Levitation force of melt-textured YBCO superconductors under non-quasi-static situation

Highlights: • Two YBCO samples with different performance originated from the residual carbon content in precursor powders before crystal growth are used to investigate superconducting levitation force under non quasi-static situation. The relative speed value between superconductor and magnet is much higher than conventional studies. • Crossing phenomena can be both experimentally observed in the force–displacement hysteresis curves of superconductor with high and very low critical current density. • The experimental results reflect the vortex motion under dynamic condition. Crossing is tightly related to time-variation characteristics of trapped magnetic field and flux creep in a superconductor, which should be taken into consideration for the development of superconducting levitation system. - Abstract: The superconducting levitation force of a simple superconductor-magnet system under non-quasi-static situation is investigated experimentally. Two yttrium barium copper oxide (YBCO) samples with different performances are chosen from two small batches of samples prepared by the top-seeded melt-textured growth process. The residual carbon content of the precursor powders of the two batches is different due to different heat treatment processes. During the experimental process for measuring the levitation force, the value of the relative speed between the YBCO sample and the permanent magnet is higher than that in conventional studies. The variation characteristics of the superconducting levitation force are analyzed and a crossing phenomenon in the force–displacement hysteresis curves is observed. The results indicate that the superconducting levitation force is different due to the different residual carbon contents. As residual carbon contents reduce, the crossing phenomenon is more obvious accordingly.