Field models of high-temperature superconductor devices for magnetic levitation

摘要

Purpose - The purpose of this paper is to describe a twofold methodology for evaluating the force between field excitation system and bulk in a magnetic-levitation device based on high-temperature-superconductors (HTS). The paper focuses on two-dimensional field models for HTS bulks. As far as field analysis is concerned, the finite-element method in two or three dimensions is used. Alternatively, the conformal mapping approach provides a flexible and accurate calculation tool, useful for the optimization of superconducting bearings. Design/methodology/approach - Powerful mapping algorithms, developed recently for Schwarz-Christoffel-like transformations, have proven successful in analyzing the fields, both in the activation and in the operation condition of superconductor devices. Findings - Assuming small displacements of the superconductor sample with respect to the excitation magnets, the force-displacement curve was obtained for operational field cooling via Schwarz-Christoffel maps. Originality/value - The specific theory used is the substitution theorem for magnetic fields, along with its capability to take complex geometries into account, making it possible to model devices for real-life applications. Using only a scalar potential, the procedure proposed for computing fields proves, in the conformally-mapped plane, the superposition method already introduced in FEM-based models.