Post-Shot Modeling of Double Shell Implosions Using Integrated Hohlraum Simulations

The Double Shell Campaign is an inertial confinement fusion concept with the goal of achieving volumetric burn. Controlling the shape of the implosion to maintain spherical symmetry is imperative for robust performance. To understand target asymmetries originating from the laser-driven hohlraum, we model indirectly-driven double shell experiments at the National Ignition Facility using LANL’s Eulerian radiation hydrodynamic code. We consider calculations that use either local thermodynamic equilibrium (LTE) or non-local thermodynamic equilibrium (nLTE) for the hohlraum, a window on the laser entrance hole (LEH), and a variable multiplier on the total laser power. We find that including both the LEH window and using nLTE are necessary to mitigate unphysical low mode inner shell growth. Run in this way, the simulations are able to more accurately match key metrics from double shell experimental data in terms of both the shape and shell trajectories as extracted from synthetic radiographs. We also present simulations that include small scale non-uniformities on the layers of the capsule, and we contrast using the measured values directly to using a phase-randomized reconstruction from a power spectrum.