In a step toward clean, limitless energy, the ITER nuclear fusion project has announced the completion of its central solenoid, the most powerful pulsed magnet ever built, so strong it could theoretically levitate an aircraft carrier. This six-part magnet lies at the heart of the reactor’s ability to confine plasma and could usher in a new era of fusion power.
Fusion energy mimics the process powering the sun—fusing atomic nuclei to release vast amounts of energy. But to initiate such reactions on Earth, scientists must create and confine plasma at temperatures reaching 150 million°C—ten times hotter than the sun’s core. No physical material can withstand this heat, so scientists use magnetic fields to contain the plasma in a floating, donut-shaped chamber known as a Tokamak.
That’s where the central solenoid comes in. Standing 13 meters tall, 4 meters wide, and weighing nearly 3,000 tons, this superconducting magnet will work with six ring-shaped magnets to create a magnetic cage around the burning plasma, suspending it for up to 500 seconds, long enough to sustain energy-generating reactions. With a stored magnetic energy of 6.4 gigajoules, it generates forces of 60 meganewtons, twice the force needed to launch a space shuttle.
ITER (International Thermonuclear Experimental Reactor), a collaboration among 30 countries, is the largest fusion experiment in history. Its goal is to demonstrate a net energy gain, producing 500 megawatts of power from just 50 megawatts of input. This ratio marks the critical threshold at which the fusion reaction becomes self-heating, transitioning into what’s known as burning plasma, a condition necessary for practical power plants.
With the solenoid fully completed and the reactor now entering its assembly phase in southern France, ITER has hit 100% of its 2024 construction targets and even beat a 2025 milestone ahead of schedule.
Europe contributes 45% of ITER’s funding, with China, India, Japan, Korea, Russia, and the U.S. covering the remainder. Despite geopolitical tensions, scientists and engineers from rival nations have worked side by side to pursue what ITER Director-General Pietro Barabaschi calls a “solution to existential threats” like energy security and climate change.
“This achievement proves that when humanity faces existential challenges, we can overcome national differences to advance solutions,” Barabaschi said.
