Thea Energy stellarator coil clears field strength test

Thea Energy’s Eos-spec planar shaping coil during testing at the company’s Kearny, NJ facility, where it generated a magnetic field above 6 T at 20 K, meeting the company’s stated performance requirements

(Image courtesy of Thea Energy)

Thea Energy has operated its first full-size, full-current, full-field planar shaping coil, a magnet milestone the company says supports its case for the core technology behind its Eos stellarator. The coil reached a magnetic field above 6 T at 20 K, meeting the company’s stated performance requirements for a power plant-relevant, steady-state fusion system. The result does not demonstrate a working fusion device, but it does validate a key hardware component at the scale required for Eos.

Planar shaping coils reach Eos field strength targets

The coil tested is representative of every shaping coil planned for Eos. Thea Energy has standardised its shaping coil array to a single circular, planar geometry, which the company says is the most efficient form factor for high-temperature superconducting tape. Because all shaping coils share one design, the manufacturing path treats each unit as a repeatable part rather than a bespoke component, a deliberate break from the complex three-dimensional magnets used in earlier stellarator programmes.

The Kearny, NJ team iterated through more than 50 generations of planar coil design in-house over the past year and a half. Thea Energy carried out the full magnet design and manufacturing at its current headquarters and says it plans to open a second facility before the end of 2026 to expand production capacity. The coils can be fully wound in tension, a property the company argues supports reproducibility at industrial volumes.

Thea Energy says Eos construction can now proceed

With field strength and current requirements met, Thea Energy says the result gives the team confidence to move into Eos manufacturing scale-up and construction. The result demonstrates design, manufacturing, and operational performance at Eos scale, according to Thea Energy. Future test campaigns will target quench survivability and digital twin modelling to continue validating robustness. System integration, plasma operation, and long-duration reliability remain ahead.

Brian Berzin, co-founder and chief executive officer of Thea Energy, said the company’s engineering philosophy centres on hardware designed for manufacturability, constructability, and long-term commercial operation. “For fusion to deliver baseload power at scale, the hardware must be streamlined and reproducible,” he said. “This latest milestone confirms that our core magnet technology meets those exact criteria.”

Eos is designed to show whether the company can build fusion systems faster and for less capital than prior approaches, claims that remain to be proven at system level. Thea Energy’s architecture replaces complex 3D coil geometries with software-controlled, planar magnet arrays. Peer-reviewed work published in IEEE Transactions on Applied Superconductivity previously confirmed that a smaller prototype array could create and control stellarator-relevant magnetic fields to within 1% of predicted values.

The company, which spun out of Princeton University and Princeton Plasma Physics Laboratory in 2022, holds six U.S. Department of Energy INFUSE awards and was selected as an inaugural awardee of the DOE’s Milestone-Based Fusion Development Program. Eos is intended to de-risk the construction and operation of Helios, Thea Energy’s planned first fusion power plant.

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