General Atomics and Tokamak Energy join forces on HTS magnet tech

June 1, 2023, 9:30AMNuclear News
GA’s Magnet Technologies Center. (Photo: GA)

General Atomics (GA) and Tokamak Energy Ltd. are each independently developing magnetic confinement fusion power plant concepts that would use a tokamak and high-temperature superconducting (HTS) magnets to confine and shape a plasma heated to over 100 million degrees Celsius. On May 30, they announced a memorandum of understanding to collaborate on HTS magnet technology for fusion energy and other applications.

Tokamak Energy’s HTS magnet technology. (Photo: Tokamak Energy)

Complementary experience: GA and Tokamak Energy are entering the deal with different—but complementary—experience and capabilities.

“GA is excited to collaborate with Tokamak Energy on HTS magnets,” said Anantha Krishnan, senior vice president at General Atomics. “Tokamak Energy is a leader in HTS magnet modeling, design, and prototyping, and GA has expertise in developing and fabricating large-scale superconducting magnets for fusion applications.”

Warrick Matthews, managing director at Tokamak Energy, said, “GA has significant experience, knowledge, and facilities to produce large superconducting magnets at scale. Tokamak Energy has been developing HTS technologies for fusion for over a decade. The integration of these complementary capabilities promises to accelerate the development and production of HTS technologies in additional fields, such as aviation, naval, space, and medical applications.”

Common confinement: The electromagnet coils in a tokamak designed by GA or Tokamak Energy would be wound from HTS tape containing a rare earth barium copper oxide (REBCO) superconducting material. By opting for superconductors, fusion power plants can use smaller coils within smaller plant footprints yet operate at greater densities than possible with conventional magnet technologies. HTS magnet operating temperatures are “high” only relative to low-temperature superconductors—Tokamak Energy plans to cool its HTS magnets to about −250°C—and they promise an operating cost advantage over low-temperature superconducting materials.

Tokamak’s tech: Tokamak Energy was founded in 2009 as a commercial fusion spin-off from the U.K. Atomic Energy Authority focusing on spherical tokamak designs. In October 2022, the company announced its ST40 spherical tokamak had reached the commercial fusion energy plasma temperature threshold of 100 million degrees Celsius. In 2024 the company plans to start operations at its Demo4 spherical tokamak magnet device. That would be followed, according to a plan announced in October 2022, by operation in 2026 of a high field spherical tokamak using HTS magnets, dubbed the ST80-HTS, which in turn would be followed by a fusion pilot plant called ST-E1 that the company says could deliver electricity into the grid in the early 2030s and produce up to 200 MWe.

Earlier this year, Tokamak Energy announced it was sending HTS magnets to the Department of Energy’s Sandia Laboratories for gamma radiation testing.

GA’s tech: GA began working on superconducting magnet technologies in the 1980s, and in 2015 established its Magnet Technologies Center to fabricate the central solenoid modules for the international ITER experiment. The company is also developing other technologies for ITER, including high-power microwave transmission line components, real-time plasma control software, and specialty diagnostic systems.

GA announced in October 2022 that it had developed a compact tokamak fusion pilot plant concept that would use HTS magnets and silicon carbide in the walls of the liquid metal breeding blanket that surrounds the plasma to carry heat away and breed tritium fuel. GA has over five decades of experience operating tokamaks, including the DIII tokamak, a Department of Energy facility which achieved its first plasma in early 1978 and is now operated by GA as the DIII-D National Fusion Facility.

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