Durham University scientists have completed one of the largest verification programmes ever conducted on superconducting materials, a critical milestone for the ITER reactor, the world’s largest fusion energy experiment. Their extensive study not only confirmed the quality of superconducting wires essential for ITER’s giant magnets but also advanced the methods used to test them. By refining how these materials are validated, the researchers have laid the groundwork for a more reliable path to achieving practical fusion power.
Fusion energy, often described as the ‘holy grail’ of clean power, holds the promise of virtually limitless energy from abundant fuels like deuterium, zero carbon emissions, and minimal radioactive waste. Unlike fission, which splits atoms in today’s nuclear plants, fusion joins light atomic nuclei into heavier ones, releasing enormous amounts of energy—a process that powers the Sun. If harnessed on Earth, fusion could provide safe, sustainable electricity for generations.
Currently under construction in southern France, ITER (International Thermonuclear Experimental Reactor) is the largest and most ambitious fusion experiment in history. When complete, it aims to demonstrate sustained fusion at a scale never before achieved. At its heart, the ITER reactor will confine plasma—an ultra-hot, electrically charged gas—at temperatures exceeding the Sun’s core. To achieve this, the machine relies on colossal superconducting magnets capable of generating some of the strongest steady magnetic fields ever created. These magnets are only as reliable as the superconducting wires within them, making the verification of their performance an essential step toward ITER’s success.
In 2011, Durham University was selected to become one of Europe’s official reference laboratories for ITER. The team, led by Professor Damian Hampshire and Dr Mark Raine, was tasked with developing specialised methods to test the superconducting wires made from niobium-tin (Nb₃Sn) and niobium-titanium (Nb–Ti). Over more than a decade of research, the team handled 5,500 wire samples processed and tested, and performed 13,000 separate measurements. Heat treatments above 650°C were used to prepare Nb₃Sn wires before testing. The results provided unprecedented insights into both material performance and testing reliability, ensuring that each strand met the rigorous standards required for ITER’s demanding environment.
One of the most significant outcomes of the project was a statistical approach to validating Nb₃Sn wires, which are permanently altered during testing. Durham scientists demonstrated that measurements from adjacent strands across different laboratories can serve as accurate substitutes, ensuring both cost-effectiveness and consistency. This breakthrough not only boosts confidence in ITER’s magnet system but also sets a new benchmark for how superconducting materials should be tested worldwide.
Durham’s work arrives at a time when momentum for fusion energy is accelerating globally. ITER is targeting its first plasma in 2035, but private companies are pushing for commercial breakthroughs even sooner. Helion Energy has already struck a deal with Microsoft to deliver electricity from a fusion plant by 2028. Commonwealth Fusion Systems, backed by Google, has secured pre-orders for 200 megawatts of fusion power in the 2030s. The UK Government has pledged £2.5bn to fusion research and is developing its own prototype reactor, STEP, on a former coal site in Nottinghamshire. This growing international investment highlights the race to make fusion a commercial reality.
Durham’s contribution to the ITER reactor extends beyond research. The university is also a lead partner in the UK’s Centre for Doctoral Training in Fusion Power, helping to equip young scientists and engineers with the skills needed to shape the future of energy. By combining groundbreaking verification of superconducting wires with education and innovation, Durham University is not just supporting the ITER reactor—it is strengthening the global effort to turn fusion into a reliable, clean power source.
The successful completion of this vast verification programme is more than a technical achievement. It represents a step toward unlocking fusion energy’s promise: safe, abundant, and carbon-free electricity. As ITER moves closer to operation, the foundations laid by Durham University’s scientists ensure that its powerful magnets, and the future of fusion itself, rest on solid ground.