Fusion energy startup Helion announced Friday that it has reached an important milestone in its quest for fusion energy. The plasma inside the company’s prototype reactor, Polaris, reaches 150 million degrees Celsius, three-quarters of the temperature the company believes is needed to operate a commercial fusion power plant.
David Kirtley, co-founder and CEO of Helion, told TechCrunch:
Polaris also operates on deuterium-tritium fuel (a mixture of the two hydrogen isotopes), which Kirtley said would make Helion the first fusion company to do so. “As expected, we saw a dramatic increase in fusion power output in the form of heat,” he said.
The Everett, Washington-based startup is in competition with several other companies seeking to commercialize fusion power, a potentially limitless source of clean energy.
That potential has investors betting on this 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 in the process of raising $250 million, while last summer Commonwealth Fusion Systems raised $863 million from investors including Google and Nvidia. Helion itself raised $425 million last year from a group that includes Sam Altman, Mithril, Lightspeed, and SoftBank.
While most other fusion startups aim to put power on the grid in the early 2030s, Helion has a deal with Microsoft to sell power starting in 2028, but that power will come not from Polaris but from a large commercial reactor called Orion that the company is currently building.
Every fusion startup has its own milestones based on the reactor design. For example, Commonwealth Fusion Systems needs to heat plasma to more than 100 million degrees in a tokamak, a doughnut-shaped device that uses powerful magnets to confine the plasma.
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Helion’s reactor is different, requiring a plasma about twice as hot to function as intended.
The company’s reactor design is a so-called field-reverse configuration. The inner chamber looks like an hourglass, with fuel being injected into plasma at the wide end. Magnets then accelerate the plasma toward each other. When they first combine, their temperature is about 10 million to 20 million degrees. A powerful magnet then further compresses the bound balls, raising their temperature to 15000 degrees. Everything happens within 1 millisecond.
Instead of extracting energy in the form of heat from a fusion reaction, Helion uses the magnetic field of the fusion reaction itself to generate electricity. Each pulse pushes back against the reactor’s own magnets, inducing a current that can be collected. The company hopes to be more efficient than its competitors by harvesting power directly from fusion reactions.
Last year, Helion improved some of the circuitry inside its reactors to increase the amount of electricity it recovers, Kirtley said.
The company currently uses deuterium-tritium fuel, but plans to use deuterium-helium-3 in the future. Most fusion companies plan to use deuterium and tritium to extract energy as heat. Helion’s fuel of choice, deuterium helium-3, produces more charged particles and pushes out the magnetic fields that confine the plasma, making it more suitable for Helion’s approach of directly producing electricity.
Helion’s ultimate goal is to generate plasma that reaches temperatures of 200 million degrees Celsius, far exceeding the goals of other companies, depending on the company’s reactor design and fuel selection. “We believe we are in the optimal sweet spot where we want to operate power plants at 200 million degrees,” Kirtley said.
When asked whether Helion had reached a scientific break-even point (the point where it produces more energy than is needed to start a fusion reaction), Kirtley quipped. “We’re focusing on the electrical part of making electricity, rather than pure science milestones.”
Helium-3 is common on the Moon, but not on Earth, so Helion will have to manufacture its own fuel. First, deuterium nuclei are fused together to produce the first batch. In normal operation, the primary power source is deuterium-helium-3 fusion, but some reactions are still deuterium-deuterium bonds, which produce helium-3, which the company refines and reuses.
Work has already begun to improve the fuel cycle. “We were pleasantly surprised in that a lot of the technology was probably easier to implement than we expected,” Kirtley said. Helion was able to produce helium-3 “with very high efficiency in terms of both throughput and purity,” he added.
Helion is currently the only fusion startup using helium-3 as fuel, but Kirtley said he thinks other companies will do so in the future, suggesting he would be open to selling helium-3. “Others will want to use helium-3 fuel as well, as they realize they want to implement this approach of direct electricity recovery and see the efficiency gains that come with it,” he said.
Alongside its experiments at Polaris, Helion is also building Orion, a 50-megawatt fusion reactor needed to fulfill its contract with Microsoft. “Our ultimate goal is not to build and deliver Polaris,” Kirtley said. “This is a step toward large-scale power plants.”
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