Although their initial campaign to achieve a sustained fusion reaction formally ended unsuccessfully more than two years ago, researchers at the National Ignition Facility (NIF) have continued to narrow the gap between best current results and their goal. Recent experiments have come within a factor of three of the parameter conditions—some combination of pressure, confinement time, and temperature, among other conditions—that are believed to be required for ignition, says John Edwards, the inertial confinement fusion program director at NIF host Lawrence Livermore National Laboratory. NIF’s initial result was within a factor of 10 when the first campaign ended in September 2012 (see Physics Today,June 2013, page 20). Ignition is defined as the point at which the net fusion yield equals or exceeds the incident laser energy.
Now that they have significantly increased their understanding of the process of imploding the fusion fuel capsule, NIF scientists are turning their...
