EFFECTS OF DIFFUSION BARRIER ON THE MAGNETIZATION CYCLES OF NB3SN STRAND FOR ITER CONDUCTOR

High performance Nb3Sn strands for the high field ITER (international Termonuclear Experimental Reactor) magnets have been manufactured usin g diffusion barriers among the multifilamentary cores and the stabiliz ing copper, In the conductor development programme, billets using a si ngle Ta or a double NbV barrier have been assembled, The barrier is sh own to have an influence on magnetization characteristics. The measure ments 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 J(c).