Progress in the Production of Materials and Fabrication of NIF Beryllium-Copper Ignition Capsules at Los Alamos National Laboratory

Work is underway at Los Alamos National Laboratory to fabricate machined-and-bonded target capsules of Be-6 wt% Cu for the National Ignition Facility. Significant progress has been made in producing material with the desired composition, purity, and homogeneity of composition, by arc melting. This material is thermomechanically processed by equal channel angular extrusion, to break down the coarse ascast structure and refine the grain size, to about 20 m. Machining with diamond tooling results in a significant improvement of the as-machined roughness, that also results in improved bond strengths. Bonding with a sputtered layer of Al can achieve high strengths with a bond 1.2 m thick, and thinner bonds are being investigated. Laser-drilled holes and fill-tube counterbores produced by electrodischarge machining appear to be feasible, but will require improvements in specimen positioning.