The encouraging part arrived on a Las Vegas stage: at CES 2026 in January, Commonwealth Fusion Systems said it had installed the first of 18 magnets in Sparc, the demonstration reactor it hopes to fire up next year. For a company racing rivals to send the first fusion electrons to the grid in the early 2030s, the hardware is finally going into the machine.
The numbers behind the magnets explain the pace. Each D-shaped unit runs about 24 tons and produces a 20 tesla magnetic field, roughly 13 times a typical MRI machine; Mumgaard put it memorably: “It’s the type of magnet that you could use to, like, lift an aircraft carrier”. Mounted upright on a stainless steel circle 24 feet across and weighing 75 tons, a base known as a cryostat that was set in place the previous March, they will be chilled to -253 degrees C, -423 degrees F, to safely carry over 30,000 amps, while the plasma inside burns hotter than 100 million degrees Celsius. CEO Bob Mumgaard says key components are complete and all 18 should be in by the end of summer: “It’ll go bang, bang, bang throughout the first half of this year as we put together this revolutionary technology”.
The second announcement is quieter but may matter as much. CFS is pairing with Nvidia and Siemens on a digital twin of Sparc, feeding Siemens design and manufacturing data into Nvidia’s Omniverse libraries, so that, in the CEO’s words, “these are no longer isolated simulations that are just used for design. They’ll be alongside the physical thing the whole way through, and we’ll be constantly comparing them to each other.” The payoff: “It will run alongside so we can learn from the machine even faster”.
The bill underlines how real this has become. CFS has pulled in nearly $3 billion so far; August brought an $863 million Series B2 round with Nvidia, Google and nearly three dozen backers. Next comes Arc, the follow-on commercial-scale plant, first of its kind, with another several billion dollars on top, by CFS’s own estimate. On its home page the company, working with MIT on high-temperature superconducting magnets to shrink the tokamak, calls Sparc the first commercially relevant net-energy fusion machine and the gateway to Arc as a power plant.
Cautious hope remains the right posture: the reactor is not finished, the gain not banked, the grid date still a promise. But the direction is compounding. “As the machine learning tools get better, as the representations get more precise, we can see it go even faster, which is good because we have an urgency for fusion to get to the grid”, Mumgaard said. Step by step, magnet by magnet, the timeline is shortening.
Sources
- Commonwealth Fusion Systems installs reactor magnet, lands deal with Nvidia | TechCrunch
- Home | Commonwealth Fusion Systems
