Implosion performance of subscale beryllium capsules on the NIF.

Many inertial fusion designs use capsules made of beryllium, as its high mass ablation rate is advantageous. We present the first systematic experimental study of indirectly driven beryllium capsules with a cryogenic deuterium-tritium fuel layer. "Subscale" capsules, 80% of the nominal National Ignition Facility point design radius, show optimal performance with the remaining mass of ∼6–7%. A buoyancy-drag mix model explains the implosion performance, suggesting that fuel-ablator mix is the dominant degradation mechanism. Increasing the capsule scale is predicted to reduce the impact of fuel-ablator mix and achieve high performance. [ABSTRACT FROM AUTHOR]