In a monumental step forward for fusion energy, the ITER project has successfully completed the assembly of all components for what is poised to become the world’s largest and most powerful pulsed superconducting electromagnet system. This engineering marvel represents a key milestone in humanity’s quest toward harnessing fusion—the same process that powers our sun and stars—as an abundant, clean, and safe source of energy. The seamless collaboration among over 30 countries demonstrates the immense scientific and geopolitical potential fusion power holds for the future.
The crowning achievement in this endeavor is the fabrication and testing of the sixth and final module of the Central Solenoid, constructed in the United States. This crucial assembly, when integrated with its five sibling modules, will form the electromagnetic heart of ITER’s Tokamak fusion reactor, located in Southern France. Towering 18 meters high and weighing approximately 1,000 tons, the Central Solenoid embodies extraordinary engineering, capable of generating magnetic fields strong enough to lift an aircraft carrier. Its superconducting niobium-tin coils, maintained at cryogenic temperatures of 4.5 Kelvin using liquid helium, enable it to sustain a plasma current of 15 megaamperes over pulses lasting several minutes.
Operating in concert with six massive ring-shaped Poloidal Field magnets provided by Russia, Europe, and China, the Central Solenoid creates an intricate magnetic configuration essential for plasma confinement. This combined magnet system, weighing nearly 3,000 tons, forms an invisible yet powerful electromagnetic cage inside ITER’s donut-shaped Tokamak chamber. The synergy between these elements precisely controls the plasma—a hot ionized gas of hydrogen isotopes—to prevent it from touching the reactor walls, ensuring stable fusion reactions under extreme conditions.
The process inside ITER begins with the injection of a few grams of hydrogen fuel, consisting of deuterium and tritium gas, into the Tokamak’s vacuum chamber. The pulsed electromagnets then initiate an intense electrical current that ionizes the gas, producing plasma at temperatures soaring to 150 million degrees Celsius. This temperature is roughly ten times hotter than the core of our sun, a feat made possible by external heating systems and the exceptional magnetic confinement. At such extreme heat, atomic nuclei collide and fuse, releasing significant energy in the form of heat—a process that promises a sustainable source of power if mastered.
Perhaps one of the most ambitious goals of ITER is to achieve a tenfold energy gain, where the fusion output is at least ten times the input heating power. Specifically, ITER aims to produce 500 megawatts of fusion power from just 50 megawatts of input, allowing the plasma to become “self-sustaining” or “burning.” Reaching this milestone would demonstrate not only the technical feasibility of fusion power but also its potential for commercial energy production on an industrial scale, a revolutionary breakthrough for energy security and climate change mitigation.
Integral to ITER’s success is the international collaboration among its seven members: China, Europe, India, Japan, Korea, Russia, and the United States. This fusion endeavor transcends national boundaries, fostering unprecedented scientific cooperation. Thousands of engineers and scientists across three continents have contributed specialized components, leveraging global expertise to build this single complex machine. The political and technical harmony among ITER partners serves as a beacon of hope and a model for addressing global challenges through unity and shared knowledge.
In the past year alone, ITER reached 100 percent of its construction targets, with key developments such as the insertion of the first vacuum vessel sector module completed three weeks ahead of schedule in April 2025. This accelerated assembly phase reflects not only technological progress but also effective project management and international coordination. Such momentum enhances confidence in ITER’s ultimate goal: to become the world’s first fusion device to produce net-positive energy.
Beyond governmental efforts, the private sector has seen a surge in interest and investment in fusion energy research and development. Recognizing this trend, ITER has proactively engaged with private companies to accelerate innovation and facilitate knowledge transfer. Initiatives launched in 2024 aim to create synergies between public and private fusion programs, enhancing access to ITER’s extensive data, documentation, and global supply chain expertise. Notably, a public-private workshop was held in April 2025 to explore cutting-edge technological innovations for overcoming enduring fusion challenges.
Each ITER member country has made distinct yet complementary contributions based on their capabilities. The United States, for example, fabricated the six module Central Solenoid and produced the complex exoskeleton structural system designed to withstand enormous electromagnetic forces. Japan supplied the niobium-tin superconductor strands crucial for the Central Solenoid modules and manufactured several Toroidal Field magnets. Russia and Europe focus primarily on Poloidal Field magnets and superconducting materials, while China has delivered multiple magnets and critical feeders supplying electrical power and cryogenic cooling. Korea and India contribute precision tooling, vacuum vessel sectors, cryostat, and cooling infrastructure. Together, these contributions epitomize a global fusion supply network unprecedented in scale and complexity.
The technical specifications of ITER’s magnets highlight the staggering engineering involved. The Central Solenoid alone is 18 meters tall, 4.25 meters wide, and weighs about 1,000 tons. It generates a magnetic field strength of 13 Tesla—approximately 280,000 times stronger than Earth’s magnetic field—and stores 6.4 gigajoules of magnetic energy. Poloidal Field magnets vary from 9 to 25 meters in diameter and weigh between 160 to 400 tons each. Toroidal Field coils resemble enormous D-shaped structures standing 17 meters tall and weigh roughly 360 tons each. All superconducting components operate near absolute zero temperatures around 4.5 Kelvin, maintained by sophisticated liquid helium cryogenic systems to ensure zero electrical resistance and efficient power consumption.
With over 10,000 tons of superconducting magnets integrated into the ITER machine, the combined magnetic energy stored reaches an astonishing 51 gigajoules. Fabrication required more than 100,000 kilometers of superconducting wire produced across nine factories in six countries. This monumental undertaking illustrates the unprecedented level of precision manufacturing and quality control essential for realizing fusion’s promise.
ITER stands today not only as a pinnacle of engineering and physics but as a powerful symbol of international scientific diplomacy and shared determination. Its success could usher in a new era of sustainable clean energy, drastically reducing global reliance on fossil fuels and curbing greenhouse gas emissions. As climate change and energy demands escalate, the lessons and technologies emerging from ITER offer vital pathways toward a secure and low-carbon energy future.
In conclusion, ITER’s achievement in completing the world’s largest pulsed superconducting electromagnet system marks a historic milestone for fusion energy research. The project showcases the culmination of international synergy, groundbreaking innovation, and relentless pursuit of a science fiction dream now coming into tangible reality. With assembly underway and private-public partnerships accelerating, the dawn of practical fusion energy seems increasingly within reach—a beacon of hope for generations to come.
Subject of Research: Fusion Energy Technology — Superconducting Magnet Systems for Tokamak Reactors
Article Title: ITER Completes World’s Largest Pulsed Superconducting Magnet System, Advancing Fusion Energy Breakthrough
News Publication Date: April 2025
Web References:
www.ITER.org
Image Credits: General Atomics / ITER
Keywords
Fusion energy, ITER, superconducting magnets, Central Solenoid, Tokamak, Poloidal Field magnets, Toroidal Field coils, plasma physics, magnetic confinement, superconductors, climate change, electrical power generation
