China’s fusion energy programme has crossed a significant engineering threshold. Two fully domestically developed superconducting magnets — the core components of a fusion reactor — have passed expert acceptance and full-parameter testing at the Institute of Plasma Physics, Chinese Academy of Sciences (ASIPP) in Hefei, Anhui Province, marking what officials describe as a major step in translating controlled nuclear fusion from laboratory demonstration into a viable energy source.
A record-breaking toroidal field magnet
The toroidal field (TF) superconducting magnet, the largest of its kind ever built for a fusion device, measures 21 metres in length, 12 metres in width and 3.3 metres in height, and weighs 582 tonnes. A toroidal field magnet performs the least glamorous but most consequential function in a tokamak: its magnetic field suspends plasma running hotter than 100 million degrees Celsius — roughly seven times the temperature at the Sun’s own core — in mid-air, since no material could survive direct contact with fuel that hot.
Against the equivalent component built for the International Thermonuclear Experimental Reactor (ITER) in France — the flagship multinational fusion project — the Chinese magnet is 1.3 times the volume and stores three times more energy. Field strength is rated at 6.5 tesla, against a targeted service life of sixty years — for scale, a typical hospital MRI machine operates between 1.5 and 3 tesla, and this single coil is not yet the finished product. Sixteen such magnets are intended to eventually be assembled into the complete toroidal field system of a future reactor.
Alongside the TF magnet, a high-temperature superconducting central solenoid coil also completed full-load testing, operating at a stable current of 60 kiloamperes with energy storage of 6.03 megajoules, with performance indicators described as world-leading. This coil functions as the reactor’s “power heart,” inducing and driving the plasma current that directly determines whether a fusion reactor can ignite and sustain a stable burn.
Engineering under extreme constraints
Test data showed the coil carrying a stable current with key indicators — stored energy, maximum field ramp rate, and joint resistance — all reaching internationally leading levels. Song Yuntao, director of ASIPP, framed the achievement’s significance in terms of supply-chain independence rather than raw engineering scale alone. Song noted that the coil carries the highest energy storage capacity among all superconducting coils currently in existence, and that the special stainless steel, insulating materials and superconducting materials involved were all domestically produced — the project realised, in his words, with entirely domestic content.
Song elaborated that the breakthrough’s core value lies in full-chain self-reliance — from raw materials such as superconducting tapes, high-strength cryogenic stainless steel and specialised insulation, through the complete manufacturing sequence of structural design, precision winding, ultra-low-resistance joint fabrication and quench protection — asserting that China has broken foreign technological monopolies across that chain. The project reportedly required six years of dedicated design, research and testing, yielding forty-seven authorised patents and fourteen established technical standards.
Where this fits in China’s fusion roadmap
The magnet system supports Beijing’s ambition to generate electricity from fusion power by approximately 2030, as part of a broader, staged national programme. The milestone builds on prior progress from the Experimental Advanced Superconducting Tokamak (EAST) — popularly known as China’s “artificial sun,” which sits alongside CRAFT as part of the country’s long-term fusion commercialisation effort — and which set a widely reported endurance record earlier this year for sustained high-temperature plasma confinement.
None of this amounts to a working fusion reactor, and industry observers — inside and outside China — continue to stress that the harder problems remain ahead: full reactor assembly integrating all sixteen magnet segments, years of long-duration operational testing under reactor-representative conditions, and, ultimately, the unresolved central challenge of fusion engineering worldwide — demonstrating net energy gain, where the reactor produces more power than it consumes to sustain the reaction. A magnet, however record-breaking, is one subsystem among many that must work in concert.
The magnet’s significance for the global fusion race is less about the tonnage than about the supply chain claim: if China’s account of full domestic sourcing holds up under independent scrutiny, it signals that at least one major fusion programme is no longer dependent on the small number of Western and Japanese superconductor suppliers that currently constrain ITER-scale projects everywhere, including ITER itself. That is arguably the more consequential story than the size record.
–Kuppuswamy S
