First strands qualified for ITER Toroidal Field coils

Before the ITER Toroidal Field coils are procured, the superconducting strands that make up the cable need to be qualified for ITER operation. At the Sultan test facility at the fusion institute CRPP (Switzerland), a 3.5 meter conductor sample cabled from strands and produced by the company EAS has been tested with positive results. The conductor used for the sample was fabricated under supervision of the Italian fusion institute ENEA, and the sample was prepared, heat treated and assembled at CRPP.

The test program involves the operation under conditions representative of the operation in ITER of a TF coil. The sample was therefore tested with a current of 68 kA, in the Sultan background magnetic field of 10.8 Tesla, and more then 1000 cycles from zero to full current were applied. The performance of the cable proved to be stable under these tests, and the sample passed the acceptance criteria (5.7 K current sharing temperature after 1000 cycles). The EAS strand is therefore considered qualified for the ITER TF coil conductor. Overload tests at 80 kA and a background field of 11T, which were performed after the cycling, did not show any degradation.

During the next few months, strands of the Parties involved in the TF coil production will undergo the same qualification testing program.