Properties and fabrication status of capsules for ignition targets in inertial confinement fusion experiments

The inertial confinement fusion program has proposed a laser capable of producing ignition and gain as the next step. Several choices exist in the design and production of capsules. In this paper the important features of each ablator material and the status of production are summarized. The design consists of ablators made of germanium-doped carbon hydrogen (CH), beryllium doped copper, polyimide, B4C and diamond. The CH and beryllium capsules are two of the most important choices. Compared with the beryllium shell, the CH shell has no microstructure and has a transparent wall that allows optical characterization of the fuel ice layer. The CH shell has the advantage that the specification can be easy to satisfy the ignition acquirements. The current ignition point has been designed in USA since 2010. The ignition target design has a series of demands for the capsule, such as capsule dimensions, coating density, void defects and volume, surface roughness, uniformity, doping and impurity levels. Now, the CH capsule can meet ignition requirements in USA, while the relevant work has just started in China.