In a major breakthrough for sustainable energy, the international ITER project has completed construction of the world’s largest superconducting magnet system
The system is designed to contain superheated plasma and produce ten times more energy than it consumes.
It is the “electromagnetic heart” of the project’s Tokamak fusion reactor, which was created in collaboration with more than 30 countries.
A Milestone for Clean Energy
ITER (pronounced “iter”) is a global project bringing together more than 30 nations to demonstrate that fusion energy can be a safe, limitless, carbon-free source of energy.
The final piece of the puzzle is the Central Solenoid, a giant magnet built and tested in the United States that is so powerful it could lift an aircraft carrier.
It will be installed at the ITER facility in southern France, along with six other large ring-shaped magnets manufactured by Russia, Europe and China.
Together, these magnets weigh almost 3,000 tons and form the heart of the Tokamak, a donut-shaped reactor that attempts to reproduce the energy of stars here on Earth.
How Does This Magnet System Work?
Fuel: A small amount of hydrogen gas (deuterium and tritium) is injected into the giant chamber of the Tokamak.
Creating the plasma: The magnet system sends an electric current that transforms the gas into plasma, a cloud of charged particles.
Controlling the plasma: The magnets create an “invisible cage” that holds and shapes the plasma.
Heating: External systems heat the plasma to 150 million degrees Celsius, ten times hotter than the core of the Sun.
Fusion: At this temperature, the nuclei of the plasma particles come together, releasing an enormous amount of energy.
The Power of Fusion
When fully operational, ITER is expected to generate 500 megawatts of fusion energy using just 50 megawatts to heat the plasma, or ten times more energy than it consumes.
At this point, the plasma becomes a “self-sustaining flame,” heating itself.
ITER is like a giant laboratory that tests everything needed to produce fusion energy on an industrial scale, providing knowledge to participating countries.
A Symbol of Global Cooperation
In addition to technical advancement, ITER is an incredible example of unity among nations.
Its seven core members-China, Europe, India, Japan, Korea, Russia, and the United States-work together, with thousands of scientists and engineers from hundreds of factories on three continents.
“What makes ITER unique is its technical complexity and the international cooperation that keeps it alive, even with political changes,” says Pietro Barabaschi, ITER’s director general.
“This shows that when faced with challenges such as climate change and energy security, we can overcome differences to find solutions.”
Progress and Collaboration with the Private Sector
In 2024, ITER achieved 100% of its construction goals.
Most of the components have been delivered, and the Tokamak is in the assembly phase.
In April 2025, the first vacuum chamber module was installed in the Tokamak, three weeks ahead of schedule.
In the past five years, private companies have started to invest more in fusion research.
In 2023, ITER decided to share its knowledge with these companies to accelerate the development of fusion.
In 2024, a project was launched to collaborate with the private sector, sharing data, documents and experience.
In April 2025, ITER organized a workshop with companies to discuss innovations that will help solve the remaining challenges of fusion.
Country Contributions
Under the ITER agreement, each member country pays the majority of the costs by supplying components, which benefits its own industries and creates a global supply chain for fusion.
Europe, as host, covers 45% of the costs, while China, India, Japan, Korea, Russia and the United States contribute 9% each.
All have access to 100% of the intellectual property generated.
United States: Built the Central Solenoid, with six modules, plus a spare, as well as a support structure to withstand extreme forces.
It also supplied 8% of the superconductors for the toroidal magnets.
Russia: Delivered a 9-meter poloidal magnet, 40% of the superconductors for poloidal magnets and 20% for toroidal magnets, as well as conductor bars and plugs for the vacuum chamber.
Europe: Produced four poloidal magnets, 10 toroidal magnets, 5 of the 9 vacuum chamber sectors and part of the superconductors.
China: Manufactured a 10-meter poloidal magnet, 65% of the superconductors for poloidal magnets, 8% for toroidal magnets, 18 correction magnets and 31 feeders for the magnets.
Japan: Supplied 43 km of superconductors for the Central Solenoid, 8 toroidal magnets (plus one spare) and 25% of the superconductors for these magnets.
Korea: Produced tools for assembling components, 20% of the toroidal superconductors, heat shields and 4 sections of the vacuum chamber.
India: Built the cryostat (a 30-meter chamber that houses the Tokamak), cooling tubes, the cooling water system and parts of the plasma heating.
ITER Magnet Specifications
Central Solenoid:
– Height: 18 meters
– Diameter: 4.25 meters
– Weight: “1,000 tons
– Magnetic force: 13 Tesla (280,000 times stronger than Earth’s magnetic field)
– Stored energy: 6.4 Gigajoules
– Material: Niobium-tin (Nb”Sn) superconductors, manufactured in Japan
– Cooling: Kept at -269°C with liquid helium
– Poloidal (ring-shaped) magnets:
– Diameters: From 9 to 25 meters
– Weight: From 160 to 400 tons
– Manufactured by Russia, Europe and China
– Material: Niobium-titanium (NbTi) superconductors
– Cooling: -269°C with liquid helium
– Toroidal (D-shaped) magnets:
– Size: 17 meters high x 9 meters wide
– Weight: “360 tons each
– Manufactured by Europe and Japan
– Material: Niobium-tin superconductors (Nb”Sn)
– Cooling: -269°C with liquid helium
– Correction Magnets and Feeders:
– Correction magnets: Made by China, adjust the plasma stability.
– Feeders: Also from China, carry electricity, liquid helium and signals to the magnets.
The ITER magnet system weighs 10 thousand tons and uses more than 100 thousand km of superconducting wires, manufactured in 9 factories in 6 countries.
This project is a giant step towards making fusion energy a reality, showing that global collaboration can create a cleaner, more sustainable future.
Published in 05/11/2025 06h17
Text adapted by AI (Grok) and translated via Google API in the English version. Images from public image libraries or credits in the caption. Information about DOI, author and institution can be found in the body of the article.
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