High resolution simulations of ignition capsule designs for the National Ignition Facility

Ignition capsule designs for the National Ignition Facility (NIF) continue to evolve in light of improved physical data inputs, improving simulation techniques, and--most recently--experimental data from recent NIF sub-ignition experiments. This talk summarizes a number of recent changes to the cryogenic capsule design and some of our latest techniques in simulating its performance. Foremost, experiments have indicated harder x-ray drive spectra in NIF hohlraums than were predicted and used for previous capsule optimization studies. To accommodate this harder spectrum, the germanium ablator dopant concentration has been re-optimized based on a series of high resolution 2-D simulations resolving Legendre mode numbers as high as two thousand. Second, concern over the possibility of cooperative or nonlinear interaction of isolated defects on the ablator surface has motivated a series of fully 3-D capsule simulations. These simulations can use actual measured shell surfaces as initial conditions and include resolution to mode two hundred or higher.