The Impact of Picket Timing and Picket Energy in Direct-Drive DT Cryogenic Implosions on OMEGA*

The performance of laser-direct-drive cryogenic DT inertial confinement fusion implosions depends on the timing of the shocks through the ablator and the DT ice shells launched by features in the laser pulse shape such as the short picket at the start of the pulse. These shocks set up the adiabat (plasma pressure over Fermi-degenerate pressure) distribution in the DT ice, which affects both its compressibility and the growth of hydrodynamic instabilities. A series of experiments has been performed systematically varying both the timing of the picket with respect to the rest of the laser pulse from -100 ps to +200 ps from its nominal value in steps of 100 ps and the energy in the picket by ±40%. A detailed comparison of the experimental observables from both neutron and x-ray detectors with the theoretical modeling will be presented.