SAN DIEGO, CA – Scientists and engineers at General Atomics have successfully completed the development and testing of six colossal 270,000-pound (approximately 122 metric tons) superconducting magnet modules, destined to form the heart of the International Thermonuclear Experimental Reactor (ITER) in France. This critical milestone brings the global fusion energy project significantly closer to its goal of demonstrating large-scale, carbon-free fusion power.
Each module, part of ITER’s Central Solenoid, is crucial for initiating and maintaining the superheated plasma necessary for fusion reactions. The completion of these components marks a major step forward in the international collaboration to harness the same energy process that powers the sun.
The Central Solenoid: Heart of the ITER Tokamak
The Central Solenoid is the most powerful component of the ITER magnet system, designed to induce the majority of the magnetic flux change required to ignite and sustain the plasma current within the tokamak. Standing nearly 60 feet (18 meters) tall when fully assembled, the Central Solenoid will be the largest and most powerful pulsed superconducting magnet ever constructed.
Engineering Marvel: Construction and Components
Fabrication of these immense modules began in 2015, with each cylindrical unit approximately 4 meters tall and wound with roughly 6 kilometers (3.5 miles) of niobium-tin (Nb3Sn) superconducting cable. This specialized cable-in-conduit conductor, provided by the Japanese Domestic Agency, is essential for achieving the extremely strong magnetic fields (up to 13 Tesla) needed to confine the plasma.
The production process involved meticulous winding, insulation with 25 layers of fiberglass and Kapton sheets, and rigorous testing at cryogenic temperatures (4.5 Kelvin, or -269 degrees Celsius) to simulate operational conditions. The final in-factory testing for each module ensures its performance before shipment to the ITER site in Cadarache, France.
US Contribution to Global Fusion
The United States, through the US ITER project managed by Oak Ridge National Laboratory (ORNL), has been responsible for the design, research and development, and fabrication of the six operational Central Solenoid modules, plus a seventh spare module. General Atomics in Poway, California, served as the subcontractor for this monumental task.
Beyond the modules themselves, US ITER also delivered the “exoskeleton” support structure, comprising over 9,000 individual parts manufactured by eight US suppliers, to enable the Central Solenoid to withstand the immense electromagnetic forces it will generate. The US contribution to ITER also includes 8% of the Toroidal Field magnet superconductors.
ITER’s Progress and Future Outlook
With the completion and ongoing shipment of these crucial Central Solenoid modules, the ITER project continues to advance its assembly phase, which began in 2020. Four of the six modules are already on site and have been stacked, with the fifth currently in transit and the final production module expected later this year.
The international collaboration, involving 35 nations including the European Union, China, India, Japan, Russia, South Korea, and the United States, aims to demonstrate the feasibility of fusion energy as a large-scale, carbon-free power source.
While the project has faced schedule adjustments, a revamped plan announced in July 2024 by ITER Director-General Pietro Barabaschi aims for an initial phase of operations, including deuterium-deuterium fusion, in 2035, followed by full magnetic energy and plasma current operation. This new timeline prioritizes substantial research operations and consolidates tokamak assembly stages, with the ultimate goal of achieving full fusion power in the deuterium-tritium phase. The project is currently over 85% complete towards first plasma.
The successful completion and delivery of these vital 270,000-pound Central Solenoid modules underscore the significant progress being made at ITER, bringing the world closer to a potential era of clean, safe, and virtually limitless fusion energy.
