ITER Completes Major Test of 330-Tonne Superconducting Magnet for Fusion Reactor
ITER has successfully completed a major test campaign on its 330-tonne toroidal field coil #17, achieving an energization of 34 kiloamperes (kA). This milestone is a key step in the assembly of the world’s largest fusion reactor.
The D-shaped coil was cooled to 4 Kelvin (minus 269 degrees Celsius) during testing, reaching half of its nominal operating current of 68 kA. This test allowed engineers to observe how the magnet deforms under electromagnetic loads and to compare its performance with structural models.
On October 30, the coil was transferred from the magnet cold test facility to a transport frame. It will be temporarily stored before being moved to ITER’s Assembly Hall for integration into the plasma chamber’s final sector module.
This achievement provides valuable operational experience as ITER prepares for the commissioning of its integrated magnet systems. The magnet cold test facility was specifically designed to evaluate ITER’s superconducting magnets and their supporting infrastructure, including cryogenics, vacuum systems, and power supplies.
The first testing campaign began in May 2026 with toroidal field coil #7, which was energized to 10 kA. This initial phase allowed engineers to assess electrical resistance at the joints and evaluate the system designed to detect a loss of superconductivity, known as a quench.
Testing of coil #17 commenced in August, and reaching 34 kA marked a significant increase in the testing current. Adrien Deydier, ITER’s lead mechanical engineer, stated, “It is an important step to reach 34 kA and to confirm the coil is behaving as predicted by the models.”
Following the successful testing of coil #17, the magnet cold test facility will prepare for testing spare coil #19, which is scheduled to begin cooling to 4 K in April 2027. This next phase will include testing at 34 kA before moving on to full-current trials at 68 kA.
The upcoming campaign will introduce Paschen-tight connections between the in-cryostat feeder and the coil, replicating those planned for the tokamak. This will enable engineers to assess the magnet’s high-voltage ground insulation.
After testing coil #19, the facility will be reconfigured to accommodate poloidal field coil #1, which is another critical component of ITER’s magnetic confinement system. ITER’s toroidal field magnets play a vital role in confining the superhot plasma within the reactor, utilizing 18 D-shaped toroidal field coils, six poloidal field coils, and a central solenoid to generate and control the necessary magnetic fields for fusion experiments.
The cold-testing program aims to identify potential issues before the magnets are integrated into the reactor, thereby reducing risks during commissioning and future operations.
Source: Interesting Engineering