The company is positioned for success, and is making strong progress towards achieving commercial fusion energy
The Fusion Report recently had an opportunity to interview Dr. David Kirtley, the founder and Chief Executive Officer (CEO) of Helion Energy. Prior to founding Helion Energy in 2013, David served as a principal investigator, fusion research leader, and propulsion lead at Mathematical Science Northwest (MSNW). Before that, David was a research scientist at the Air Force Research Laboratory at Wright-Patterson Air Force Base in Dayton, Ohio, while concurrently working as a graduate student researcher at the University of Michigan Plasma Dynamics Laboratory. Before we get into the interview, we’ll discuss Helion Energy’s long-term approach to commercial fusion energy, which is fairly unique.
Helion Energy’s Long-Term Approach to Fusion Energy
Helion Energy is pursuing a compact, pulsed form of magneto-inertial fusion rather than the large, steady-state tokamak approach used by many public fusion programs. Its machines create two field-reversed configuration (FRC) plasmas—self-organized rings of hot plasma confined by magnetic fields—then accelerate them toward one another, merge them, and rapidly compress the resulting plasma with magnetic fields. The compression is designed to raise plasma conditions to fusion energies and temperatures, where a fusion reaction between deuterium and helium-3 (D-He3) can occur. While D-He3 requires higher temperatures than deuterium-tritium (D-T) fusion, its main reaction is aneutronic (i.e., it produces no neutrons). Also, rather than requiring a plasma to remain self-sustaining through ignition, Helion aims to repeat short pulses at high frequency; in principle, output can be adjusted by changing the pulse rate.
A second defining feature is Helion’s use of direct electricity recovery (DER), rather than a conventional thermally-based electricity generation cycle (steam turbines plus generators). D–He3 fusion produces energetic charged particles, allowing the expanding post-pulse plasma to push against the generator’s magnetic field and induce current in surrounding coils—an effect Helion compares with regenerative braking in an electric vehicle. This is meant to avoid the conventional chain of fusion heat, steam production, turbine rotation, and electrical generation, reducing conversion losses and plant complexity. The fuel cycle is also intended to reduce neutron production compared with deuterium–tritium fusion, potentially easing some material degradation, material activation, and shielding challenges. However, Helion’s approach (like all other commercial fusion energy companies) must still demonstrate reliable high-repetition operation, favorable net plant energy balance, durable components, and a practical helium-3 fuel supply at commercial scale.
On the positive side, Helion signed a power-purchase agreement in 2023 to provide Microsoft with electrical power. Helion plans to supply electricity from its planned Orion plant in Chelan County, Washington, beginning in 2028, with at least 50 MW delivered after an initial ramp-up. Constellation Energy is designated as the project’s power marketer, meaning it will handle the commercial/grid-market role associated with the electricity transaction. The project is intended to connect to the regional grid near Microsoft’s central Washington data-center operations, rather than being a dedicated behind-the-meter supply line. Helion also has a 2023 collaboration with steelmaker Nucor to deploy a proposed 500 MW fusion power plant supplying zero-carbon electricity directly to a Nucor steelmaking facility in the United States. Helion has characterized this as a customer agreement and development collaboration. Nucor also invested in Helion as part of the arrangement.
The Fusion Report’s Interview With David Kirtley (9/24/26)
The Fusion Report: So let’s get the obvious question out of the way. What caused the delay of Helion’s schedule, and how comfortable/confident are you with your new schedule?
David Kirtley: This wasn’t so much a delay as a misunderstanding, which I have seen incorrectly reported, even when we first announced the PPA. We didn’t have a milestone that said, “On day one, we are going to go to full power and produce energy,” or anything along those lines; a lot of work has to be done before you are ready to get to that point. A first of a kind technology takes some time to commission. That was built into the agreements with Microsoft and internal plans; we build the buildings, we build the technology, we start operating, and with time, we can ramp up to full power.
The Fusion Report: You have chosen deuterium-helium3 (D-He3) fusion as your long-term approach because it is aneutronic, and because it enables direct electricity conversion. How far are you proving D-He3 fusion’s viability, as well as the ability to breed helium3?
David Kirtley: Our deuterium-helium3 (D-He3) fusion validation starts out with deuterium-deuterium (D-D) fusion and with deuterium-tritium (D-T) fusion. We have been a leader in D-D fusion, first demonstrating D-D neutron production achieving it in 2011. Our goal is not to show that D-D fusion was realistic (the energy output is not high enough given the temperatures required); our goal, which was successfully achieved, was to show that helium3 can be made from D-D fusion. Earlier this year, we were the first private company to successfully demonstrate D-T fusion, proving the operation of our Polaris fusion machine. This was preparation testing for our D-He3 testing, first on Polaris, and then on Orion, once we achieve the required temperatures and pressures.
The Fusion Report: One of the coolest things about your approach is the use of direct electricity conversion (DEC). How efficient do you think DEC will be in converting fusion energy into electricity, and how much better is it than the conventional thermal approach to electricity generation?
David Kirtley: Great question. Our theoretical research shows that we should be able to get up to 90% efficiency in converting charged particles (which is primarily where the energy from aneutronic fusion goes into) directly into electricity. Even if we were to get half that in practice, it would still be significantly better than thermal cycles using heat exchangers, steam turbines, and generators. That would be a game changer for our industry, especially given that our DEC system is solid state, as opposed to the spinning machines required in a thermal cycle system, which would also require significant maintenance over its lifecycle.
The Fusion Report: Your Orion fusion machine is fairly small, targeting 50 MWe. I assume that you plan on making larger follow-on reactors. Is there a practical limit to an FRC machine’s effective size/power output, and if so what is it?
David Kirtley: It’s actually interesting in that a 50MWe power plant is probably the lower limit that an FRC machine can be done at, which is one of the reasons we chose it as our initial milestone. As you can imagine, efficiency also scales with size, so the larger the system gets, the more efficient energy-wise and cost-wise the system gets. So to answer your question, we expect to build larger systems which would be significantly more efficient from a cost and energy perspective as they scale.
The Fusion Report: What will the next big milestone be for Helion Energy and for Orion?
David Kirtley: There’s three areas that we’re really concentrating on in the near future:
We’re still learning a lot from Polaris and we’ll continue utilizing it while Orion is under construction.
We’re completing Orion’s infrastructure in Malaga, Washington. We’re completing the last building and getting the substation ready for operation.
On the business side, we’re focused on streamlining the manufacturing of the fusion equipment – things like how reliably and how fast we can build them. I’m looking at build rates every day, making sure we can build the Orion equipment quickly and reliably.
Helion Energy’s Funding To Date
Helion Energy has raised $1.5 billion in invested capital to date, making it the second-highest private lifetime funding of any commercial fusion energy company globally. Helion’s funding culminated in an oversubscribed $500 million Series G round which closed in September 2026. The Series G was initially announced at $465 million in June, led by Thrive Capital, and placed the Everett, Washington fusion developer at a $15.5 billion post-money valuation—almost three times its $5.4 billion valuation after the $425 million Series F in January 2025. Helion’s investor base includes financial and strategic backers, including Lightspeed Venture Partners, SoftBank Vision Fund 2, Mithril Capital, Capricorn Technology Impact Funds, Good Ventures, Nucor, and new Series G participants such as Lux Capital, Peak XV Partners, BoxGroup, Alta Park Capital, Anti Fund, and Bill Ford, the executive chair of the Ford Motor Company. Earlier financing included a $500 million Series E in 2021, alongside up to $1.7 billion in milestone-linked commitments, although those commitments should not be treated as cash raised unless and until the relevant conditions are met.
Future financing options are likely to combine further late-stage private equity with project-specific and strategic capital rather than relying on a single source. Helion can return to existing and new crossover, pension, sovereign-wealth, and growth-equity investors—groups it said participated in the expanded Series G—as it funds construction of Orion, scales production at its Omega capacitor factory, and works toward supplying Microsoft under its agreement for at least 50 MW. The company could also pursue customer-backed project finance, strategic investments from industrial power buyers or equipment partners, government grants and incentives, equipment or manufacturing financing, and eventually an IPO if technical milestones and commercial revenue substantially reduce perceived risk. Its prospective $1.7 billion of contingent Series E commitments remains a potentially meaningful source of capital, but it is conditional, while the feasibility and cost of financing a first-of-a-kind fusion plant will depend heavily on Helion demonstrating repeatable performance, regulatory progress, construction execution, and credible delivery against its power-purchase agreement commitments.
Conclusion: Helion’s Outlook On Commercial Fusion Energy
Helion Energy successfully tested D-T fusion early this year, achieving a record temperature of 150 million °C. After an extended campaign of more D-T fusion testing occurs and higher temperatures are reached, Helion Energy will be ready to perform D-He3 testing on Polaris, and then on Orion. The Orion testing will include electricity generation, initially connecting to the grid by the end of 2028, and achieving 50MWe of output after a ramp-up and testing period. We wish Helion Energy good luck on their testing campaign and achieving this historic milestone!
