For half a century, fusion was always 30 years away. A compact machine being assembled in Devens, Massachusetts, is changing that story. Here is what fusion is, why it has been so hard, and why it matters to anyone watching AI data centers.
By Ken Tapp, a director of Complete Defense Solutions
About 35 miles west of Boston, in a quiet industrial park in Devens, Massachusetts, sits a building most people drive right past. Inside, a team is assembling a machine that, for decades, many experts said could not be built this small. It is designed to hold a fire hotter than the center of the sun, just a few feet from magnets kept colder than deep space.
If it works, it could change how America thinks about power, including the power behind artificial intelligence and national defense.
The Old Joke
For about half a century, physics students shared the same joke: fusion is 30 years away, and it always will be.
The joke stuck because fusion may be the best energy source ever found. It is what powers the sun. Today's nuclear plants use fission, which splits heavy atoms like uranium, produces long-lived waste, and needs constant cooling. Fusion works the other way. It presses the lightest atoms, forms of hydrogen, together until they fuse into helium. The machine holds only a tiny amount of fuel at a time, and if something goes wrong, the reaction simply goes out.
Why It Has Been So Hard
The problem is heat. Fusion on Earth needs plasma at roughly 100 million degrees Celsius. No material container can touch it, so scientists use a magnetic cage shaped like a hollow doughnut, called a tokamak.
The catch has always been magnet strength. Weak magnets leak heat, so machines had to be enormous. That thinking produced ITER, a massive international project in southern France backed by 35 nations. It has taught the field a great deal, but its cost has grown into the tens of billions of dollars, and full operations are now planned for the mid-2030s.
The Magnet That Changed the Math
Researchers at MIT asked a simple question: why does it have to be that big? Their answer was the magnet. In a tokamak, doubling the magnetic field can raise fusion power from the same size chamber by about 16 times.
The breakthrough material was high-temperature superconducting tape, about as wide as a strip of fettuccine. In 2018 the team spun out Commonwealth Fusion Systems (CFS). In September 2021, a large magnet built from that tape reached 20 tesla, compared with about 3 tesla in a strong hospital MRI. The company says magnets like this are strong enough to lift an aircraft carrier out of the water.
Where Things Stand Today
CFS's demonstration machine, SPARC, is being assembled in Devens. In January 2026 the company installed the first of SPARC's 18 superconducting magnets, and it is now aiming for first plasma in 2027. The next goal is net energy: getting more energy out of the fusion reaction than it takes to heat the plasma.
That milestone has not been reached. Fusion dates have slipped before and could slip again. But this is real hardware, not a drawing on a whiteboard.
The Plant Meant for the Grid
SPARC is a proof of concept. The commercial plant, ARC, is planned for Chesterfield County, Virginia, just outside Richmond, aiming for the early 2030s at around 400 megawatts.
Virginia is the heart of America's data center industry, and the early customers are telling. Google has signed a power purchase agreement for ARC's output, and the energy company Eni has signed a deal worth about $1 billion. Because the back half of a fusion plant is a conventional steam turbine, a future fusion core could one day sit on the site of a retiring coal or gas plant and reuse its existing transmission lines.
Washington is paying attention too. The Department of Energy's Fusion Science and Technology Roadmap lays out a national strategy to accelerate fusion commercialization by the mid-2030s, and the Department of War and Department of Energy have partnered on nuclear energy initiatives to strengthen national security.
Why This Matters to AI Arsenals and Complete Defense Solutions
National security now runs on computing power. Defense companies and the military rely more and more on AI for design, logistics, manufacturing, and decision-making. If that computing depends on a strained public grid, one outage can take it offline.
That is why we believe defense AI compute should be secured and powered by its own sovereign, behind-the-meter energy, so that if the grid goes down, the data center does not. The key word is resilience.
Today, AI Arsenals is exploring practical options for sovereign power, from natural gas turbines to micro reactors to solar thermal. To stay ahead of the curve, the team is also watching the fusion field closely and learning from the companies working in it. Fusion is not ready to power a data center yet. When it is, we intend to understand it better than anyone.
Looking Ahead
The next time someone says fusion is always 30 years away, think of that quiet building in Devens. A small team looked at a problem the size of a stadium and fit the answer into a much smaller machine. Whether SPARC hits its goals on schedule or not, the old rule that fusion has to be enormous is already starting to crumble.
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Sources
- US fusion company installs first of 18 SPARC magnets; first plasma in 2027 — Fortune, January 7, 2026
- CFS working with NVIDIA, Siemens on SPARC digital twin — American Nuclear Society, January 8, 2026
- MIT spinout Commonwealth Fusion Systems unveils plans for the world's first fusion power plant — MIT News
- CFS SPARC net energy gain plans — OneStop ESG, November 2026
- Fusion Energy — U.S. Department of Energy
- Department of War Partners With Department of Energy in Historic Nuclear Energy Initiative — U.S. Department of War
Forward-looking statements: This article contains forward-looking statements regarding the development and timing of fusion energy technologies and power plants being built by third parties, government energy initiatives, and AI Arsenals' exploration of sovereign power and secured AI compute solutions, including its monitoring of the fusion field. AI Arsenals has not invested in any fusion company. These statements involve risks and uncertainties, and actual results may differ materially. No investment, project, or financing is assured.
Important Information:
This article is published for general informational purposes only. It is not an offer to sell or a solicitation of an offer to buy any securities of CFSU, Complete Defense Solutions, Inc. ("CDS"), Ai Arsenals, Inc. ("Ai Arsenals") or any other company, and nothing in it is investment, legal, accounting or tax advice.