Effects of diffusion barrier on the magnetization cycles of Nb(3)Sn strand for ITER conductor

High performance Nb(3)Sn strands for the high field ITER (International Thermonuclear Experimental Reactor) magnets have been manufactured using diffusion barriers among the multifilamentary cores and the stabilizing copper. In the conductor development programme, billets using a single Ta or a double NbV barrier have been assembled. The barrier is shown to have an influence on magnetization characteristics. The measurements on samples from the two types of strands are shown and analyzed to correlate them with the magnetic behaviour of Nb at low field. The results show that at low field hysteretic losses are greatly increased by the pure Nb of the barrier. At high field, losses of samples with Ta barrier are larger, due to their higher Jc.