Construction of combined models of the properties of bulk high-temperature superconducting materials

Abstract

The article contains the results of research that was aimed at improving the models of properties of bulk high-temperature superconducting (HTS) materials, which are necessary for numerical analysis of electromagnetic fields in electrical devices containing elements of high-temperature superconductors. Approximating combined models for a set of transport and bound currents are considered, which are determined, respectively, by the resistive model for currents and the nonlinear hysteresis model for the magnetization. The model of transport currents is based on the known types of the critical-state model. The material-magnetization model is composed for a set of magnetic moments of elementary superconducting cylinders with diameters that are much smaller than their length, which are oriented in the direction of the principal anisotropy axis of the material. The approximation to the actual conditions is realized by the statistical characteristics that specify the possible changes in the critical current density, the critical field strength, and the spatial orientation of the basic axes of the elementary cylinders. The results of studies of a laboratory model, which consists of a cylindrical HTS element and an annular permanent magnet, are presented and compared with the results of electromagnetic-field calculations according to the proposed models of properties.