We've Long Waited for Fusion. This Reactor May Finally Deliver It—Fast.

From Popular Mechanics

  • An MIT- and startup-designed fusion reactor could be testing in four years and online within 10.

  • The scientists say this ambitious timeline is a result of careful, transparent planning—not handwaving.

  • The industry is skeptical, but Sparc's gameplan seems to echo some fission reactor trends, too.


Researchers at the Massachusetts Institute of Technology (MIT) are collaborating on a new “compact” fusion reactor that could feasibly be built and go online much faster than existing fusion reactor concepts. Does that mean fusion’s Lucy will finally let an industry Charlie Brown kick the football? Maybe.

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The New York Times reports:

“Construction of a reactor, called Sparc, which is being developed by researchers at the Massachusetts Institute of Technology and a spinoff company, Commonwealth Fusion Systems, is expected to begin next spring and take three or four years, the researchers and company officials said.”

Granted, that’s just construction. Next comes phases of testing and then, if the reactor reaches productive fusion, a long process of designing and building a power plant. But within fusion research, a timeline that claims commercial fusion power within a decade immediately jumps to the very front of the line—so much so that it naturally causes skepticism.

How is this reactor promising such a short development time compared with its peers? It sounds like the Sparc scientists learned some lessons from groups developing the current generation of small fission reactors as well as those with their eyes on next-generation fission. The two key takeaways: improving materials and shrinking costs.


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A traditional tokamak like ITER uses a gigantic magnetic field to contain the extraordinarily hot plasma. Sparc, meanwhile, uses a “a newer electromagnet technology that uses so-called high temperature superconductors that can produce a much higher magnetic field,” the Times reports.

That means a smaller amount of plasma, a smaller entire reactor form factor, and perhaps fewer problems with containing and sustaining plasma, which have thwarted existing plasma fusion projects.

Research programs and government projects around the world have studied tokamak, stellarator, and other fusion reactor design for decades with relatively few milestones reached. The record for sustained fusion time is just a fraction of a second, and one industry joke goes that fusion is always 30 years away.

The fraction of a second on record was also totally subsumed by the massive amount of energy the host reactor used to get up to temperature and stay contained and externally cooled.

Everyone involved with fusion is working hard with extremely complex science, and the delays aren’t because anyone is foolish. Fusion involves heating contained matter to at least or even many times more than the temperature of the sun, and then keeping that reaction at temperature with necessarily fussy containment. The promise of almost limitless power for almost limitless time is what keeps people searching.

But there are also major and inherent downsides. Sparc promises to return 10 times the energy it uses as power output, which is very, very far from the “limitless energy” concept suggested by the sun. But bringing a miniature sun to Earth means, in a way, adding “extremophile” technology demands.

Sparc has made headlines for being very transparent about what, when, and how the team behind the reactor is doing things. While that creates higher expectations, it also has the potential to build more interest and trust.

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