LAUSR

The Nb3Sn strand is the presently most widely used high field superconductor. However, one important fact is that the transport properties of an Nb3Sn strand will degrade obviously when it is subjected to high mechanical loads. Based on the dispersed distribution of cracks in the bronze strand due to a high axial tensile strain, we propose an analytical strand model to describe the influence of cracks on the critical current of the Nb3Sn strand. The dependence of the critical current Ic of the strand on crack density is investigated theoretically. It is shown that the calculation results by this model agree with the experimental data. The influence of filament-to-matrix resistance rc on transport degradation is also discussed since rc is a key parameter for the total voltage calculation and its realistic value is of great importance for accurate results. We also compared the influence of dispersed and collective cracks on transport properties with specific conditions.