Development of Cryogenic Targets for Laser Fusion

Abstract

In the development of targets for laser fusion, there is considerable interest in producing a uniform spherical shell of liquid or solid deuterium-tritium mixture (1:1 ratio). It is felt that fuel in this form, compressed and heated by laser beams, would give optimum energy yield [^1,2]. Fabrication of this target begins with selection of glass microballoons, 80 to 100 μm in diameter and 1 to 2 μm in wall thickness for uniformity in diameter and wall. These are filled by diffusion at 400°C and high pressure and rapidly cooled to room temperature to entrap the gas. Various fills have been used: D₂, T₂, and D—T, ending with 50 to 190 atm at 300 K, which result in upper condensation temperatures of 29 to 38 K. If all the fuel is condensed uniformly on the inner surface of the container, the solid layers are calculated to be 0.5 to 2.1 μm thick.

Work performed under the auspices of the U. S. Energy Research and Development Administration.