Experimental and numerical investigation of flux trapping in bulk YBCO under different permanent magnet configurations

This study investigates flux trapping in bulk YBaCuOx (YBCO) high-temperature superconductors (HTS) under various permanent magnet configurations (PMCs) through both experimental and numerical methods. A finite element method (FEM) based on the H-formulation of Maxwell's equations is employed to simulate the HTS-PM interaction, showing good agreement with experimental results in peak trapped flux density values. The maximum trapped flux densities for PMC-1, PMC-2, PMC-3, and PMC-4 were measured as 207 mT, 359 mT, 392 mT, and 478 mT, respectively, demonstrating the significance of PMC design in optimising flux trapping in HTS materials. Enhanced flux trapping was observed with configurations including additional permanent magnets, such as PMC-2 and PMC-4, yielding trapped flux efficiencies of 77.5 % and 55.0 %, respectively. Obtained results in trapped flux efficiency are very impressive as compared to a value of 23 % trapped flux efficiency in literature in which a solenoid magnet with a 3 T peak value of magnetic flux density is used to trap a magnetic field in the HTS. The magnetic flux trapping methodology of this research is very effective for magnetic bearing applications with self-stabilisation in which high magnetic fields are not needed since it doesn't need any magnetic field sources with complex structures, such as coils, to facilitate the magnetic field trapping in the HTSs.