Reduction of the Ablative RayleighTaylor Growth Rate with Gaussian Picket Pulses

LLE Review, Volume 95 139 Introduction The compression of an inertial confinement fusion (ICF)1 target must achieve high hot-spot temperatures (T 10 keV) and shell areal densities (rR 300 mg/cm2) to ignite. An ICF implosion is subject to the Rayleigh–Taylor (RT)2,3 instability as the shell accelerates inward and as the shell decelerates toward stagnation, causing small perturbations in the shell of the target to grow, potentially reducing the ultimate temperatures and areal densities. This instability can be mitigated two ways: reduction of the seed perturbation amplitudes and reduction of the RT growth rate. Much effort has gone into reducing the seeds of the RT instability due to the roughness of the inner and outer surfaces of the shell, as well as increasing the uniformity of the laser illumination or driving radiation. In this article, we report on the first observations of reduced RT growth rate using a prepulse or picket pulse4,5 preceding a main laser-drive pulse in planar-target experiments.