Helion Energy achieved two milestones in their race towards commercial fusion power: achieving measurable-deuterium-tritium fusion, and setting a new private fusion plasma temperature record of 150 million degrees Celsius (150M °C). Both milestones were achieved using Helion’s Polaris prototype fusion machine in their Everett, Washington headquarters. Announced last Friday in The Fusion Report weekly wrap-up, we provide a deep-dive into these achievements in today’s article.

“We believe the surest path to commercializing fusion is building, learning and iterating as quickly as possible,” said David Kirtley, co-founder and CEO of Helion. “We’ve built and operated seven prototypes, setting and exceeding more ambitious technical and engineering goals each time. The historic results from our deuterium-tritium testing campaign on Polaris validate our approach to developing high power fusion and the excellence of our engineering.”

Polaris is Helion's 7th generation fusion machine. It came online at the end of 2024, and follows their Trenta fusion machine. Polaris will be followed by Orion, Helion’s first production machine, whose facility is currently being built in Malaga, Washington. This facility will provide power to a Microsoft data center, in support of Helion’s first deal with them to provide Microsoft with 50 MW of commercial power.

“I am impressed with our nation’s ingenuity and the pace at which we are de-risking our path to fusion commercialization,” said Jean Paul Allain, Associate Director for Fusion Energy Sciences in the Department of Energy’s Office of Science. “Seeing the data from the Polaris test campaign, including record-setting temperatures and gains from the fuel mix in their system, indicates strong progress. Our ability to get fusion on the grid requires approaches that enable rapid turnaround in design and testing, and these results reflect the growing capability of the U.S. fusion ecosystem.”

One of the key differentiators between Helion's approach and that of other commercial fusion approaches is the use of direct drive power conversion. While other approaches convert the fusion energy into high pressure steam which then drives a turbine and generator like conventional power plants, Helion takes a different approach. Their solution bypasses the use of pressurized steam as in conventional approaches, and instead uses the “recoil” of the fusion reaction to generate currents in the machine’s magnets and generate electricity.

The other main differentiator between Helion and most other approaches is the use of aneutronic fusion. While deuterium-tritium (D-T) fusion requires the least amount of power to achieve ignition, and the fuel (two isotopes of hydrogen) are reasonably plentiful, most of the 17.6 MeV of energy generated by D-T fusion is high-energy neutrons, with each neutron carrying 14.1 MeV. These high-energy neutrons, in addition to needing to be “thermalized” (converted to thermal energy which can drive a turbine), also have the nasty habit of ‘activating’ materials in the fusion machine, making them radioactive. To completely avoid this requires the use of aneutronic fusion (fusion which releases charged particles rather than high-energy neutrons). While aneutronic fusion reactions require more energy (e.g., higher temperatures) than a D-T reaction does, using deuterium and helium-3 (D-He3) produces an essentially aneutronic (a fusion reaction that produces less neutrons, and whose neutrons are much lower energy), and with reasonable temperature requirements. While Helion will initially utilize deuterium-tritium fusion, it will over time switch over to deuterium-helium3 aneutronic fusion.

Conclusion: Progress in Turning on the Fusion Energy Solution

Electricity is by far and away the most sought after form of energy in the world today. Generating this electricity is required to power any number of solutions on our planet today from industrial, residential, commercial uses, to things like artificial intelligence (AI) and electric vehicles (EVs). Helion sees fusion reaching 10% or greater of the total US electricity generation quickly after launching their initial fusion electricity plant in 2028. We can only hope that they are correct, as the (clean) electricity that fusion will produce is desperately needed to meet our exponentially growing energy demands.