Losses in a high-temperature superconductor exposed to AC and DC transport currents and magnetic fields

The development of high-temperature superconductors (HTSs) is, for the moment, intensive and it is likely that HTSs will be used in different electric devices in a few years. In some of these devices, the conductor will be exposed to both ac and dc transport currents and magnetic fields. In the design of electric devices, the power loss is indeed one of the most important parameters. Therefore, there is a need for models that predict the power loss in an HTS under application-like conditions. In this paper, we present a semiempirical model including a transport current and an applied magnetic field with both ac and dc components. The semiempirical model is mainly based on the critical state theory. The results of the model are compared and found to be in good agreement with experimental results obtained with a calorimetric experimental setup. The power loss was measured on a multifilamentary Bi-2223 tape as a function of transport current and applied magnetic field at a fixed temperature and frequency.