The pellet outran the laser, not the power plant
On 5 December 2022 a fusion target at the National Ignition Facility released 3.15 megajoules, more than the 2.05 megajoules of laser light that hit it. The building used far more energy than the pellet returned.
One hundred and ninety-two laser beams crushed a peppercorn of deuterium and tritium. For the first time in this kind of experiment, fusion reactions in the fuel returned more energy than the laser energy delivered to the target. The yield was about one and a half times the light that arrived. That is the National Academies’ definition of ignition for this program, and the paper says so.
Making the laser pulse consumed on the order of a hundred times more energy than the pulse carried. The lasers were built to answer a physics question, not to run a grid. A plant would need shots that repeat, targets that are cheap, and a gain measured from the wall socket, not from the last mirror. None of those were the claim, and none of them were demonstrated that day.
Caveats
- Target gain above one is not net electricity. Quoting 3.15 against 2.05 and stopping there leaves out the building.
- Later shots have varied. One result is not a reactor.
Sources
- 1Abu-Shawareb H. et al.. Lawson Criterion for Ignition Exceeded in an Inertial Fusion Experiment. Physical Review Letters 129, 2022.