Calculations of AC current losses and AC magnetic losses from the scanning Hall probe measurements for a coated conductor

摘要

We measured the field profiles near the surface of a coated conductor (CC) by using the scanning Hall probe method. The external currents, represented by I-a, or the external fields, represented by H-a, were applied during the measurements. The field was applied in the normal direction with respect to the tape surface. The measured field profiles could be expressed by H(x, X-a), where the variable, X-a, was either I-a or Ha. The x-axis was parallel to the in-plane transverse direction of the CC tape. The CC tape was fabricated by the IBAD-PLD method. The applied field (current), H-a (I-a), was decreased stepwise from H-peak to -H-peak (from I-peak to -I-peak). From H(x, X-a), we calculated the current profile, J(x, X-a), by the iterative inversion method. From J(x, X-a) and the corresponding flux densities, B(x, X-a) we calculated the AC current loss, Q(C)(I-peak), and the AC magnetic loss, Q(M)(H-peak), for various values Of I-peak and H-peak, respectively. The characteristic functions were defined by f(C) = pi Q(C)/mu I-0(c)2 and f(M) = pi Q(M),/mu 0I(c)(2), where I-c is the critical current. We found that the calculated values of f(C) (f(M)) were similar to the experimental values of f(C) (f(M)) which were directly measured for the IBAD-PLD CCs. On the other hand, the values of f(C) (f(M)) were smaller than (larger than) the values estimated from the experimentally observed Q(C) (Q(M)) in RABiTS (TM)-MOD CCs.