Experimental examination of ablator mix, electron temperature and shell opacity variations during the burn phase of inertially confined capsule implosions on the National Ignition Facility*

Hydro-instabilities in ICF implosions can cause ablator mix into the plasma hot spot and shell rho-r variations which impact confinement, volume, temperature, density and pressure of the stagnated DT fuel assembly and subsequent nuclear yield performance. Therefore, it is crucial to experimentally diagnose mix, ablator opacity and hot spot Te in ICF implosions in order to better understand the capsule stagnation and burn process. In the past, different types of hydrodynamic instabilities, originating from the capsule surface roughness, support tent and fill-tube have been identified as possible fusion performance degrading mechanisms. Using x-ray penumbral imaging we obtain differentially filtered (6-30keV), high-resolution (4-5um), hot spot images. By combining images obtained above and below the ablator opacity threshold as well as images filtered for high-Z dopant emission we can spatially separate such hydrodynamic mix features and assess Te variations during the burn phase. We will present our progress by examining penumbral images of a series of recent high-density carbon, CH and Be ablator ICF implosions carried out on the NIF.