High Energy Particles Flow Through A Tokamak Or Doughnut-Shaped Device. Antigravity, Magnetic Field,...


A private company just made a huge breakthrough in nuclear fusion

The feat marks a step toward a new source of clean energy.


As energy prices across the U.S. soar, with electricity prices jumping nine percent year-over-year, it’s become clearer by the day that affordable alternatives to fossil fuels are necessary not just for environmental reasons but also to lessen the strain on our wallets.

Nuclear fusion is one alternative on the horizon that until recent years sounded more like science fiction than fact. Now, a report from a private nuclear energy company in the U.K. has pushed this reality even closer to fruition in a donut-shaped nuclear reactor called a tokamak. Last week the company Tokamak Energy announced that its spherical ST-40 tokamak reactor reached the 100 million Celsius threshold for commercially viable nuclear fusion.

“We are proud to have achieved this breakthrough which puts us one step closer to providing the world with a new, secure and carbon-free energy source,” said Chris Kelsall, CEO of Tokamak Energy, in a statement. “[This] represent[s] the optimal route to achieving clean and low-cost commercial fusion energy.”

Here’s the background — Tokamaks aren’t the only reactors being tested for nuclear fusion — earlier this year Inverse reported on fusion breakthroughs at the Livermore Labs inertial confinement program — but they are a very popular option with a long history. In a nutshell, tokamaks are typically donut (or, torus) shaped reactors that squish and heat up hydrogen atoms in a vacuum until they transform into a plasma. With enough heat and pressure, this plasma then undergoes a fusion process similar to that at the center of a star to create a big burst of energy.

The ST-40 is not the first tokamak to reach this temperature threshold — the Princeton Large Torus tokamak reached that milestone back in 1978. But it is the first to do so with a spherical, privately-funded tokamak.

Gerald Navratil is the Edison Professor of Applied Physics at Columbia University and has been doing fusion research at the university for 45-years. Navratil is unaffiliated with the Tokamak Energy project but tells Inverse the breakthrough is exciting for the field of nuclear fusion at large.

“These are exciting times for fusion energy research,” Navratil says. “For a compact, privately funded fusion experiment at the $70 million cost range to achieve this temperature level means they’ve reached one (out of several) necessary conditions for fusion power success, which is noteworthy.”

Tokamak Energy has reached an impressive milestone.Tokamak Energy

Why it matters — In nuclear fusion research, Navratil says that privately funded projects (like ST-40) and government-funded projects (like France’s ITER) work “highly synergistically” and even symbiotically with one another. This means that breakthroughs at private companies like Tokamak Energy are good for the progress of other projects and vice versa.

“We’ve reached a level of maturity in fusion science achieved through public funding that now enables very significant (but more risky) steps in fusion energy experiments funded by private investors,” Navratil says.

“As these private ventures proceed in parallel with the public research efforts, I expect many of the private efforts may fail to fully achieve their objectives,” he continues. “The entire field will benefit from the results of these private efforts, and one or more may indeed achieve significant success.”

Success in these endeavors could revolutionize access to clean, safe, and sustainable energy sources.

What they did — We don’t know for sure the secret sauce that enabled ST-40 to reach this fusion milestone, but one unique component of the tokamak that likely played a role in its success is its spherical, rather than donut, shape. This shape means that the magnets inside the reactor are closer to the plasma stream than in torus-shaped tokamaks. As a result, smaller and cheaper magnets can be used to create even more intense fields.

Even though ST-40 was able to reach this crucial fusion threshold, Navratil says there are still many questions to answer before this kind of reaction can truly be used commercially.

“The ST-40 results claim to have achieved sufficient temperature, but for how long was this sustained? At what density? And with what ‘energy confinement time’?” Navratil says. “Commercial fusion energy [will] require advances in both physics and technology. Even after the plasma physics requirements are met, there are a host of technology requirements that must also be addressed to make fusion a commercially viable source of energy.”

This will include developing a fusion power system, power conversion technology, and next-gen radiation-resistant materials, he says.

What’s next — The list of obstacles still along the road to commercial fusion may sound daunting, but it hasn’t stopped researchers so far in their 70-year journey toward this goal. As for ST-40, Tokamak Energy is already underway designing the next generation of the reactor which they hope will inform the building of the first fusion power plant in the 2030s.

Editor’s note — This article was updated on April 4, 2022 to clarify the nature of the magnets used.

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