Simulation of a compact trapped field magnet using a (RE)BCO bulk and an HTS coil during a PFM process
Résumé
A compact trapped field magnet (TFM), also called a superconducting permanent magnet, can be employed in a variety of applications, e.g. as flux-pinning docking interface (FPDI) for satellites in space [1], as active elements in robots and machinery. The TFM can be energized by high currents flowing through a high temperature superconducting (HTS) coated conductor wrapped around a (RE)BCO bulk. The magnetization of the unit, consisting of both the HTS bulk and the coil, is achieved by the so-called pulsed field magnetization (PFM) process, where pulsed currents are flowing in the coil, which is cooled together with the bulk to the operating temperature. The simulation of the unit is achieved with a coupled thermal and magnetic finite element model solved with COMSOL Multiphysics. The magnetic model is based on an efficient coupling between the A-H and T formulations. The coupling with the thermal model is given by the dependence of the critical current density in the bulk and in the HTS tape on the temperature in addition to the dependence on magnetic flux density. The main objective of this work is to accurately reproduce the measurements observed in the experiment. We will also highlight the conditions under which the coil contributes to reinforce the magnetic flux trapped by the bulk, where an example is given in Fig. 1.