Tokamak Energy’s Demo4 Magnet Shatters Barriers on the Road to Fusion Power
- Ritambhara K
- 3 days ago
- 2 min read
Tokamak Energy has achieved a major breakthrough on the journey toward clean, virtually limitless fusion power. For the first time, the company has successfully recreated the extreme magnetic fields required inside a future fusion power plant using its world-leading high-temperature superconducting (HTS) magnet system.
The Demo4 platform not only marks a milestone for fusion research, but also highlights the revolutionary potential of HTS technology across multiple industries—from power distribution in energy-hungry data centers to electric propulsion for zero-emission aircraft, and advanced magnetic levitation transport systems.
Fusion energy demands extraordinarily powerful magnetic fields to confine and control hydrogen fuel, which is heated into plasma at temperatures several times hotter than the center of the sun. This plasma is contained within a doughnut-shaped chamber called a tokamak.
At Tokamak Energy’s Oxford-area headquarters, the Demo4 system—an integrated set of HTS magnets arranged in a full tokamak configuration—delivered remarkable results. Recent tests achieved magnetic fields of 11.8 Tesla at –243°C, setting a new global standard.
Even more impressive, the system generated seven million ampere-turns of electrical current through its central column. HTS materials can carry up to 200 times more current density than copper, demonstrating extraordinary promise for future high-efficiency power systems.
“This is a landmark moment in the race to deliver fusion energy and advance HTS as a disruptive commercial technology,” said Warrick Matthews, CEO of Tokamak Energy. “Demo4 crowns more than a decade of innovation. It validates a key technical pathway for bringing clean, safe, and secure fusion energy to the grid—while also showcasing the wider potential of superconductors across science, propulsion, and power infrastructure.”
Inside Demo4, enormous magnetic forces are generated by driving high electrical currents through precision-engineered electromagnetic coils. These coils are wound from advanced HTS tapes—multilayered metal conductors containing a vital internal layer of REBCO (rare-earth barium copper oxide), one of the world’s most advanced superconducting materials.
Rather than focusing on individual magnet performance alone, Tokamak Energy set its sights higher: validating a complete, fully integrated HTS magnet system. In a real fusion power plant, each REBCO tape must endure complex, overlapping magnetic forces from neighboring coils—conditions impossible to replicate with isolated magnet tests.
Demo4 is therefore the world’s first platform capable of generating and studying fusion-relevant magnetic interactions across a full system of 14 toroidal field coils and two poloidal field coils. The resulting data offers unparalleled insight for designing next-generation fusion power plants.
“Demo4 is doing exactly what we engineered it to do,” said Graham Dunbar, Demo4 Chief Engineer. “Each test yields invaluable data that strengthens our understanding and our confidence. This isn’t just about hitting numbers—it’s about building the expertise to scale this technology into future fusion power systems.”
The results confirm that Tokamak Energy’s HTS magnets can produce the extreme fields needed for fusion while supporting far higher current densities with efficient plug-in cooling. As a result, these magnets can be built smaller, lighter, and operated at far lower cost than conventional low-temperature superconductors. Further testing is underway, with even higher field results expected in early 2026.