US energy company installs first magnet for Sparc fusion reactor

Commonwealth Fusion Systems (CFS) announced a significant milestone at CES 2026 with the installation of the first of 18 powerful D-shaped magnets for its Sparc fusion reactor, a demonstration device aimed for activation next year. Each magnet weighs about 24 tons and generates a 20-tesla magnetic field, roughly 13 times stronger than a standard MRI machine. These magnets will form a doughnut-shaped structure to confine plasma heated to over 180 million degrees Fahrenheit, cooled to -423°F to safely conduct over 30,000 amps of current. The reactor’s cryostat, a 24-foot-wide stainless steel circle weighing 75 tons, was installed in March, and the magnets will be assembled throughout the first half of 2026. To optimize reactor performance, CFS is collaborating with Nvidia and Siemens to develop a digital twin of Sparc, integrating real-time simulations with the physical reactor. This digital twin will enable virtual testing and parameter adjustments, reducing trial-and-error in