Effect of sample geometry on levitation force in seeded-melt-grown single-domain YBa/sub 2/Cu/sub 3/O/sub x/

Magnetic levitation force is a key factor that influences energy loss in flywheel energy storage applications. Experiments on the relationships between levitation force and YB/sub 2/Cu/sub 3/O/sub x/ sample geometry have been conducted. The levitation force has been conducted. The levitation force has been measured for single-domain YBa/sub 2/Cu/sub 3/O/sub x/ samples with different thicknesses and diameters. It has been found that the thickness dependence agrees well with a current model. However, the measured levitation force that was found only within the linear regime. The levitation force in fact increases as the diameter decreases until a threshold value is reached. As the diameter of HTS sample is reduced smaller than the testing magnet (d=12 mm) the force experiences a rather rapid fall. This behaviour can be qualitatively described by a magnetic dipole model based on Meissner currents. Other factors that dominate levitation force are also discussed.