LASER DESIGN BASIS FOR THE NATIONAL-IGNITION-FACILITY

Controlled nuclear fusion initiated by highly intense laser beams has been the subject of experiment for many years. The National Ignition F acility (NIF) represents the culmination of design efforts to provide a laser facility that will successfully demonstrate fusion ignition in the laboratory. In this so-called inertial confinement approach, ener getic driver beams (laser, X ray, or charged particle) heat the outer surface of a spherical capsule containing deuterium and tritium (DT) f uel. As the capsule surface explosively evaporates, reaction pressure compresses the DT fuel causing the central core of the fuel to reach e xtreme density and temperature. When the central temperature is high e nough, DT fusion reactions occur. The energy released from these react ions further heats the compressed fuel, and fusion burn propagates out ward through the colder regions of the capsule much more rapidly than the inertially confined capsule can expand. The resulting fusion react ions yield many times more energy than was absorbed from the driver be ams. Figure I summarizes the inertial confinement fusion (ICF) process .