General Fusion develops diagnostic method for large-scale fusion machine

Wednesday 25 March 2026 - 08:20

By: Dakir Madiha

General Fusion develops diagnostic method for large-scale fusion machine

General Fusion, a Canadian company working toward the commercialization of nuclear fusion technology, announced the publication of a peer-reviewed study in Fusion Science and Technology. The paper introduces an innovative diagnostic method to measure ion temperatures in the Lawson Machine 26 (LM26), the world's first large-scale magnetized target fusion demonstration system.

The method involves neutron counting to evaluate ion temperature, a critical metric for fusion performance. LM26 aims to achieve ion temperatures of 1 keV (10 million degrees Celsius) to 10 keV (100 million degrees Celsius), a requirement to meet the Lawson criterion. This benchmark determines when fusion plasmas can generate net energy output.

Mike Donaldson, General Fusion's senior vice-president of technology development, noted that ion temperature is a vital performance indicator for LM26. He emphasized that neutron counting offers a practical method for temperature measurement, which will validate plasma performance as the machine approaches target temperatures.

The diagnostic techniques build on existing work with PI3, the world's largest operational plasma injector, now integrated into LM26. The machine’s broader diagnostic suite includes magnetic sensors, spectroscopy, laser systems, and ultraviolet diodes to measure electron temperatures, ensuring comprehensive performance monitoring.

The LM26 achieved its first magnetized plasma early in 2025, just 16 months after its design and assembly began. Since then, daily plasma production highlights its progress toward the next milestone: compressing plasma with a lithium enclosure to initiate fusion heating. Operated at half the diameter of a commercial facility, this prototype demonstrates General Fusion’s unique approach, which relies on mechanically compressing magnetized plasma instead of superconducting magnets or high-powered lasers found in competing designs.

These advancements come at a pivotal moment for General Fusion as it works toward becoming the first publicly traded company focused exclusively on nuclear fusion. In January 2026, the company announced a definitive merger agreement with Spring Valley Acquisition Corp. III, valuing General Fusion at approximately $1 billion. The transaction includes $230 million from SVAC’s trust and $105 million from an oversubscribed private placement. The merger is expected to conclude mid-2026, with General Fusion debuting on the Nasdaq under the ticker "GFUZ."