Dependences of morphology and surface roughness on growth conditions of diamond capsules for the direct-drive inertial confinement fusion

In order to achieve the ignition by direct-drive inertial confinement fusion (ICF), smooth and symmetric fuel capsule is required. Our previous research found that stiffness of the capsule material contributes to reduce the laser imprinting. Therefore, diamond is considered to be the most promising candidate as the stiff ablator material for direct-drive ICF capsule. In this study, aiming at improving the surface roughness on the diamond capsule, we obtained dependence of methane concentration and gas pressure on surface roughness and morphology by hot filament chemical vapor deposition technique.