Direct-drive implosion experiments on the SG-II laser facility

SG-II, a 8-beam Nd:glass laser with an output energy capability of 6kJ at 1.053 mum, was built and direct-drive implosions were successfully performed early in 2000. Both exploding pusher and ablative targets were imploded using glass capsules with diameters of 200 and 500 mum, and a wall thickness of about 1 mum. The deuterium and tritium (DT) gas pressure filled in these capsules were 2.0 and 0.5MPa, respectively. Sophisticated diagnostics were deployed to measure laser absorption, hot electron temperature and fraction, thermal electron temperature, neutron yields, ion temperature, temporally resolved x-ray images, fuel areal density, alpha particle image, and so on. Significant results, such as neutron yields up to 4 x 10(9) for exploding pushers with 100-ps laser pulse irradiation and 6 x 10(8) for ablative targets with 1-ns pulses and clear x-ray images to see the compression process, were obtained. Numerical simulations were conducted to optimize target and laser parameter design and to duplicate the results afterwards with the specific shot parameters used in the experiment.