Helion reaches 150 million degrees in private fusion milestone

13:40

By: Dakir Madiha

Helion reaches 150 million degrees in private fusion milestone

Helion Energy said its Polaris prototype reactor has achieved plasma temperatures of 150 million degrees Celsius and demonstrated measurable deuterium tritium fusion, marking a first for a privately developed fusion machine. The company described the breakthrough as a significant step toward its goal of delivering commercial fusion power to Microsoft by 2028.

The Washington state based startup began operating its seventh generation Polaris prototype in late 2024. In January, it became the first private fusion company authorized to possess and use tritium fuel for a commercial energy demonstration, clearing a regulatory hurdle that allowed it to proceed with deuterium tritium testing.

Reaching 150 million degrees surpasses Helion’s previous industry record of 100 million degrees Celsius, achieved with its sixth generation Trenta prototype. In the fusion sector, 100 million degrees is widely regarded as the minimum plasma temperature required for a commercially viable reactor.

David Kirtley, Helion’s co founder and chief executive, said the company’s approach centers on rapid development cycles. He said the deuterium tritium test campaign on Polaris confirmed both the engineering design and the path toward high power fusion systems.

Ryan McBride, a specialist in inertial confinement fusion and former department director at Sandia National Laboratories who also taught at the University of Michigan, said he reviewed Helion’s diagnostic data. He described the evidence of deuterium tritium fusion and temperatures above 13 keV, equivalent to 150 million degrees Celsius, as an encouraging development.

Helion’s reactor is based on a field reversed configuration design. Fuel is injected at both ends of an hourglass shaped chamber and converted into plasma. Magnetic fields accelerate the two plasma streams toward each other. When they collide, additional magnetic compression rapidly increases the temperature to 150 million degrees in less than a millisecond, according to TechCrunch.

Kirtley said the company ultimately aims to reach 200 million degrees Celsius to support optimal commercial performance. Although Polaris currently operates with deuterium tritium fuel, Helion plans to transition to deuterium helium 3 for commercial plants. That fuel mix produces more charged particles, which aligns with the company’s strategy of converting fusion reaction energy directly into electricity rather than using heat to drive turbines.

Jean Paul Allain, associate director for fusion energy sciences at the US Department of Energy’s Office of Science, said the results signal meaningful progress and reflect the growing capability of the American fusion ecosystem.

Construction is underway on Helion’s first commercial power plant, known as Orion, in Malaga, Washington. Work on the facility began in July 2025. The company has signed a power purchase agreement with Microsoft to supply at least 50 megawatts of fusion generated electricity by 2028. Constellation Energy will act as the energy marketer for the project.