Domain-orientation dependence of levitation force has been determined for single-domain YBa2Cu3Ox. The single-domain material is obtained from a seeded melt growth process. The levitation force has been found to reach a maximum as the c axis of the domain is parallel to the direction of the force. The levitation force decreases in a cosine law fashion as the angle θ (the angle between the direction of the force and the c axis) increases from 0° to 60°. A maximum anisotropy of levitation force of 2.29 has been found. A physical model is proposed to explain the observed orientation dependence.

No abstract

Using a seeded melt growth (SMG) method, we have produced single-domain YBa2Cu3Ox with high levitation forces and trapped magnetic fields. A threshold temperature TL has been found above which extraneous nucleation does not occur. Surface nucleation has been suppressed when the top sample surface is coated with low melting compounds. The planar growth rates along the a- and c-axes have been found to be comparable within the undercooling range used in this study, and agree well with the current model. Major factors that strongly influence the levitation force have been studied in detail including domain geometry and orientation. Current physical models have been used to interpret the observed levitation force behaviors.

Magnetic levitation force is a key factor that influences energy loss in flywheel energy storage applications.Experiments on the relationships b e t w e e n l e v i t a t i o n f o r c e a n d Y B 2 C u 3 0 , sample geometry have been conducted. The levitation force has been measured for singled o m a i n Y B a 2 C U 3 0 samples with different thicknesses and diameters.It has been found that the thickness dependence agrees quite well with a current model. However, the measured levitation force 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 behavior can be qualitatively describled by a magnetic dipole model based on Meissner currents. Other factors that dominate levitation force are also discussed.

No abstract