Enhancement of YBCO superconductor magnetic bearing capability by using multiple bulks

Five well-textured single grain YBCO rectangular samples, four of them 13.5 x 13.5 x 7.5 mm3 and one of them 27.4 x 27.4 x 7.5 mm3 in dimensions, were fabricated by top-seeded melt growth (TSMG) method using Nd-123 seeded. These samples were used to investigate the relationship between levitation force and guidance forces between the individual YBCO bulk and their different arrangements and involve permanent magnet (PM) and traditional monopole permanent magnetic guideway (PMG) for the high-Tc superconducting magnetic bearing applications. The levitation and guidance forces of the samples were experimentally measured using a cryogenic load cell setup by a custom-designed three-axis magnetic force measurement system. Additionally, twodimensional finite element model based on the H-formulation was developed using COMSOL Multiphysics 6.0 to simulate the magnetic interaction between the bulk and the magnet. It was found that the larger sample sizes and multi-bulk arrangements significantly enhanced both levitation and guidance forces compared to a single small bulk. General, the results underscore that, the spatial arrangement and size scaling of HTS bulks play a critical role in maximizing levitation force for superconducting Maglev vehicle and HTS bearing applications. The combined use of experimental and numerical modelling provides a valuable framework for optimizing nextgeneration HTS systems tailored for high-efficiency, high-stability levitation applications.