New target designs for direct-drive ICF

We describe two approaches to the design of a direct-drive high-gain pellet for inertial confinement fusion reactors that has enhanced stability due t o the reduction in the Rayleigh-Taylor growth rate and enhanced thermal smo othing of laser imprint. The first design incorporates an overcoat containi ng a high-Z element that radiatively heats the ablator during the foot of t he laser pulse. The second incorporates a very low density foam ablator tha t is compressed by a series of transmitted and reflected shocks. Both desig ns enhance thermal smoothing by developing a very long density scale length and high electron densities in the ablator blowoff.