Set-up for calorimetric measurements of the AC losses in HTS tapes due to longitudinal magnetic fields and transport currents

Abstract

For the design of power applications based on high-temperature superconducting (HTS) tapes, knowledge of the AC losses is needed. In most such applications the HTS tape is exposed to a magnetic field oriented perpendicular to the current path. However, in certain applications, the HTS tape is exposed to a field oriented in parallel with the current path; a longitudinal magnetic field. To study the AC losses due to combinations of longitudinal magnetic fields and transport currents, we have developed a calorimetric measurement system. Current in a solenoid generates the magnetic field along the straight sample, which simultaneously can be fed with a DC or an AC transport current. The system operates at liquid nitrogen temperature. The AC losses are determined by the temperature rise of the sample. For calibration the sample is fed by a DC current exceeding the critical current. Measurement results are presented for a Bi-2223 HTS tape.