MAGNETIC-LEVITATION AND BEAN MODEL

The levitation forces for both free sintered and melt-powder-melt-grow th (MPMG) yttrium-barium-copper-oxide (YBCO) superconductors have been measured by a torsion balance. The results agree with data obtained b y other experimental groups. These levitation forces also have been ca lculated theoretically by taking into account both the Meissner effect and the induced current due to the critical state of the superconduct or. Acceptable agreements are obtained. It is found that the large are a enclosed by the hysteretic levitation curve corresponds to a large c ritical current density of the superconductor.