Everett, Washington-based fusion energy startup Helion announced Friday that it has achieved a significant milestone in its exploration of fusion power. The plasma inside the company’s Polaris prototype reactor has reached 150 million degrees Celsius, three-quarters of what the company thinks it would need to operate a commercial fusion power plant.
“We’re obviously really excited to get into this space,” Helion co-founder and CEO David Kirtley told TechCrunch.
Polaris is also working on using deuterium-tritium fuel – a mixture of two hydrogen isotopes – which Kirtley said makes Helion the first fusion company to do so. “We were able to see the fusion power output increase dramatically as expected as we warmed up,” he said.
The startup is in competition with several other companies looking to commercialize fusion power, a potentially unlimited source of clean energy.
That potential has investors rushing to bet on the technology. This week, Inertia Enterprises announced a $450 million Series A round that included Bessemer and GV. In January, Type One Energy told TechCrunch it was looking to raise $250 million, while last summer Commonwealth Fusion Systems raised $863 million from investors including Google and Nvidia. Helion raised $425 million last year from the likes of Sam Altman, Mithril, Lightspeed and SoftBank.
While most other fusion startups are aiming for the early 2030s to put power on the grid, Helion has a contract with Microsoft to sell power starting in 2028, though that power will come from a large commercial reactor called Orion that the company is currently building, not from Polaris.
Each fusion startup has its own milestones based on the design of its reactor. For example, Commonwealth Fusion Systems needs to heat its plasma to more than 100 million degrees Celsius inside its tokamak, a donut-shaped device that uses powerful magnets to contain the plasma.
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Helion’s reactor is different, requiring nearly twice as much hot plasma to function as intended.
The company’s reactor design is called a field-reverse configuration. The chamber inside resembles an hourglass, and at the wide ends, fuel is injected and turns into plasma. The magnets then accelerate the plasma toward each other. When they first merge, their temperatures are about 10 million to 20 million degrees Celsius. Powerful magnets then compress the merged ball further, raising the temperature to 150 million degrees Celsius. All this happens in less than a millisecond.
Instead of extracting energy from fusion reactions as heat, Helion uses the fusion reaction’s own magnetic field to generate electricity. Each pulse will push back the reactor’s own magnets, producing an electrical current that can be collected. By producing electricity directly from fusion reactions, the company hopes to be more efficient than its competitors.
Over the past year, Kirtley said Helion had refined some of the circuits in the reactor to increase how much electricity they could recover.
While the company uses deuterium-tritium fuel today, it plans to use deuterium-helium-3 in the future. Most fusion companies plan to use deuterium-tritium and extract the energy as heat. Helion’s fuel alternative, deuterium-helium-3, produces more charged particles, which push forcefully against the magnetic fields confining the plasma, making it better suited to Helion’s approach of generating electricity directly.
Helion’s ultimate goal is to produce plasma with temperatures up to 200 million degrees Celsius, far exceeding the goals of other companies, which is a function of its reactor design and choice of fuel. “We believe that at 200 million degrees, you reach the optimal sweet spot where you want to operate the power plant,” Kirtley said.
When asked whether Helion scientists had reached breakeven – the point where a fusion reaction produces more energy than is needed to start it – Kirtley demurred. “We focus on making electric pieces, electricity, rather than pure scientific milestones.”
Helium-3 is common on the Moon, but not here on Earth, so Helion must make its own fuel. To begin with, it will fuse deuterium nuclei to produce the first batch. In regular operation, while the main source of power will be deuterium-helium-3 fusion, some reactions will still be deuterium-on-deuterium, producing helium-3 that the company will purify and reuse.
Work is already underway to refine the fuel cycle. “It’s been a pleasant surprise that a lot of that technology has turned out to be easier to do than we expected,” Kirtley said. Helion “is capable of producing helium-3 at very high efficiency, both in terms of throughput and purity,” he said.
While Helion is currently the only fusion startup using helium-3 in its fuel, Kirtley said he thinks other companies will do so in the future, indicating he would be willing to sell it to them. “Other people – as they come along and recognize that they want to take this approach of direct power recovery and see efficiency gains from it – they will also want to use helium-3 fuel,” he said.
Along with its experiments with Polaris, Helion is also building Orion, a 50-MW fusion reactor that it needs to fulfill its Microsoft contract. “Our ultimate goal is not to build and deliver Polaris,” Kirtley said. “This is a step toward large-scale power plants.”
