Effects of tin-diffusion barriers on hysteresis loss and coupling current loss in bronze-processed Nb₃Sn multifilamentary composites

A.c. losses for a practical bronze-processed Nb₃Sn multifilamentary composite were measured over a wide range of amplitudes (O ≤ B_m ≤ 14 T,O ≤ B_dc ≤ 10 T) in transverse magnetic field with trapezoidal wave forms. The composite had a Nb or Ta barrier for ptoecting the Cu stabilizer from Sn diffusion. The observed results were analysed theoretically and a quantitative agreement was obtained over the whole measured range of amplitudes in both types of samples with Nb and Ta barriers. Existing expressions for the hysteresis loss in multifilamentary composites have been known to show deviation by more than a factor of 2 from the observed data. No theoretical discussion has previously been presented for the effects of a Nb barrier.