Effect of micro and macrononhomogeneity of Nb3Sn strands on E–I characteristics

The peculiar feature of Nb3Sn diffusion grown layers is the presence of intrinsic regions, which differ by the composition and microstructure. These regions can be treated as Nb3Sn macrononhomogeneity. Internal stresses and composition fluctuations in Nb3Sn grains can be associated with the micrononhomogeneity. Both types of the inhomogeneites exhibit itself in the shape of superconducting transition characteristics. In the present work voltage–current and voltage–temperature curves were studied for Nb3Sn model flat conductor and ITER type multifilamentary strands.