General Fusion Inc. announced a peer-reviewed publication in Fusion Science and Technology journal detailing a diagnostic system for measuring ion temperatures in its LM26 fusion demonstration machine. The Vancouver-based company plans to go public through a business combination with Spring Valley Acquisition Corp. III (NASDAQ: SVAC).

The research outlines a method using neutron counting to measure ion temperatures in General Fusion's Magnetized Target Fusion approach. The LM26 machine targets temperatures of 1 keV (10 million degrees Celsius) and 10 keV (100 million degrees Celsius) as it works toward achieving the Lawson criterion for net fusion energy production.

"Ion temperature is a key parameter for fusion performance in our LM26 program," said Mike Donaldson, Senior Vice President of Technology Development at General Fusion. "Our work demonstrates a practical, scalable method to measure ion temperature using neutron counting."

The LM26 system incorporates multiple diagnostic tools including neutron detectors, magnetic sensors, spectroscopy, and laser-based systems. Temperature measurements will also use extreme ultraviolet diodes for electron temperature analysis. The machine builds on technology from PI3, described as the world's largest operational fusion plasma injector.

General Fusion began operating LM26 in early 2025, calling it the first MTF demonstration machine at commercially relevant scale. The system mechanically compresses plasma using a lithium liner at 50% commercial-scale diameter. The company, established in 2002, has over 20 years of experience in fusion prototype development.