Scientists at the California-based lab repeated the fusion ignition breakthrough in an experiment in the National Ignition Facility (NIF) on July 30 that produced a higher energy yield than in December, a Lawrence Livermore spokesperson said. Lawrence Livermore achieved a net energy gain in a fusion experiment using lasers on Dec. 5, 2022. That experiment briefly achieved what's known as fusion ignition by generating 3.15 megajoules of energy output after the laser delivered 2.05 megajoules to the target, the Energy Department said.