UK-based Tokamak Energy has recorded a significant breakthrough in the development of clean energy by successfully replicating fusion power plant fields within its Demo4 magnet system. This is the first time in the world that such fields have been created in a full High Temperature Superconducting (HTS) magnet configuration. During recent tests conducted at the company’s headquarters near Oxford, the Demo4 system achieved magnetic field strengths of 11.8 Tesla at a temperature of -243 degrees Celsius (-405.4 degrees Fahrenheit).
The system, which features a complete set of HTS magnets built in a tokamak configuration, successfully managed seven million ampere-turns of electrical current through its central column. Warrick Matthews, CEO of Tokamak Energy, described the results as a major victory for the sector. “Demo4 represents over a decade of HTS innovation at Tokamak Energy. Born from our fusion mission, it validates one of the technical solutions for getting clean, limitless, safe and secure fusion energy on the grid,” Matthews said.
Validating system-level performance Creating fusion energy requires extremely strong magnetic fields to confine and control hydrogen fuel, which is heated to a plasma state several times hotter than the sun’s core. While single high-field HTS magnets have been demonstrated previously, Demo4 addresses the next critical engineering challenge: validating a complete magnet system.
In a functioning fusion power plant, superconducting tapes must operate within a complex magnetic environment created by neighboring coils. These conditions significantly influence structural performance and critical current. Demo4 allows engineers to generate and study these fusion-relevant forces across a system coil set, which includes 14 toroidal field magnets and two poloidal field magnets.
Graham Dunbar, Demo4 chief engineer, noted that the platform is providing unique engineering data to inform future power plant designs. “This isn’t just about achieving a number; it’s about gaining the confidence and build expertise to scale our technology for future energy-producing fusion systems,” Dunbar stated.
Commercial applications beyond fusion The tests also highlighted the commercial potential of HTS technology for sectors outside of fusion energy. HTS materials can deliver approximately 200 times the current density of copper, making them viable for power distribution in data centers, electric motors for zero-emission flight, and magnetic levitation transport systems.
According to the company, these magnets can be made smaller and lighter than traditional low-temperature superconductors and operate at a fraction of the cooling cost. Tokamak Energy indicated that further testing to reach higher magnetic fields is ongoing, with the next set of results expected in early 2026. High-speed plasma imagery In a related development, the firm earlier released the first high-speed color images of plasma captured inside a fusion energy machine, offering new visual insights into the behavior of the fuel.
This research supports the advancement of X-point radiator (XPR) regimes, a promising operating mode for future fusion power plants. XPR regimes are designed to cool the plasma’s edge before it contacts reactor components, reducing wear on the hardware without compromising performance.
The ability to visualize how lithium interacts with the plasma in real-time serves as a significant step toward validating this enabling technology.
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