Hollow foam microshells for liquid-layered cryogenic inertial confinement fusion targets

Abstract

Future U.S. inertial confinement fusion (ICF) targets will use capsules, 1–2 mm in diameter, with uniform 100 μm thick, cryogenic fuel layers. Research is currently underway to identify optimal methods for producing these thick, uniform layers. One method is to use a spherical polymer foam layer within a full density polymer overcoat to support the fuel. Targets of this type, 0.4–0.8 mm in diameter, with 10–30 μm walls, have been developed by the Institute of Laser Engineering at Osaka University, Japan. Reported here are the results obtained from work to extend the method to the future ICF target design. Overcoated foam shells of the proper dimensions were produced, but their optical properties precluded the use of current diagnostics to determine the amount and uniformity of the fuel fill. Briefly outlined are options for improving the optical properties.