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 glass 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 of the shell is coated with high-Z material⁵ (Fig. 1). For production of direct drive targets, manufacturing techniques have been developed for both hollow glass and polystyrene microspheres. Hollow glass microspheres 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 glass microspheres with diameters from 50 µm to 1 mm, wall thicknesses from 0.5 to 10 µm, 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 µm and wall thicknesses from 1 to 10 µm.