band line-radiation – but reaching higher densities of relevance to the LTE wall conditions (where most of the heated hohlraum mass is located) is nontrivial as the high-Z sample does not heat uniformly until it becomes sub-critical throughout. We discuss the potential risks and benefits of using x-rays as an alternative heating source to isochorically heat tamped Au foils to hohlraum-wall-relevant plasma conditions using multi-keV line-radiation from laser driven, sub-critical density, Ag nanowire foam x-ray sources. We present radiation-hydrodynamic simulations studying the high-Z plasma evolution and sensitivity to target/x-ray drive design, along with preliminary designs for experiments on both the OMEGA and NIF laser facilities.