Energy · Fusion Record
Fusion Energy Gain
The best energy gain any fusion experiment has achieved: past scientific breakeven in 2022, and setting records almost yearly since.
- Q 0.12 → 4.13 since 1991
- Breakeven: Q 1.51 in December 2022
- Two bases: tokamak power, laser energy
- Wall-plug gain still ~0.02 — no power source yet
The record line for controlled fusion’s central number: Q, energy out over energy in, the best value achieved by any experiment on Earth. Two eras, two definitions. The peer-reviewed compilation this series comes from keeps them distinct, and so does this chart. The tokamak era is power gain, fusion power over heating power at the pulse’s peak: JET opened the compiled line at 0.12 in 1991, TFTR pushed it to 0.28, and JET’s 0.63 in October 1997 closed the tokamak record book — no magnetic machine has beaten it since, a silence ITER was built to end. (A TFTR record from December 1993 is real but its value and date cannot be pinned to a primary source, so the gap stays a gap.)
The laser era is energy gain, fusion yield over laser energy delivered to the target: NIF’s burning plasma reached 0.69 in August 2021, and on 5 December 2022 it returned 3.15 MJ from 2.05 MJ of laser light — logged by the compilation as a gain of 1.51, the first controlled fusion reaction to give back more energy than was put in. Records have come almost yearly since: 1.89, then 2.36, then 2.44, then the standing 4.13 (8.6 MJ from 2.08 MJ in April 2025).
One number is deliberately absent: wall-plug gain. NIF’s lasers draw a few hundred megajoules of electricity per shot, so even the record shot returned roughly 0.02 of the energy the facility drew. Fusion has crossed scientific breakeven, not engineering breakeven, and that distinction is the headline. The flat right-hand end is measured, not missing: the most recent ignition, in June 2026, reached 7.9 MJ and did not take the record.
| Year | Value | Note | Projected |
|---|---|---|---|
| November 1991 | 0.12 | JET: the first compiled D-T gain | |
| May 1994 | 0.28 | ||
| October 1997 | 0.63 | JET: the last tokamak record (power basis) | |
| August 2021 | 0.69 | NIF: burning plasma — the metric changes hands (energy basis) | |
| December 2022 | 1.51 | NIF: scientific breakeven — more energy out than laser in | |
| July 2023 | 1.89 | ||
| February 2024 | 2.36 | ||
| February 2025 | 2.44 | ||
| April 2025 | 4.13 | NIF: 8.6 MJ from 2.08 MJ, the standing record |