The final module of the ITER central solenoid has been completed at Oak Ridge National Laboratory (ORNL), marking a significant manufacturing milestone for the international fusion project. This component is the last of seven modules—six operational and one spare—that will be stacked to form the core of the ITER tokamak. The completed solenoid will stand 18 meters tall, weigh 1,000 tons, and is designed to generate a peak magnetic field of 13 Tesla. Its primary function is to induce a powerful current within the D-T plasma, initiating the discharge and helping to confine and shape it during operation. The module's completion concludes a nearly decade-long fabrication process in the United States, a key contribution to the multinational effort. Source: SlashGear

Each module consists of niobium-tin (Nb3Sn) superconducting cables, which must be cooled to 4.5 Kelvin to operate without electrical resistance. The central solenoid will store approximately 6.4 gigajoules of magnetic energy, which it will discharge in pulses to drive up to 15 million amperes of current in the plasma. This powerful induction is essential for ohmic heating, the initial phase of bringing the plasma to the extreme temperatures required for fusion. The magnet's pulsed operation capability is critical for the long-pulse, high-performance scenarios planned for ITER, which aim to demonstrate a net energy gain, or Q_plasma > 10, for hundreds of seconds. The successful fabrication and testing of these complex modules represents a major step in validating the magnet technology for future fusion power plants. Source: SlashGear

Each module consists of niobium-tin (Nb3Sn) superconducting cables, which must be cooled to 4.5 Kelvin to operate without electrical resistance.

The manufacturing process for the central solenoid modules was a complex logistical and engineering challenge. It involved winding over 5 kilometers of niobium-tin superconductor into precise coils for each module. The coils then underwent a multi-stage heat treatment process lasting several weeks to form the superconducting material, followed by being encased in a robust stainless steel structure. The entire assembly was then insulated and prepared for cryogenic operation. This work, managed by US ITER at ORNL, involved collaboration with industrial partners to ensure the components met the stringent requirements for performance and reliability under extreme electromagnetic forces and thermal loads. The project falls under the purview of the U.S. contribution to the international ITER agreement, a cornerstone of public-sector fusion research. Source: SlashGear

With the completion of this final module, the focus shifts to transportation and final assembly at the ITER site in Cadarache, France. The 1,000-ton magnet will be shipped in its constituent modules and painstakingly stacked and integrated into the heart of the tokamak assembly. The successful operation of the central solenoid is a prerequisite for achieving first plasma at ITER. Its performance will be a key determinant of the machine's ability to reach its scientific goals, including sustaining a burning plasma and testing key technologies like tritium breeding blankets. The completion of this major U.S. hardware contribution keeps the overall project on its revised construction and assembly timeline, with researchers watching closely for the start of integrated commissioning of the machine's core systems. Source: SlashGear