Correlation Between Density and Levitation Performance of YBCO Bulk Superconductor Over Halbach NdFeB Guideway

The loading capacityand stability of the high temperature superconducting (HTS) maglev system greatly depend on the levitation performance of bulk superconductor. Because of the differences in size and fabricating process of the bulks, there was no unified standard and simple method to evaluate the difference in levitation performance among bulks. In this work, we measured the density of 19 YBaCuO (YBCO) bulk samples in different shapes and sizes while their zero-field cooling levitation force and relaxation over a Halbach NdFeB guideway were studied. The results show a significant correlation between the density and levitation performance of a single YBCO bulk superconductor. For samples with the uniform fabrication process and similar properties, higher density means larger levitation force per unit area and smaller relaxation ratio. This conclusion could serve as a reference for HTS Maglev researchers and engineers quickly selecting YBCO bulk superconductors.