Helion says its seventh-generation Polaris machine has heated plasma to 150 million degrees Celsius using deuterium-tritium fuel, a milestone the company is pitching as a turning point in the race to commercial fusion. Backed heavily by Sam Altman, the startup is using the result to bolster its promise to deliver electricity to the grid by 2028. Chief executive David Kirtley called the achievement a critical step on the path to net energy, while independent experts caution that the hardest engineering and economic hurdles still lie ahead.
The Plasma Milestone
In a recent announcement, the Company said its seventh-generation prototype, Polaris, achieved plasma temperatures of “150 million °C” while operating with deuterium-tritium fuel, which Helion describes as an industry-first for a privately funded fusion machine. The firm framed Polaris as a pulsed prototype that fires rapid bursts of plasma rather than running continuously, arguing that this approach lets engineers iterate quickly on performance and component durability. In the same statement, CEO David Kirtley and his team cast the temperature result as direct progress toward net electricity generation, even though they did not disclose detailed energy balance numbers.
Helion’s announcement emphasizes that the 150 million degree figure is not just a physics bragging right but part of a staged roadmap from early prototypes to future commercial units. The company links Polaris to its broader plan to extract electrical energy directly from the fusion reaction using pulsed operation, suggesting that each shot in the machine provides new data on confinement, fuel handling and component stress. By highlighting deuterium-tritium operation and the specific “150 million °C” metric, Helion is signaling that it is moving into the same performance regime as large public research devices while still operating under private financing.
Helion’s Fusion Technology Explained
Helion’s core bet is a magneto-inertial fusion system that compresses plasma using strong magnetic fields in short, intense pulses rather than relying on the steady-state confinement of a tokamak. In its public materials, the company contrasts this approach with the large toroidal machines that dominate government-funded programs, arguing that pulsed magneto-inertial designs can be smaller and potentially cheaper to build. The Helion team describes Polaris as the latest in a sequence of machines intended to prove out that concept at increasing temperatures and densities, with each generation designed to run more shots and survive higher stresses than the last.
Independent coverage of Helion’s technology notes that this magneto-inertial path is innovative but unproven at commercial scale, especially when compared with more mature tokamak research programs. Analysts cited in Major financial reporting say previous Helion prototypes have demonstrated important physics milestones yet still fall short of demonstrating sustained net energy gain. According to that reporting, experts view the company’s direct electricity conversion scheme and reliance on high-repetition pulsed operation as promising ideas that will require major advances in materials, power electronics and control systems before they can underpin a grid-scale plant.
Commercialization Push
Helion’s technical claims are tightly linked to its high-profile power purchase agreement with Microsoft, which the company highlighted in a Primary Helion statement. Under that PPA, Helion is targeting delivery of at least “50 MW” of power to the grid by 2028 after a one-year ramp-up period, with Constellation named as the power marketer and transmission manager. The same statement includes backing from Microsoft president Brad Smith, who framed the agreement as part of Microsoft’s effort to secure clean energy for its operations.
Accountability-focused coverage of the PPA stresses that the contract includes penalties if Helion fails to deliver the promised power, although the exact terms have not been disclosed. That reporting also notes that Helion has previously publicized aggressive timelines for fusion milestones and that the 2028 target fits within a pattern of ambitious projections that have yet to be fully proven in hardware. According to the same analysis, the agreement gives Microsoft a potential upside if Helion succeeds while leaving the fusion company on the hook if its technology slips behind schedule.
Regulatory and Site Progress
Alongside its technical and commercial announcements, Helion has been working to secure a home for its first commercial plant, known as Orion, in Washington state. The company says Chelan County has granted a Conditional Use Permit, or CUP, for the Orion facility in Malaga, describing the approval as a key step that follows earlier environmental review under Washington’s State Environmental Policy Act. In its public statement, Helion explicitly connects this local permitting progress to its goal of supplying Microsoft with fusion power by 2028, arguing that site control and regulatory clarity are as important as physics milestones.
The state-level framework for such projects is evolving as well. An enacted Washington law addresses how fusion facilities fit within the state’s Energy Facility Site Evaluation Council, or EFSEC, process and clarifies how they are treated relative to fission plants in siting decisions. The session law’s legislative history, linked in the same Evidence trail, spells out the effective date and confirms that lawmakers intended to give fusion developers a more predictable path through permitting. That statutory clarity helps explain why Helion is moving ahead with Orion in Washington rather than shopping for a different jurisdiction.
Funding and Backers
Helion’s aggressive roadmap is underwritten by substantial private capital, with Sam Altman among its most prominent backers. Financial reporting cited in Helion coverage describes a recent fundraising round that valued the company at a multibillion-dollar level and attracted a roster of investors who are betting that fusion can become a commercial power source within the next decade. That reporting also notes that Helion has declined to share some detailed performance data even as it markets its valuation, leaving outside analysts to rely on selective disclosures about temperature, pulse rate and component testing.
The same Evidence trail highlights how Helion is channeling that funding into manufacturing scale-up, particularly around high-performance pulse capacitors and other hardware needed for rapid-fire operation. By investing in its own supply chain for these components, the company aims to avoid bottlenecks that could slow the build-out of Orion or future plants. Investors quoted in the reporting frame this manufacturing push as a sign that Helion is serious about moving beyond the lab, even if the underlying physics has not yet been demonstrated at net energy levels.
Challenges and Skepticism
Despite the excitement around 150 million degree plasma and the Microsoft deal, many experts remain skeptical that Helion can meet its 2028 grid delivery target. The accountability-oriented Accountability coverage of the Microsoft contract points out that fusion projects have historically slipped by years or decades relative to their initial timelines, and that Helion itself has previously set public goals that it did not hit on schedule. Analysts quoted in that reporting warn that compressing the remaining physics validation, engineering design, construction and regulatory approvals into the current timeframe will be extremely challenging.
Those same assessments highlight several unresolved questions, including whether Polaris or its successors can reach sustained net energy gain and whether the cost of Helion’s pulsed magneto-inertial systems can compete with other low-carbon technologies. The Evidence trail on the Use of penalties in the PPA underlines the financial risk Helion faces if it falls short, even as the company projects confidence in its ability to deliver. For now, the 150 million degree result and the Orion permits show real movement, but whether those milestones translate into reliable, affordable grid power by 2028 will depend on breakthroughs that have not yet been independently verified.
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*This article was researched with the help of AI, with human editors creating the final content.
