Helion Triples Valuation to $15.5B in Race to Power Microsoft's AI Data Centers with Fusion by 2028

New investors participating in the round include Alta Park Capital, Anti Fund, BoxGroup, Lux Capital, Peak XV Partners, and Ford Motor Company Executive Chairman Bill Ford . They join a roster of existing backers who doubled down on their investment, including Lightspeed Venture Partners, SoftBank Vision Fund 2, Mithril Capital, Capricorn Technology Impact Funds, Dustin Moskovitz (via his Good Ventures Foundation), and an unnamed university endowment .

Helion's previous $425 million round, announced in January 2025, was also closely tied to its commercial agreement with Microsoft . This consistent upward trajectory in funding contrasts sharply with the deep scientific uncertainty surrounding the company's core technology.

The Orion Plant and the Microsoft Power Purchase Agreement

The primary use of the new capital is to accelerate the deployment of Orion, Helion's first commercial fusion power plant in Malaga, Washington . Construction on the site began in July 2025, and the plant is the physical manifestation of a landmark power purchase agreement (PPA) with Microsoft.

Under the deal, Helion has committed to supplying at least 50 megawatts (MW) of clean fusion electricity to a Microsoft data center in Central Washington by 2028, with penalties for the startup if it fails to deliver on time . This PPA places extraordinary commercial pressure on Helion to not just demonstrate fusion, but to make it a reliable, grid-connected power source within two years. The proceeds from the Series G are explicitly earmarked to scale manufacturing capacity and support this commercial delivery .

Helion's Unconventional Technology: Skipping the Steam Turbine

What distinguishes Helion from almost every other fusion effort, including the massive international ITER project and rivals like Commonwealth Fusion Systems, is its approach to generating electricity. The company uses a pulsed, magneto-inertial fusion system that bypasses the traditional steam turbine entirely.

In a conventional power plant—whether coal, gas, nuclear fission, or most proposed fusion reactors—the energy heats water into steam, which then spins a turbine to generate electricity, losing significant energy in the conversion process . Helion's design is fundamentally different. The company's reactor fires two compact rings of plasma at each other at immense speed within a magnetic field . When the plasma rings collide and expand after fusion, their motion changes the reactor's magnetic flux. Per Faraday's Law of Induction, this change induces an electric current in the machine's coils, which is captured directly as electricity .

"Just like regenerative braking in an electric car, our system is built to recover all unused and new electromagnetic energy efficiently," the company states in its official FAQ . This direct energy capture claims a net efficiency of over 95%, a stark contrast to the approximate 33-40% efficiency typical of steam-based systems . Helion's seventh-generation prototype, Polaris, is designed to be the first machine to demonstrate net electricity from this process and recently achieved record plasma temperatures of over 150 million degrees Celsius—ten times hotter than the core of the sun .

The Specter of Skepticism Amid a Fusion Funding Wave

Despite the technical milestones, a cloud of scientific skepticism hangs over Helion's timeline. Some fusion experts have expressed doubt that Helion's approach is viable, partly because the company publishes infrequently in peer-reviewed scientific journals, making independent, rigorous validation of its claims difficult . No experimental reactor, including Helion's, has yet demonstrated net electrical power generation at the scale required for a commercial grid .

CEO David Kirtley has countered this critique by arguing that a working commercial plant will be the ultimate and only necessary proof . For comparison, rival Commonwealth Fusion Systems, a tokamak-based startup, recently touted five peer-reviewed papers validating its physics .

Helion's raise occurred during an unprecedented surge in fusion funding. Just days earlier, German laser-fusion startup Focused Energy closed a record-breaking $240 million Series A, and on the same week, stellarator developer Thea Energy announced a $100 million Series B . Other major moves in 2026 alone include a $450 million Series A for inertial-fusion company Inertia Enterprises and an $87 million convertible note for Type One Energy, a Bill Gates-backed startup pursuing a $250 million Series B at a roughly $9 billion valuation . ARPA-E, a U.S. government agency, also made its largest-ever concentrated investment in fusion with a $135 million commitment in April 2026 .

Why Big Tech and AI Are Fueling Fusion's Moment

The common thread connecting almost all new fusion investment is the projected energy demand from the AI industry. As data centers grow into gigawatt-scale campuses to train and run advanced AI models, tech companies face an existential need for sources of power that are both carbon-free and available 24/7, without the intermittency problems of wind and solar . Fusion promises to fit that profile perfectly: a nearly limitless, always-on, zero-carbon baseload power source.

Microsoft's deal with Helion is the most concrete example of this synergy, and reports indicate that OpenAI, co-founded by Helion chairman and investor Sam Altman, has also explored a PPA with the company . The Helion funding round is ultimately a bet that the company can overcome immense physics and engineering hurdles, not in the 2030s like most of its peers, but in under three years. The $15.5 billion valuation will either be remembered as a prescient prediction or a peak of inflated expectations.