Modeling and Measurement of the Levitation Force in Superconducting Magnetic Bearings with Thinned HTS Tape Stacks

Superconducting Magnetic Bearings (SMBs) have the potential to revolutionize maglev technology by enabling frictionless levitation, higher efficiency, and intrinsic stability. High-temperature superconductor (HTS) tape stacks offer better mechanical properties, better thermal conductivity and greater design flexibility compared to bulks. By reducing the thickness of HTS tapes, a higher engineering critical current density can be achieved, leading to a higher levitation force.
In this study, we reduced the thickness of THEVA HTS tapes by electropolishing the Hastelloy and silver layers, decreasing it by 20% from 61 µm to 49 µm. We measured levitation force hysteresis loops between a stack made of 205 electropolished tapes (10 mm height) and a Halbach permanent magnet (PM) array at zero-field cooling. We compared the results with three 3D numerical methods: the MEMEP 3D method, the Segregated H formulation method, and the volume integral equation method (implemented in C++, COMSOL Multiphysics and Fortran, respectively) [1].
Both experimental and numerical results showed that reducing the thickness of THEVA HTS tapes enhances the maximum levitation force by 14% at 77 K. ... mehrAt about 72 K, the maximum levitation force in the tested PM setup reaches its peak and saturates, whereas a similar stack of non-electropolished THEVA HTS tapes reaches saturation at 54.7 K. The increased levitation force at higher temperatures are particularly attractive for applications due to the reduced cooling effort. These results highlight the advantage of optimized HTS tape stacks for improving SMB performance in maglev applications.