The influence of sample thickness on the trapped field in single-domain REBa2Cu3O7-δ bulk superconductors

Investigating the trapped field (B_tr) of single-domain REBa₂Cu₃O_7-δ (REBCO, RE is Rare Earth Elements) superconducting bulk materials is crucial for enhancing their performance, as well as advancing their practical applications. This study constructs a comprehensive physical model, considering key parameters including the critical current density of superconducting bulks, their diameter and thickness, as well as the observation height. A mathematical model for calculating the trapped field of REBCO bulks has been developed based on the Biot-Savart law and the Finite Element Method, and simulated using Matrix Laboratory (MATLAB) software. In this study, the critical current density of the REBCO bulk superconductor was set to 31,150 A/cm², with a fixed diameter of 20 mm and thickness varying from 2 mm to 40 mm. The trapped field was numerically simulated at a position 0.5 mm above the surface of the bulk superconductor. The results show that the B_tr increases with thickness and saturates when the thickness reaches approximately 30 mm—thickness-to-diameter ratio is approximately 1.5. This study serves as a reference for the preparation of high-quality REBCO bulk superconducting samples and provides novel insights into trapped magnetic field research.