CFS ships first HTS magnet for SPARC tokamak, unlocking compact fusion power

CFS’s first 24-ton HTS toroidal field magnet, now installed at SPARC, showcases the compact power driving fusion’s commercial breakthrough.

(Image courtesy of Commnwealth Fusion Systems)

Commonwealth Fusion Systems has shipped the first full-scale toroidal field magnet destined for its SPARC tokamak, marking a tangible step forward for high-temperature superconducting technology in commercial fusion development.

The 24-ton, D-shaped magnet left CFS’s factory in early January and is now installed at the SPARC site in Devens, Massachusetts. Generating fields above 20 teslas, it uses a non-insulated, non-twisted pancake winding of rare-earth barium copper oxide tape, a design that traces its lineage directly to the company’s landmark 2021 prototype but now built to production tolerances. Where conventional low-temperature superconducting coils demand deep cryogenic infrastructure and sprawling footprints, the REBCO-based design operates at comparatively higher temperatures while delivering greater field strength in a significantly smaller envelope.

Seventeen more magnets are being produced at the same facility to complete SPARC’s full toroidal array. The factory cadence matters as much as the first delivery. It demonstrates that what began as a research breakthrough can be manufactured at pace, which has been a persistent question mark hanging over the high-field tokamak approach since CFS first published its magnet performance data.

SPARC is targeting first plasma around 2025, with net energy gain demonstrations to follow. If plasma tests validate the magnet array at scale, the program would become the most compelling proof point yet that compact, high-field tokamaks can close the physics gap that has kept fusion perpetually out of reach. CFS’s follow-on ARC reactor is designed to feed electricity to the grid, and how SPARC performs will determine how seriously that timeline is taken.

Stay ahead in the fusion revolution explore more breakthroughs from leading innovators in clean energy technology.