World’s largest tokamak cools 330-ton superconducting magnet for fusion plasma

At nearly 270 degrees below zero Celsius, a 330-ton magnet coil is being pushed to its absolute limits, and scientists say that's exactly the point.

At ITER's newly activated Magnet Cold Test Facility, engineers are running high-current trials on the massive superconducting coils destined for the world's largest experimental fusion reactor. After a 12-day cooling process, the team will subject each coil to electrical currents reaching 68,000 amperes over four to six months.

The stakes are high. If temperatures or magnetic forces exceed strict thresholds, the material undergoes a "quench," suddenly reverting to a resistive state and releasing dangerous heat. These test runs are designed to catch exactly that.

But ITER Director-General Pietro Barabaschi sees a bigger picture. "This is important for ITER as well as an example of how ITER can support the wider fusion ecosystem by creating knowledge, infrastructure, and operational experience that others can use," he said.

Once ITER finishes its own tests, private fusion companies will get access to the facility.