Experimental basis for laser-plasma interactions in ignition hohlraums at the National Ignition Facility

A series of laser-plasma interaction experiments is presented using gas-filled hohlraums that shed light on the behavior of stimulated Raman scattering and stimulated Brillouin scattering at various plasma conditions encountered in indirect drive ignition designs. Detailed experimental results are presented that quantify the density, temperature, and intensity thresholds for both of these instabilities. In addition to controlling plasma parameters, the National Ignition Campaign relies on optical beam smoothing techniques to mitigate backscatter and the results presented show that polarization smoothing is effective at controlling backscatter. These results provide an experimental basis for the forthcoming experiments on National Ignition Facility.