ICF TARGET TECHNOLOGY AT THE RUSSIAN-FEDERAL-NUCLEAR-CENTER

The main effort of the ICF target fabrication group is support of the experiments performed on the ''ISKRA-4'' and ''ISKRA-5'' laser systems . The main types of targets used in these experiments are direct drive , inverted corona, and indirect drive. A direct drive target is a glas s spherical container coated with a metal or polymeric film and filled with a D-T mixture and some diagnostic gas.(1,2) The inverted corona target is a spherical shell with holes for introducing laser radiation . The inside surface of the shell is coated with a compound containing heavy hydrogen isotopes.(3,4) The indirect drive target is assembled from a spherical shell with holes for introducing laser radiation and a direct drive target placed in the shell center. The inside surface o f the shell is coated with high-Z material(5) (Fig. 1). For production of direct drive targets, manufacturing techniques have been developed for both hollow glass and polystyrene microspheres. Hollow glass micr ospheres are fabricated by free-fall of liquid glass drops or dry gel in a 4 meter vertical kiln.(6) These methods allow us to manufacture g lass microspheres with diameters from 50 mu m to 1 mm, wall thicknesse s from 0.5 to 10 mu m, and aspect ratios (radius/wall) from 20 to 500. The microspheres have a thickness inhomogeneity less than 5% and non- sphericity less than 1%. Polystyrene microspheres are fabricated from polystyrene particles with a blowing agent in a similar vertical kiln. Polystyrene microspheres are fabricated with diameter up to 800 mu m and wall thicknesses from 1 to 10 mu m.