Optimization of irradiation configuration using spherical t-designs for laser-direct-drive inertial confinement fusion

Abstract

A new class of beam configurations is proposed for symmetric-direct-drive inertial confinement fusion laser systems. These configurations are based on spherical t-designs that are studied in spherical design theory in mathematics [P. Delsarte et al., Geometriae Dedicata 6, 363 (1977)]. Employing t-design configurations offers elimination of spherical-harmonic intensity modulations for modes ℓ ≤ t. Additionally, these configurations provide fast decay of intensity nonuniformities with increasing number of beams and symmetric intensity patterns on the surface of the target. Methods developed in spherical design theory offer a convenient, systematic way of obtaining beam configurations for an arbitrary number of beams.