Effect of perimeters of induced shielding current loops on levitation force in melt grown single-domain YBa2Cu3O7−x bulk

Abstract

Effects of perimeters of induced shielding current loops (ISCL) on a levitation force have been investigated for a single-domain YBa2Cu3O7−x sample. The sample was prepared by a top-seeded melt–growth process. The levitation force of the sample decreases monotonously with the increasing perimeters of ISCL while the depth of the cutting slot increases along its diameter from one side to another. The maximum levitation force of the sample without any cutting slot is about 1.68 times higher than that of the sample bisected. A simple physical model is afforded to interpret the experimental results.

The homogeneity of levitation force in single domain YBCO bulk

“…The pores which can be seen by eye or low resolution optical micrograph are another cause resulting in low levitation force in the bottom, this can be interpreted by the above model, although the reasons that produce pores are not yet clear. Therefore, according to our model, the effect of the asymmetry diameter of Y211 particles in the bottom on the levitation forces is quite different from that they decrease the critical current, which decreases the effective radius of ISCL, but increases the perimeters of ISCL, and thus this corresponds to a decrease in the grain size, and results in greatly reducing the levitation force in the bottom of the bulk [17]. Using the same idea, the levitation force may be further enhanced by eliminating microcracks and pores in order to improve the density of the bulk in the bottom.…”

“…According to the formula (2), the levitation force F is proportional to the radius of induced shielding current loops (ISCL), and inversely proportional to the perimeters of ISCL [17]. The microcrack in this experiment decreases the effective radius of ISCL, but increases the perimeters of ISCL, this corresponds to a decrease in the grain size.…”

“…where q min is the minimum length of ISCL in the single-domain samples without any crack or damage, q total is the total length of ISCL of the same sample with cracks or damages, and F 0 is the maximum levitation force of single-domain superconducting sample corresponding to q min (experimental data) [17]. According to the formula (2), the levitation force F is proportional to the radius of induced shielding current loops (ISCL), and inversely proportional to the perimeters of ISCL [17].…”

Effect of Cooling Time on the Morphology and Levitation Force of Single‐Domain Gd–Ba–Cu–O Bulk Superconductors by the Infiltration and Growth Technique

“…The levitation forces of the samples were measured under a zero‐field cooling state at 77 K using a self‐made device 26,27 . A magnet (∅30 mm) with a surface field of 0.5 T was used in the levitation force measurements.…”

“…The levitation forces of the samples were measured under a zero-field cooling state at 77 K using a self-made device. 26,27 A magnet (+30 mm) with a surface field of 0.5 T was used in the levitation force measurements. The maximum levitation force measured in this experiment was achieved at the smallest gap (0.1 mm) between the two nearest surfaces of the sample and the magnet.…”