3D HYDRA Capsule Studies on the Effect of Hohlraum Windows

We present low-resolution three-dimensional radiation hydrodynamic simulation studies of capsule-only implosions using the code HYDRA [1]. These simulations are capable of resolving radiation drive asymmetries with spherical harmonic degrees of at least five and utilize Particle Monte Carlo neutronics. The simulations are heavily diagnosed with synthetic neutron and x-ray diagnostics, similar to the actual diagnostics used on the National Ignition Facility. These simulations are executed on the TRINITY supercomputer at Los Alamos under the Advanced Technology Computing Campaign.

This work focuses on sensitivity studies affecting capsule implosion stability due to diagnostic windows in the hohlraum, in support of the Windowless Hohlraum experimental campaign. The three-dimensional drive asymmetries are derived from VISRAD [2] view factor simulations, accounting for time-dependent laser beam power imbalance, capsule ablation, and hohlraum wall expansion. We will present the results of the sensitivity studies with various hohlraum-window models and compare them to experimental observations.

[1] M. M. Marinak, et al., Phys. Plasmas 8, 2275 (2001)

[2] J. J. MacFarlane, J. Quant. Spectr. Rad. Transfer, 81, 287 (2003)