Synthesis and characterization of diamond capsules for direct-drive inertial confinement fusion

Abstract

Aiming at improving performance of inertial confinement fusion (ICF) targets, we developed synthesis technology of diamond capsules. In direct-drive ICF for which a spherical target capsule is irradiated directly with intense laser light, laser imprinting due to irradiation non-uniformity on the capsule surface degrades symmetry of the target implosion and performance as a result. We demonstrated that material stiffness is the effective parameter for mitigation of laser imprinting [Kato, et al., Phys. Plasmas, 25, 032706 (2018)]. In this study, we fabricated polycrystalline diamond capsules as the ablator material of direct-drive ICF targets by using the hot filament chemical vapor deposition method. The capsule (diameter ~500 μm) with sphericity 99.7%, film thickness < 10 μm, and the surface smoothness <0.1 μm was obtained without mechanical polishing.