Using Polar Direct Drive Experiments on the National Ignition Facility to Validate 2D Radiation-Hydrodynamic Energy Coupling Models

Polar-direct-drive (PDD) solid sphere experiments using 2.1-mm diameter CH targets were performed on the National Ignition Facility (NIF) to evaluate energy-coupling models in 2-D radiation-hydrodynamics codes. Data from the Scattered-Light Time-history Diagnostic (SLTD)[1] and the Full-Aperture Backscatter Stations (FABS) were used to measure time resolved scattered light at 350 to 351 nm (Stimulated Brillouin scattering). The trajectory of converging shocks and the resulting density profile was probed by a Cu backlighter and captured by gated x-ray detectors (GXD) to yield radiographs. A multiple-shock design was used to assess sensitivity to cross-beam energy transfer (CBET) during peak power. Comparison of the scattered light distribution and inferred density profiles to the radiation-hydrodynamics code DRACO, including cross beam energy transfer (CBET) and non-local heat transport models, will be discussed.

[1] M. J. Rosenberg et al., Rev. Sci. Instrum. 92, 033511 (2021).