Frequencyhyphen;dependent absorption efficiency and neutron production in lowhyphen;energy laser irradiation of slab targets

摘要

A series of numerical experiments have been performed to examine the efficiency of the coupling of laser energy into a plasma target. Classical inverse bremsstrahlung absorption is considered in both the weakhyphen; and stronghyphen;field limits at laser intensities from sim; 1015to sim; 1016W cmminus;2at the fundamental and first harmonic neodymium laser frequencies. Frequency multiplication from the fundamental to the harmonic is shown to lead to desirable results even if the conversion efficiency is low. The computed absorption, xhyphen;ray generation, and neutron production are compared with experimental results. Nonthermal mechanisms are discussed to account for the result that much larger neutron production is found experimentally than can be accounted for in a numerical model.