AC loss and current distribution measurement for superconducting tapes

We made a co-axial copper tube measurement device in order to measure AC losses of HTS tapes. This device can minimize the external disturbance for high accuracy measurement. Also it is easy to fix the tape inside the copper tube. We used a linear amplifier in order to measure the voltage in high accuracy because the transport current was large. The voltage taps are located at the center and the edge of the tapes to measure the voltage drop on the samples. Our experimental data show that the inductive voltages are proportional to the frequency, and therefore this means that the main loss depends on hysteresis loss. In this study, the AC loss characteristics of twisted Bi-2223 tapes and untwisted tapes carrying AC transport current in self field is investigated. The magnetic flux generated by the transport current flowing in the HTS tape can be measured by using the same experimental setup. If the superconducting filament is twisted to reduce the AC losses, a relatively higher magnetic flux is induced at low frequencies, this is measured by winding the measuring wire around the tape - winding pick up method.