Calculation of AC Magnetic Losses from the Experimental Field Profiles in a Coated Conductor Under Various External Fields and Temperatures

We developed a method for the estimation of AC loss in superconducting tapes. First we measured the field profiles, H(x, H_a), near the surface of a coated conductor (CC) using the scanning Hall probe method. Here, the x axis was parallel to the in-plane transverse direction of the CC tape and H_a is the external field applied in normal direction with respect to the tape surface. Then from H(x, H_a), we calculated the current profiles, J(x, H_a), by the inversion method. From J(x,H_a) and the corresponding flux densities, we calculated the hysteretic energy losses per cycle, Q_M ldr H_a was decreased from H_peak to -H_peak stepwise, and the temperatures were 77 K and 72 K. We estimated Q_M for various values of H_peak. We calculated the dimensionless characteristic function, g, which are defined by Q_M/(mu₀I_c ²). Here I_c is the critical current. Our g is similar to the Brandt´s theoretical g although the current profile, J(x, H_a), is somewhat different.