Present status of direct drive inertial confinement fusion research at ILE Osaka University

Summary form only given. Direct drive implosion experiments at ILE of Osaka University are focused on planar and spherical target experiments relating to Rayleigh-Taylor instability and implosion experiments of cryogenic targets with low-density plastic foam shell overcoated by a solid plastic layer. To determine the value of /spl beta/ experimentally, planar plastic targets with well-controlled areal density modulation have been irradiated by a partially coherent green laser beam through focusing optics with a random phase plate (RPP) in order to have high illumination uniformity. The /spl beta/ value has been measured to be 3-4, as predicted by theory. In the spherical shell target implosions, a very early X-ray emission has been observed at the center of the target. The appearance of this pre-emission is related to the illumination nonuniformity. A high-quality low-density plastic foam shell with a solid plastic layer has been developed to be used as a capsule of cryogenic deuterium (or deuterium-tritium) fuel. Three states of deuterium, i.e., solid, liquid and gas, have been imploded under well-controlled conditions. The observed D-D neutron yields are 1-3/spl times/10/sup 6/ for the solid-state target and 3/spl times/10/sup 7/-2/spl times/10/sup 8/ for the gas and liquid targets.