Current capsules used at the National Ignition Facility utilize a single-shell design comprised of a single ablator material. Although single-shell designs are currently the standard design, they suffer from several physics disadvantages, such as sensitivity to asymmetries and instabilities. The double shell is a proposed design utilizing a high-Z inner metal shell with a low-Z outer shell that is intended to mitigate the issues associated with typical single-shell designs.

Electroplating is one method that can be utilized to fabricate high-Z metal shells. Au is one particular material that can be electroplated with high density and uniformity. Capsule fill tube assemblies (CFTAs) built from these Au shells have passed all cryogenic leak tests. The shells have a low native surface roughness and are free of voids. Au shells have been successfully fabricated, characterized, and built into CFTAs.