The Japanese Domestic Agency for the ITER project, managed by the National Institutes for Quantum Science and Technology (QST), has announced the successful completion of a full-current cryogenic test for one of the project's toroidal field (TF) coils. The test, conducted in collaboration with manufacturer Toshiba Energy Systems & Solutions at a dedicated facility operated by the French Alternative Energies and Atomic Energy Commission (CEA) in Saclay, France, confirmed the coil's performance under operational conditions. The niobium-tin (Nb3Sn) superconductor coil was cooled to minus 269 degrees Celsius and energized to a current of 10,000 amperes, meeting a critical validation gate before its shipment to the ITER construction site. Source: ITER

This specific coil is the first of nine TF coils Japan is contributing to the international fusion energy experiment. The full ITER tokamak requires 18 TF coils plus one spare, with Europe's Fusion for Energy agency responsible for the other ten. These D-shaped magnets are immense, standing nearly 17 meters high and weighing over 300 tons each. Their primary function is to generate a powerful magnetic field to confine the superheated D-T plasma within the vacuum vessel. The successful test of this production unit provides crucial validation of the complex manufacturing and quality assurance processes developed over more than a decade by QST and Toshiba. Source: ITER

This specific coil is the first of nine TF coils Japan is contributing to the international fusion energy experiment.

The test procedure involved placing the coil inside a large cryostat at the CEA facility, where it was gradually cooled with helium to its superconducting state just a few degrees above absolute zero. Once at temperature, engineers ramped up the electrical current to the 10,000 A operational target. This process verifies the integrity of the superconducting strands, the insulation, and the structural support systems under the immense electromagnetic forces generated at full field. Passing this test is a non-negotiable prerequisite for any magnet's installation into the main tokamak assembly, as post-installation repairs would be extraordinarily difficult and costly. Source: ITER

Successfully energizing a production TF coil to its design current is a significant de-risking event for the entire ITER magnet system, which is arguably the most complex and technologically demanding aspect of the machine. The TF coils are designed to produce a magnetic field of 11.8 Tesla on the plasma axis, storing a total of 41 gigajoules of magnetic energy when fully energized. This test provides high confidence that the Japanese-supplied coils will meet the stringent performance requirements for achieving and sustaining a burning plasma. It represents a major hardware contribution from one of the key international partners, advancing the overall project's assembly phase. Source: ITER

Following this validation, the tested coil will be prepared for transport from France to the ITER site in Cadarache for integration into the tokamak pit. The remaining eight coils from Japan, along with the ten being manufactured in Europe, will undergo similar individual testing protocols before they are accepted for assembly. This component-by-component verification is fundamental to the project's staged assembly strategy, ensuring that each of the millions of parts in the massive fusion device performs as designed. The steady arrival and acceptance of these major magnet components is a key indicator to watch for progress on the revised ITER construction timeline. Source: ITER