Forces acting on Y-Ba-Cu-O superconductors in a magnetic field at 77K.

Repulsive forces by the Meissner effect act on Y-Ba-Cu-O superconductors (polycrystalline superconducting oxides) at 77K in a magnetic field.The forces are measured experimentally in the cases of bulk and thin strip superconductors.Also, the forces are calculated by the numerical method under the assumption that the superconductor is a perfect diamagnetic body.Compairson between the both values in the bulk superconductor reveals that the experimental values have a range from 20 to 40% of the calculated values because the magnetic fluxes penetrate the superconductor even below the lower critical magnetic field.It is proposed that the real forces produced by the Meissner effect of the Y-Ba-Cu-O superconductors are estimated using the magnetic susceptibility of the superconductors, Although the estimated values using the proposed method are not good approximate values of the real forces in the thin strip superconductors, it is found that the method is valid for the bulk superconductor.1.