Imprint Reduction Using an Intensity Spike in OMEGA Cryogenic Targets

56 LLE Review, Volume 82 The primary obstacle to the successful implosion of an inertial confinement fusion target is hydrodynamic instability, which can cause the target to disintegrate and prevent it from reaching the high densities and temperatures required for ignition. The imploding target is primarily subject to the Rayleigh–Taylor (RT) instability, seeded by surface nonuniformity and by laser illumination nonuniformity, which can imprint itself on the target surface. Efforts to reduce laser imprint have employed primarily smoothing mechanisms such as smoothing by spectral dispersion (SSD),1 distributed polarization rotators (DPR’s),2 and distributed phase plates (DPP’s).3 We present here a novel technique to further reduce imprint in OMEGA cryogenic (cryo) targets by a relatively simple modification to the standard pulse shape.