Update: On November 2nd, 2025 this paper was published in Physics of Plasmas and is open access.
Today we’ve released a pre-publication version of an update to our 2022 paper “Progress toward fusion energy breakeven and gain as measured against the Lawson criterion.”
Included in the update are plots with new results from eight experiments and a new plot of achieved scientific energy gain Qsci over time. We plan to submit this paper to the journal Physics of Plasmas in early June. In the meantime, we welcome comments, corrections, and additional significant data for inclusion in the paper from interested readers.
Much has happened in the physics progress toward fusion energy breakeven and gain over the past three years! But the whole picture comes into focus by animating progress over the past seventy.
In the animation above, the red contours show what’s needed to achieve the indicated values of scientific energy gain for magnetic confinement fusion (MCF) experiments. The black curve shows what’s needed to achieve hot-spot ignition and the onset of propagating burn in inertial confinement fusion (ICF) experiments.
Also updated is our plot of record triple product versus year for each concept.
There’s also been progress beyond what’s shown on these plots. Because ICF results that have achieved ignition “graduate” from these plots, we’ve created a new plot of scientific energy gain Qsci versus date achieved, which include recently publicized results from the National Ignition Facility (NIF).
The recent NIF achievements appear prominently on this plot, as performance has increased rapidly beyond their first achievement of scientific energy breakeven Qsci>1 in late 2022 (arguably the most significant milestone in ~70 years of controlled-fusion research).
This all points the way to more efforts to increase Qsci and sustainment (which means longer pulse durations in MCF and laser/target technologies to enable increasing repetition rate in ICF). Fusion companies all have their eyes on these challenges.
More detailed descriptions of each of these plots and other updates to the original paper are included in the preprint – please send your comments and feedback to [email protected]!