Increasing the Neutron Yield of Direct-Drive Inertial Confinement Fusion Implosions Using a 3-D Contoured Shell

Non-uniformities in the illumination of a direct drive inertial confinement fusion (DD-ICF) target cause a significant decrease in fusion yield. These non-uniformities induce perturbations in the shape of the inflight shell front. The energy required to create these perturbations detracts from the energy available for the fusion reaction. Additionally, the decrease in sphericity of the inflight shell front results in a larger surface area and thus promotes the conduction of heat away from the final hot-spot at stagnation. To mitigate these adverse effects, we investigate the impact of introducing a 3-D contour to the target surface using the 3D code ASTER1. We observe that the perturbations in shell front position caused by the contour destructively interfere with those induced by the non-uniform laser illumination. We calculate the shell front position, areal density, and electron temperature throughout the implosion to determine the optimal contour shape. This study has resulted in the identification of several contour shapes that have a significant effect on the fusion yield.

1 I. V. Igumenschvev et al, Physics of Plasmas 23, 052702 (2016)