Polishing of Metal, Foam, and Si-Doped GDP Capsules for Use as ICF Targets

Abstract

Spherical targets with a smooth uniform surface are required for inertial confinement fusion experiments. This paper examines polishing as a method of decreasing the surface roughness of tungsten (W) capsules, chromium (Cr) capsules, SiCH [Si-doped glow discharge polymer (GDP)] capsules, and GDP-coated General Atomics–Carbon Hydrogen (GA-CH) foam beads. As expected, increasing the time spent polishing metal (W, Cr) capsules corresponded to decreasing roughness. Despite the decrease in overall surface roughness of Cr capsules, defects present in the batch initially were amplified through polishing. For SiCH capsules, increasing polishing time decreased the surface roughness, though the yield of usable capsules was affected by cracks induced through polishing. While polishing results for GDP-coated foam beads did not show consistent decrease in roughness, the polishing process did not result in the collapse of any of the foams, demonstrating the potential for polishing as a method of decreasing roughness.