The ITER Organization has announced the completion and final delivery of its Central Solenoid (CS), one of the most complex and powerful magnet systems ever constructed. The final of six modules arrived at the ITER site in southern France, marking the culmination of a two-decade international effort. The 18-meter-tall, 1,000-tonne magnet is now fully assembled within the ITER cryostat. As the primary inductive driver for the tokamak's plasma, the Central Solenoid's completion is a critical prerequisite for the machine's assembly and eventual first plasma operations. The system was designed and fabricated under the direction of US ITER, with manufacturing led by General Atomics. Source: ITER

Functionally, the Central Solenoid acts as the backbone of the ITER tokamak, inducing a powerful current within the deuterium-tritium fuel to initiate, shape, and sustain the plasma. The system is designed to ramp up a current of 45,000 amperes, generating a peak magnetic field of 13 Tesla. This powerful field swing is capable of storing and releasing up to 5.5 gigajoules of magnetic energy, which drives the plasma current. The CS is composed of six independent coil modules stacked vertically, allowing for precise control over the plasma's magnetic flux. This control is vital for achieving the high-confinement modes necessary for net energy gain. Source: ITER

The system is designed to ramp up a current of 45,000 amperes, generating a peak magnetic field of 13 Tesla.

The fabrication of the Central Solenoid was a significant engineering and logistical challenge, involving contributions from multiple ITER member nations. The design and R&D were managed by US ITER at Oak Ridge National Laboratory. The individual modules were manufactured by General Atomics in California using 40 kilometers of niobium-tin (Nb3Sn) superconducting cable. This advanced conductor, which required a multi-stage heat treatment process, was produced by a consortium of nine companies across five countries. The successful completion represents a major validation of the international collaboration model that underpins the entire ITER project and provides critical manufacturing experience for future fusion power plants. Source: ITER

With the Central Solenoid now in place, project teams will proceed with the integration of surrounding components, including the thermal shield and the vacuum vessel sectors. The CS must be precisely aligned with the toroidal and poloidal field coils to ensure the magnetic topology required for stable plasma confinement. According to ITER Director-General Pietro Barabaschi, the magnet's completion is a "historic moment" for the project. The next major steps involve connecting the extensive cryogenic, power, and instrumentation lines before the final closure of the cryostat, moving the multi-billion-dollar experiment closer to its operational phase. The performance of this magnet will be a key determinant of ITER's ability to achieve its scientific goals, including a plasma energy gain (Q_plasma) of 10. Source: ITER