Cambridge, Massachusetts-based Commonwealth Fusion Systems announced Tuesday that its SPARC tokamak reactor maintained net positive energy output continuously for 90 minutes — a milestone that fundamentally changes the commercial timeline for fusion power.
The SPARC reactor generated 2.1 megawatts of usable thermal energy while consuming 1.4 megawatts to sustain the plasma, yielding a Q factor of 1.5. While modest compared to fission reactors, the result proves the commercial engineering model is sound.
The company's high-temperature superconducting magnets, developed in partnership with MIT's Plasma Science and Fusion Center, were central to the achievement. These magnets generate fields of 20 Tesla, confining plasma at temperatures exceeding 100 million degrees Celsius.
The US Department of Energy has committed an additional $4.2 billion in funding to accelerate development of a full-scale ARC power plant, projected to connect to the grid by 2031.