General Fusion reported on 8 October 2026 that its Lawson Machine 26 (LM26) demonstration reached electron temperatures of 1.1 keV, or 12.6 million degrees Celsius, using its Magnetised Target Fusion approach. The measurement, made just before peak compression using Thomson scattering, was co-authored by the UK Atomic Energy Authority (UKAEA) and submitted for peer review. According to the announcement, LM26 is the first fusion machine to reach 1 keV with low-speed compression, a result the company says only a few fusion companies have achieved, all using other approaches.

UKAEA said its diagnostic specialists worked with General Fusion to design and commission a Thomson scattering system able to measure plasma enclosed in a metal liner and compressed to a very small volume. A key component, a polychromator, was built at UKAEA's Diagnostic Innovation Centre of Excellence at Culham Campus. UKAEA CEO Dennis Whyte called hot electrons a necessary step for proving fusion confinement concepts.

General Fusion said upgrades to LM26 were underway to support higher compression ratios, with a next targeted milestone of 10 keV, before work toward the Lawson criterion. It described the programme as designed to de-risk the path to a first-of-a-kind plant, with a goal of beginning operation around 2035. The company cited more than two decades of development in Canada and long-standing collaboration with UKAEA.