Commonwealth Fusion Systems installs reactor magnets, Commonwealth meets Nvidia

Commonwealth Fusion Systems (CFS) said on Tuesday at The cost of CES 2026 that it installed the first magnet in the Sparc fusion reactor, a demonstration device they hope to fire up next year.

The magnet is the first of the 18 that, when the reactor is finished, will form a donut like shape that will release the magnetic force to block and compress the superheated plasma. If all goes well, the plasma will release more energy than it does to heat and pressurize it.

After decades of promises and delays, the power of integration appears to be at hand – CFS is a competitor are locked in a race to supply the first electrons to the group sometime in the early 2030s. If it’s done, the power combination can unlock unlimited power in a package that matches traditional power supplies.

The main components of Sparc’s magnets have been completed, and the company expects to install all 18 by the end of the summer, said Bob Mumgaard, CFS co-founder and CEO. “It will be going, bang, bang in the first half of this year as we integrate this revolutionary technology.”

Once installed, the D-shaped magnets sit upright on a 24-ton, 75-ton stainless steel cryostat, was launched last March. The magnets weigh about 24 tons each and can produce a magnetic field strength of 20 tesla, about 13 times that of a conventional MRI machine. “It’s the kind of magnet that you would use, like lifting an aircraft carrier,” Mumgaard said.

To hold that power, the magnets must be hardened to -253˚ C (-423˚F) to handle 30,000 amps of current. Inside the donut, the plasma will be burning at more than 100 million degrees.

To iron out as many kinks as possible before Sparc opens, CFS said Tuesday it is working with Nvidia and Siemens to develop digital twins for the rector. Siemens is offering design and manufacturing software, which will help the company collect data to feed into Nvidia’s Omniverse library.

It will not be CFS’ first simulation – the company is already running many simulations to predict the performance of different parts of the reactor – but the effort is there to provide results separately, Mumgaard said. With digital twins, he said, “these are no longer individual simulations that are used only for automation. They will be with the physical objects all the time, and we will always compare them.”

The hope is that CFS can run tests or change parameters in the digital twin before using them at Sparc itself. “It’s going to work together so we can learn from the machine faster,” he said.

Building Sparc has been expensive. CFS has raised nearly $3 billion to date, including $863 million Series B2 round in August that included investments from Nvidia, Google, and about a dozen others. The company’s first electric plant, Arc, will be the first of its kind. As a result, it will likely cost several billion dollars, CFS estimates.

Mumgaard hopes that the digital twin and AI technology will help the company provide integrated power to the group in the near future. “As machine learning tools get better, as the displays get better, we can see them moving faster, which is good because we have an urgent need to integrate to get to the grid,” he said.

Follow along with all of TechCrunch Coverage of the annual CES conference here.