Scaling of Ignition and Burn in Inhomogeneous Inertial Confinement Fusion Hotspots

The performance of inertial confinement fusion (ICF) capsules is heavily dependent on the formation and shape of the hotspot, and the way these are influenced by the presence of different perturbations. Conversely, the evolution of the perturbations themselves changes due to the hotspot heat flow via electron thermal conduction, radiation transport and alpha transport. Understanding this interaction between perturbations and the hotspot is crucial to understanding the evolution of ignition and burn.

We examine the scaling in performance with increased capsule size and laser energy, presenting simulations using the in-house 3D radiation hydrodynamics code Chimera, upgraded with a Monte-Carlo Particle-in-Cell (PIC) alpha transport. We consider the impact of various perturbations such as radiation asymmetries and multi-mode Rayleigh-Taylor spikes on the energy scaling of both High-Foot and High-Density-Carbon (HDC)-style capsules, based on current National Ignition Facility (NIF) capsule experiments. Larger scales produce enhanced burn and therefore increased heat flow, and we explore how the effect of the resultant feedback loop between this heat flow and the perturbations varies with scale. We also study the scale requirements for 1MJ yields under these perturbation scenarios.