Commonwealth Fusion Systems validates SPARC tokamak’s high-field magnets

Category: Magnets, Superconductors, Tokamak

Commonwealth Fusion Systems validates SPARC tokamak’s high-field magnets
Commonwealth Fusion Systems’ high-temperature superconducting magnets pass DOE validation for SPARC tokamak, paving the way for compact fusion energy
(Image courtesy of Commonwealth Fusion Systems)

Commonwealth Fusion Systems has cleared a critical hurdle on the path to commercial fusion energy. The company’s production-grade toroidal field magnets built to confine plasma in the SPARC tokamak have passed rigorous DOE validation tests, securing an $8 million award under the Milestone-Based Fusion Development Program. These magnets will be installed in SPARC’s reactor hall in Devens, Massachusetts.

“The DOE Milestone programme is designed to promote progress in the development of commercial fusion energy through a rigorous review process of key technical milestones that will build confidence in this nascent industry,” said CFS CEO Bob Mumgaard. “Fusion will ultimately help to define the future of global energy security, economic competitiveness, and human development for generations to come. American ingenuity has helped lay the groundwork, and ongoing DOE support will help to accelerate the full realization of this groundbreaking technology.”​

Over a month of testing replicated SPARC’s operational conditions: high electrical currents, intense magnetic fields, and strong electromagnetic forces. Independent national lab reviewers scrutinized all results against strict criteria. The D-shaped coils use high-temperature superconducting REBCO tape, enabling unprecedented magnetic fields. Stronger fields allow SPARC and ARC to confine plasma more efficiently in a compact footprint, reducing complexity, costs, and accelerating commercialization.

CFS employs two magnet technologies: toroidal field magnets using NINT, housing HTS tape in steel plates, and PIT VIPER cables for pulsed magnets like the central solenoid, handling rapid current cycling with minimal degradation.

Validation confirms CFS can manufacture these complex magnets consistently. Serial production at Devens has completed over half of the 288 pancake modules for SPARC’s 18 toroidal field magnets. Early production took 30 days per pancake; now, it’s about one per day. SPARC requires about 10,000 kilometres of HTS tape, an amount unimaginable a few years ago.

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