In a monumental leap forward for fusion energy, the ITER reactor project has completed all major components for its colossal superconducting magnet system.
This achievement marks a turning point for the world’s largest and most advanced fusion experiment, designed to prove that replicating the Sun’s energy is not only possible but scalable and sustainable.
At the core of this breakthrough is the final module of the Central Solenoid – ITER’s most powerful magnet – now ready for assembly at the project’s site in Southern France.
Weighing in at thousands of tons and reaching magnetic forces powerful enough to lift an aircraft carrier, this system will drive the fusion process that lies at the heart of ITER’s mission: producing clean, safe, and virtually limitless energy.
ITER explained
The ITER reactor, short for International Thermonuclear Experimental Reactor, is a global scientific partnership involving over 30 countries.
Its aim is to harness nuclear fusion – the same energy process that powers stars – to create a viable, carbon-free energy source for Earth.
When fully operational, ITER will be the first fusion device to produce more energy than it consumes, achieving a net energy gain.
The reactor’s primary structure is a Tokamak, a doughnut-shaped chamber where hydrogen isotopes are superheated and fused together.
Unlike fission, which splits atoms, fusion combines them, releasing enormous amounts of energy without producing long-lived radioactive waste or greenhouse gases.
How the magnet system enables fusion
At the centre of ITER’s Tokamak lies a sophisticated pulsed superconducting magnet system that manipulates plasma – the superheated, electrically charged gas necessary for fusion:
- Fuel injection: Deuterium and tritium, two hydrogen isotopes, are introduced into the chamber.
- Ionisation: The magnet system triggers a current that turns the gas into plasma.
- Magnetic containment: Superconducting magnets shape and confine the plasma in a stable position.
- Extreme heating: Auxiliary systems raise the plasma temperature to 150 million degrees Celsius – ten times hotter than the Sun’s core.
- Fusion ignition: Under these conditions, atomic nuclei fuse and release vast quantities of heat energy.
This sequence is designed to produce a tenfold energy return –500 megawatts of output from just 50 megawatts of input – turning the system into a self-sustaining “burning plasma.”
The role of the Central Solenoid
The Central Solenoid, recently completed in the United States, is the most powerful of ITER’s magnets.
Comprising six massive modules, it is designed to deliver the pulsed electrical currents that initiate and maintain the plasma current within the Tokamak.
Its advanced exoskeleton consisting of over 9,000 components, will support the intense mechanical forces generated during operation.
This magnet works in concert with six Poloidal Field magnets, built by Russia, Europe, and China, to control the plasma’s vertical stability and shape.
A global collaboration in action
The ITER reactor is not only a scientific milestone but also a triumph of international engineering.
Each of the seven primary member entities, China, Europe, India, Japan, Korea, Russia, and the United States, has played a critical role in constructing the magnet system.
- United States: Built and tested the Central Solenoid and its support structures and contributed 8% of the Toroidal Field superconductors.
- Russia: Delivered the uppermost Poloidal Field magnet and produced 40% of the Poloidal Field superconductors. Also supplied 20% of the Toroidal Field superconductors and critical power delivery infrastructure.
- Europe: Manufactured four Poloidal Field magnets in France, contributed 10 Toroidal Field magnets and produced large volumes of superconductors and Tokamak components.
- China: Supplied one 10-meter Poloidal Field magnet, produced superconductors for four other PF magnets, delivered magnet feeders, and manufactured 18 correction coils for precision plasma control.
- Japan: Provided 43 kilometres of superconductor for the Central Solenoid and built 8 Toroidal Field magnets. Also produced 25% of the Toroidal Field superconductors.
- Korea: Fabricated assembly tooling, four vacuum vessel sectors, thermal shields, and 20% of the Toroidal Field superconductors.
- India: Constructed the massive cryostat housing for the Tokamak, developed cryolines and plasma heating systems, and handled major parts of the cooling infrastructure.
Commenting on the collaboration, Pietro Barabaschi, ITER Director-General, said, “What makes ITER unique is not only its technical complexity but the framework of international cooperation that has sustained it through changing political landscapes.”
“This achievement proves that when humanity faces existential challenges like climate change and energy security, we can overcome national differences to advance solutions.”
“The ITER Project is the embodiment of hope. With ITER, we show that a sustainable energy future and a peaceful path forward are possible.”
Building the foundation for commercial fusion
The scale of ITER’s magnet system is unprecedented. With over 10,000 tonnes of superconducting magnets, 100,000 kilometres of superconducting strands, and a total stored magnetic energy of 51 gigajoules, the infrastructure is designed to test and refine the technologies that will drive future fusion power plants.
By integrating the full range of systems required for industrial-scale fusion, the ITER reactor serves as a real-world proving ground for commercial deployment.
The knowledge and experience gained here will inform the next generation of reactors capable of powering cities without carbon emissions.
This milestone – the completion of the pulsed superconducting magnet system – signals that the era of practical fusion energy is closer than ever, built on global cooperation, technical precision, and an unrelenting pursuit of a cleaner energy future.
