Helion hits 150 million degrees, but fusion's real race is over who gets to the grid

Helion's facility in Everett, Washington, produced a headline number: 150 million degrees Celsius. That is 50 percent above the 100 million degrees reached by the company's sixth-generation Trenta prototype. It is the figure Helion used to claim an industry record. In its own announcement, the company said Polaris also became the first private fusion machine to demonstrate measurable deuterium-tritium fusion. No other private company has done that.

Two details matter more than the temperature. Helion says Polaris began operating at the end of 2024, and that the D-T campaign ran this January. The company also says it was the first to receive regulatory approval to possess and use tritium for fusion demonstration.

Those are not physics results. They are the paperwork and hardware that decide whether a machine can run at all. The public comparison remains ITER in southern France, which CNET described in May as the world's largest fusion reactor at an estimated cost of $22 billion. ITER's doughnut-shaped vacuum chamber is designed to hold plasma at 150 million degrees Celsius, the same temperature Helion now reports, with superconducting magnets kept a few degrees above absolute zero. Cracks in the heat shield piping turned up in 2020. Welding distortions and COVID-19 disruption followed, pushing the schedule back by years and adding $5 billion to repair costs.

"This is a publicly funded project," said Javier Artola, a scientist modelling ITER's plasma behavior. "It is the knowledge of the world."

That framing is not spin. ITER's member states, more than 30 countries, get access to the science, and the project has been building a global supply chain for fusion components. Laban Coblentz, ITER's chief strategic advisor, told CNET that the collaboration between China, Russia, the US, Europe, Korea, India and Japan was "either genius or insane." Private companies benefit from every problem ITER solves first.

Efficiency, not temperature

Realta Fusion went after a different bottleneck. On 19 June 2026, working with the University of Wisconsin-Madison on the WHAM mirror device, Realta demonstrated direct energy conversion of plasma kinetic energy into electricity. The company called it a first for a commercial fusion company. The converter sits on the end-ring assembly and slows charged particles leaving the mirror's loss cone through an electrostatic potential, turning their kinetic energy into current. Realta says the prototype draws multiple amps at around 100 volts, enough to light a few bulbs.

The company is explicit about the limits. This is not net electricity production, and it is not large-scale conversion of fusion-born power. WHAM runs on deuterium only. Realta's reasoning is that in a deuterium-tritium plant, 80 percent of the yield arrives as neutrons and 20 percent as charged alpha particles. Capturing the alpha power directly avoids pushing all of it through a thermal cycle.

The magnet problem and the money

Thea Energy, spun out of Princeton University and Princeton Plasma Physics Laboratory in 2022, raised $100 million in Series B funding on 27 May 2026, led by Thomas Tull's US Innovative Technology Fund. The company builds stellarators, an architecture whose twisted magnets were historically impractical to manufacture. Gaetano Crupi of USIT said Thea's approach shifts complexity from precision mechanical fabrication to software-defined controls. Thea plans a second magnet facility in northern New Jersey, will select a site for its Eos integrated stellarator later this year, and is targeting construction of its first Helios power plant before the end of the decade.

Helion, meanwhile, began building on the site of Orion, its first commercial machine, in Malaga, Washington, in July 2025. The plant is meant to deliver fusion electricity to the grid for Microsoft. That is the milestone that will settle the argument. Temperatures and converters are necessary. A signed offtake and a working plant are the test.