Imprint Efficiency Measurements in Laser-Driven Plastic Foils Using Beams with Different Angles of Incidence

90 LLE Review, Volume 98 Introduction The goal of the direct-drive approach to inertial confinement fusion (ICF)1,2 is to uniformly implode a spherical target with deuterium–tritium (DT) fuel using a large number of overlapped laser beams. A combination of high temperature and high areal density (ρR) in the DT fuel at peak compression is necessary to ignite the target and achieve high gain.1–3 The most-significant factor that limits the implosion performance is the unstable growth of target perturbations. As a result of this growth, the fuel temperature and compression may be reduced, leading to a reduction in the thermonuclear yield. The target perturbations in direct-drive ICF include existing imperfections of the inner and outer target surfaces and are dominated by modulations seeded (or imprinted) by the spatial laser nonuniformities;4–29 therefore, understanding and controlling laser imprinting are crucial to the success of direct-drive ICF.