Performance of Japanese Nb Sn Conductors for ITER Toroidal Field Coils

The Nb Sn cable-in-conduit conductors for the ITER TF coils are fabricated using the latest high performance strands. The strands made by bronze and internal-tin methods are used for the conductors with a void fraction of 29% and 33%, respec- tively. Superconducting performance of the conductors was mea- sured at the operating condition of the TF coils. The measured cur- rent sharing temperatures Tcs are 6.3-6.6 K for the bronze and 5.6-6.1 K for the internal-tin. The Tcs of the conductor with void fraction of 29% is 0.1-0.3 K higher than the conductor with a void fraction of 33%. It is shown from the results that the strain on the cable is between 0.7% and 0.75% and the n-values are between 4 and 6, much smaller than the n-values of strands. Index Terms—Current sharing temperature, ITER, Nb Sn CICC, SULTAN, toroidal field coil.