NIF fusion yield

In 2025 the National Ignition Facility in California produced 8.6 megajoules of fusion energy from about 2 megajoules of laser light, over four times what went in. It first reached ignition in December 2022.

Context

The National Ignition Facility fires 192 laser beams at a tiny fuel capsule held inside a gold cylinder. The beams heat the cylinder, which produces X-rays that squeeze the capsule so hard that hydrogen isotopes fuse and release energy. Ignition means the fusion energy released is greater than the laser energy delivered to the target.

The first such result came on 5 December 2022, when about 3.15 megajoules came out for roughly 2.05 megajoules of laser light. Later shots improved on it, and the 2025 shot with 8.6 megajoules is the highest reported so far, according to the laboratory.

The comparison counts only the laser light that reaches the target. The lasers draw far more electricity from the grid than that, so the facility does not produce net power as a power plant would. The experiments are mainly meant for research into nuclear weapons physics and fusion science, and each shot needs a long preparation time. Scientists describe these results as a proof of principle for inertial confinement fusion, not as a working design for a power station, which would need far higher repetition rates and efficiency.