ADAPTING THE DECOMPOSABLE MANDREL TECHNIQUE TO BUILD SPECIALTY ICF TARGETS

In this paper we describe our efforts to produce ICF target capsules w ith either controlled inner surface roughness of thin metallic diagnos tic layers by adapting the decomposable mandrel technique previously d eveloped at LLNL. To modify the capsule's inner surface we laser ablat ed a pattern on a poly(alpha-methylstyrene) (PAMS) shell, overcoated i t with plasma polymer and then thermally decomposed the inner mandrel to leave the plasma polymer shell with the imprint of the laser ablate d mandrel pattern. In this fashion we have been able to produce shells with controlled inner surface bumps. However, these bumps are correla ted with outer surface pits. To place a thin metallic diagnostic layer on the inner capsule surface we applied a 50 Angstrom titanium sputte r coating to a smooth PAMS shell, overcoated with plasma polymer, and then thermally decomposed the mandrel to leave a plasma polymer shell with the titanium layer on the inner surface, Surface analysis showed that this process resulted in shells with a relatively long wavelength roughness, possibly due to the action of the metallic layer as a perm eation barrier.