Europe has completed the production of its share of niobium-tin (Nb3Sn) superconducting wire that will be used for ITER’s toroidal field coils.

The wire is the key component that will allow the TF coils to achieve the magnetic field of 12 T required for the plasma to be confined in the ITER machine. Each strand has a diameter of less than 1 mm, but can sustain very high currents (around 200 A) when cooled down -269 degrees Celsius.

Europe was responsible for procurement of 97 tons (20.2%) of ITER’s toroidal field strands. The wire, some 20,000 km in length, was fabricated by Bruker European Advanced Superconductors and Oxford Superconducting Technology. It has now been tested and approved by the European Domestic Agency, Fusion for Energy, and cleared by the ITER Organization.

The superconducting wire from the two European manufacturers will now be used to fabricate cables for the European toroidal field coil cable-in-conduit conductor (CICC) lengths.

Fifty percent of conductor unit lengths have already been produced and delivered to ASG Superconductors SpA, the Italian facility in charge of manufacturing the toroidal field coil winding packs, according to ITER. The remaining conductor lengths will be finalized in 2015.

In addition to Europe, Japan, Russia, Korea, China and the USA are also contributing TF conductor. Europe is the third ITER Domestic Agency, after Korea and Japan, to complete toroidal field strand production and all related ITER Organization control points.


Photo: The final inspection on the completed wire at an eddy current test station at Bruker EAS, in Germany. (Photo courtesy of Bruker EAS GmbH.)