Irradiation uniformity and zooming performances for a capsule directly driven by a 32×9 laser beams configuration

An inertial confinement fusion capsule directly driven by laser beams has been considered. A ray-tracing package is used to evaluate the uniformity of the energy deposition and the absorption efficiency provided by the direct irradiation of the capsule. Two distinct configurations with a single laser beam or a bundle of nine laser beams associated to 32 directions of irradiation are considered. Assuming a beam-to-beam power imbalance of 5% and a super-Gaussian spatial profile of the beams intensity, is found that the configuration using the bundles provides better irradiation uniformity. The laser beams of each bundle have been divided in two groups of four and five beams with associated different focal spots in order to increase the laser-capsule coupling efficiency. A configuration saving 16% of the laser energy and limiting the irradiation nonuniformity to less than 1% has been individuated.