Levitation force approximation of YBCO hybrid superconductors using critical-state theory and partitioning method

Abstract

Introducing the second-generation coated conductor tapes (2G tapes) can enhance the performance of YBCO bulk superconductors (SCs) in terms of force, damping, and shape diversity. In this study, we investigate a hybrid SC that utilizes 2G tapes wrapped around the pivotal bulk component to achieve performance improvements. We also present a straightforward method, based on critical-state theory, to approximate the levitation force of this hybrid SC. This method characterizes the stack of tapes as an equivalent bulk with higher anisotropy and applies a fitting Kim model as an integrated expression of Jc(H) and Jc anisotropy. The partitioning method divides the SC into several isolated elements where the external field is approximately uniform within each sub-volume. Comparisons of calculated results with experiments indicate that this method can predict levitation properties with reasonable accuracy in just a few seconds. Furthermore, we propose two geometries of hybrid SC, namely, width-hybrid, and height-hybrid SC, for practical applications. Among them, the width-hybrid form exhibits higher efficiency in levitation. Our findings highlight the importance of applying the coated conductor stack when the magnetic field orientation is perpendicular to the a-b planes.

Enhancing levitation force of superconductors through wavelength optimization in Halbach permanent magnet arrays

“…In addition to the experiment and FEM simulation, a straightforward method based on critical-state theory [24,25] was used to approximate the levitation force in this system. This approximation utilized a partitioning method that divided the SC into several isolated elements where the external field was approximately uniform within each subvolume (more detailed descriptions can be seen in [26,27]). Within each subvolume, the induced current was calculated based on the critical-state theory and the assumption of a uniform magnetic field [13].…”