Non-uniform critical current and stacking effect remedy for multi-filament REBCO tapes with potential defects

Abstract

The high aspect ratio of REBCO tapes has a significant impact on several characteristics in high-temperature superconducting (HTS) applications, like critical current and AC loss. Narrow filamentary technology can effectively reduce the impact of magnetic field dependence and enhance the electromagnetic performance of REBCO tapes. However, the existing methods are constrained by the trade-off between the narrow degree of REBCO filaments and high current capacity. Meanwhile, when processing REBCO tapes for large-scale magnets, there is a great possibility that local defects are lurking. A striated narrow-stacked structure is proposed based on the existing narrowing methods to address these challenges. To verify the validity of this structure, it is imperative to explore the non-uniform critical current and stacking effect on performance for multi-filament REBCO tapes with potential defects. This article introduces a magnetic extended network (MEN) model to analyze the electrical characteristics of striated narrow-stacked structures with different types of potential defects. Then, by coupling with a 3-D finite element method (FEM) electromagnetic module, the calculation results of the MEN model are visualized and used to analyze the electromagnetic characteristics including current sharing mechanism, magnetic field distribution, and critical current compensation due to stacking effect. It is found that stack structures successfully provide the performance remedy for multi-filament REBCO tapes with potential defects. This study aims to promote the narrowing improvement of REBCO tapes in high-field magnets and high-current applications.