Progress in hydrodynamics theory and experiments for direct-drive and fast ignition inertial confinement fusion

Recent advances in hydrodynamics theory and experiments at the Laboratory for Laser Energetics are described. Particular emphasis is laid on improvements in the implosion stability achieved by shaping the ablator adiabat and on the newly developed designs for fast ignition fuel assembly. The results of two-dimensional simulations and a recent set of implosion experiments on OMEGA are presented to verify the role of adiabat shaping on the hydrodynamic stability of direct-drive implosions. Adiabat shaping laser pulses are also used to implode massive capsules on a low adiabat and low implosion velocity in order to assemble high density plasmas for fast ignition. The areal densities measured in implosion experiments of such targets on OMEGA are among the highest ever recorded in a laser-driven compression experiment. Slow low-adiabat implosions of massive wetted-foam DT capsules are used in the simulations to generate the fuel assemblies for different driver energies. Such dense cores are then ignited by a fast electron beam and the resulting thermonuclear yield is used to compute the target gain. It is shown that a 200 kJ UV laser can assemble fuel yielding about 18 MJ of energy when ignited by 15 kJ of 1-2 MeV electrons.