Beryllium capsule implosions at a case-to-capsule ratio of 3.7 on the National Ignition Facility

Beryllium is a candidate ablator material for indirect-drive inertial confinement fusion experiments, motivated by its high mass ablation rate, which is advantageous for implosion coupling efficiency and stabilization of the ablation-front instability growth. We present new data on the shock propagation, in-flight shape, and hot spot self-emission shape from gas-filled capsules that demonstrate the feasibility of predictable, symmetric, controllable beryllium implosions at a case-to-capsule ratio of 3.7. The implosions are round (Legendre mode 2 amplitude ≲5%) at an inner beam power and the energy fraction of 26%–28% of the total, indicating that larger beryllium capsules could be driven symmetrically using the National Ignition Facility.