FIRST RESULTS OF STRAIN EFFECTS ON I-c OF Nb3Al CABLE IN CONDUIT FUSION SUPERCONDUCTORS

The effect of axial strain, epsilon(a), on the critical current, I-c, of Nb3Al "Cable in Conduit" (CIC) subconductors has been measured firstly at I-c <= 10 kA and a magnetic field of B = 12 T at KfK, Karlsruhe. Like comparable Nb3Sn CIC cables this conductor exhibits a maximum of I-c at epsilon(a) approximate to 0.7 %, but the degradation of I-c at epsilon(a) = 0 and B = 12 T being only 20% for Nb3Al in comparison to 50 % for the Nb3Sn cables. Furthermore, the I-c vs epsilon(a) characteristic behaves completely reversible under both loaded and unloaded conditions up to the measured strain of epsilon(a) = 1.7%. The Nb3Al CIC subconductor has been developed within the 10 kA/12 T class for fusion magnets at JEARI. A tripleted cable consisting of 36 strands was inserted into a circular stainless steel conduit with 30 % void fraction and then heat treated. JR processed Nb3Al wires were used for the basic strands.