Properties of Nb3Sn Superconductors of Various Designs

To manufacture a high field magnet it is required to have Nb3Sn superconductors with high current-carrying capability in magnetic fields up to 18 T. For example, CERN has chosen Nb3Sn together with HTS as potential material for high field magnet of Future Circular Collider (FCC) project. Also, these superconductors must have an RRR of more than 150 and a low level of energy loss. One of the ways to achieve high current density is to use Internal Tin method to manufacture Nb3Sn superconductors. In this paper, Internal Tin Nb3Sn strands with 37, 54, 84 and 120 sub-elements are studied. Using TEM and SEM analysis, the structure and elemental composition of the superconducting layer were investigated. The analysis of the measurement results of electrophysical parameters showed that with an increase in the number of subelements from 37 to 120, at the same heat treatment mode of 370 degrees C, 100 h + 665 degrees C, 40 h, the critical current density measured in the range of magnetic fields from 12 to 23 T for strands of different designs practically does not changes significantly, and the RRR parameter decreases from 280 to 110 units and the effective filament diameter decreases from 139 to 70 micrometers.