General Fusion heated its plasma past 1 keV by squeezing it — and the UK's fusion lab put its name on the measurement

General Fusion said on 8 October that its Lawson Machine 26 compressed a magnetized plasma to electron temperatures above 1 keV — about 12 million °C — with meaningful ion heating. The temperature was measured using Thomson scattering and absolute extreme-ultraviolet diagnostics, and the results were co-published by the UK Atomic Energy Authority, the UK's national fusion laboratory. It follows a 0.72 keV compression result in June. The company calls it the first of three LM26 technical milestones; the next target is 10 keV, and upgrades for higher compression ratios are under way. General Fusion, which listed on Nasdaq this year, describes itself as a development-stage company with no revenue and aims to operate a first plant around 2035. A paper on the result has been submitted for peer review. The tracker records it.

Why it matters

Two things are true at once, and the headlines mostly carried only one. 1 keV is low by fusion standards — tokamaks routinely run ten to twenty times hotter, and the fusion temperature record in this tracker is in the hundreds of millions of degrees. If the question were "how hot can a fusion machine get", this would not register.

The question it answers is different: can magnetized target fusion — heating plasma by mechanically squeezing it with a liner, instead of using large superconducting magnets or lasers — actually heat plasma by compression the way its physics says it should? General Fusion's case for being cheaper than its rivals rests entirely on yes. Going from 0.72 keV in June to above 1 keV, with ion heating, is evidence for yes, and having a government laboratory co-publish the measurement is stronger than the company's word alone. It is not yet peer reviewed, and 10 keV is the step that would make the approach look like a contender rather than a demonstration.

There is one more thing to keep in view. General Fusion went public through a merger this year, and this tracker has an open watch item on the reliability of its pre-merger financial statements. A technical result co-signed by UKAEA is the kind of disclosure that does not depend on those statements, which is worth something for a listed company with no revenue.

What to watch

Publication of the peer-reviewed paper, the first LM26 results at higher compression toward 10 keV, and General Fusion's next financial filing.