Skip to main content

Central Solenoid

The US is responsible for 100% of the central solenoid (CS) magnet, including design, R&D, fabrication of 7 CS modules using supplied conductor (from Japan), associated structure, assembly tooling, bus extensions, and cooling connections.

The center solenoid is at the heart of the ITER tokamak.
The central solenoid is at the heart of the ITER tokamak. It both initiates plasma current and drives and shapes the plasma during operation. Image: US ITER

The central solenoid serves as the backbone of the ITER magnet system. The CS induces the majority of the magnetic flux change needed to initiate the plasma, generate the plasma current, and maintain this current during the burn time. The CS is made of six independent coil packs that use a niobium-tin (Nb3Sn) cable-in-conduit superconducting conductor, held together by a vertical pre-compression structure. The conductor will be produced in unit lengths up to 910 m. The US is responsible for the 6 modules of the CS, a spare module, and the structure that ties them together and links these modules to the rest of the magnet system.

How are we building one of the world's largest superconducting electromagnets for ITER? Watch Building the Heart of ITER.


For more information, contact Graham Rossano, US ITER Project Office Magnet Systems Team Leader (Acting), Oak Ridge National Laboratory, | 865-576-0104.

Fact Sheet

One module in packaging; one module ready to package

First-of-a kind superconducting magnet en route to ITER site

The first of six superconducting magnet modules for the ITER central solenoid left General Atomics’ Magnet Technologies Center in Poway, California for the ITER site in France. The second module will depart later this summer. The international ITER fusion facility under construction in France has already begun initial tokamak assembly activities; the central solenoid is expected to be installed in 2023.

CS piping

Strong bonds: MPEX magnet system benefits from US ITER expertise

As Oak Ridge National Laboratory’s Material Plasma Exposure eXperiment (MPEX) prepares for the start of fabrication, ORNL’s Phil Ferguson credits US ITER staff for sharing hard-earned expertise to help jump-start the design of the MPEX superconducting magnet system.

Climax technician works on CS piece

Central solenoid structures and assembly tooling team innovates to get the job done

Building the Heart of ITER
The team is nearing completion of the delivery of critical support structures that will surround and stabilize the central solenoid.

Central solenoid module in test station

First central solenoid module gets clean bill of health

After enduring a battery of rigorous tests, the first of seven superconducting magnet modules that will make up the heart of the ITER international fusion reactor earned a clean bill of health.

Turnover of module 1 of the central solenoid at General Atomics

Fabrication complete on 1st of 7 central solenoid modules

When ITER begins operations in 2025, its plasma will be initiated by the largest stacked pulsed superconducting magnet ever built—the ITER central solenoid. The US ITER magnets team, based at Oak Ridge National Laboratory, is overseeing the fabrication of the central solenoid modules, support structures, and assembly tooling. A major milestone was reached this spring when vendor General Atomics completed fabrication of the first of seven modules.

"General Atomics has done an outstanding job to reach the difficult and important milestone of completing module 1 fabrication," said Wayne Reiersen, US ITER Central Solenoid Magnets Team Leader. "This is the culmination of an eight-year effort involving concurrent engineering of the module design, the creation of a facility in which these powerful superconducting magnets could be built and tested, the qualification of the manufacturing processes, and the building of this first-of-a-kind module."

Source: ITER Newsline

A lower key block support with a technician at Petersen, Inc.

Delivery Begins of Lower Support Components for the “Heart of ITER”

Lower key blocks for the central solenoid are now being delivered to the ITER site

US ITER has started delivery of lower support structures for the central solenoid, the world’s largest electromagnet that will be at the center of the ITER fusion machine. The support structures provide a secure base and cage for the central solenoid in the face of thousands of tons of force. The first delivery, a lower key block weighing over 6 tons, was delivered in February to the ITER site in St. Paul-lez-Durance, France. Eight more lower key blocks are now being shipped. A total of 18 upper and lower key blocks will be delivered by the end of the year.