Critical data of some A15 type superconductors in transverse fields up to 230 kOe

Abstract

Critical field curves and quenching curves for the A15 (β-W) type compounds Nb3Sn, V3Si, and V3Ga have been measured. The critical field curves have been extrapolated to zero temperature, and the following zero upper critical fields have been found: 245 kOe for Nb3Sn, 235 kOe for V3Si, and 208 kOe for V3Ga. These values lie between the upper and lower limits given by theories for critical fields not taking into account spin-orbit scattering. Critical currents for Nb3Sn samples with small admixtures of zirconium are higher than for corresponding samples without zirconium. Special samples of Nb3Sn multiwires 522 have still high critical currents in the high-field region up to 230 kOe.