Core performance in direct-drive spherical implosions on OMEGA

Summary form only given, as follows. The achievement of high-density compressed cores using the 60-beam OMEGA laser system to implode cryogenic DT targets is an important milestone on the path to direct-drive ignition. The paper reviews the cryogenic designs for OMEGA and show the scaling to ignition designs for the NIF. Results from the first series of cryogenic implosion experiments and surrogate, gas-filled, plastic shell implosion experiments are presented. A wide range of nuclear and spectroscopic diagnostics have been applied to the surrogate implosions, which has resulted in the development of a highly constrained model of the core conditions and fuel-shell mix. The recent improvement in target performance with improved single-beam uniformity are described in detail. 1 THz- bandwidth, 2-D smoothing by spectral dispersion (SSD) and polarization smoothing (PS) using birefringent wedges have reduced the on-target nonuniformity to less than 1% when averaged over 300 ps. Targets imploded using this improved beam smoothing show significant performance improvements over targets imploded with a third of the bandwidth and no PS. These targets have similar acceleration-phase stability as ignition-scaled implosions proposed for the NIF. They produce /spl sim/40% of their predicted 1 D neutron yield and nearly 100% of their predicted fuel and shell areal densities.