Screening current effect on the stress and strain distribution in REBCO high-field magnets: experimental verification and numerical analysis

TL;DR

This study investigates how the shielding effect influences strain distribution in REBCO high-field magnets, combining experimental measurements with numerical modeling to understand and mitigate screening-current-induced magnetic fields.

Contribution

The paper provides experimental verification and numerical analysis of the shielding effect on strain distribution in REBCO coils, introducing an analytical expression for maximum radial Lorentz force.

Findings

Good agreement between experimental data and numerical models

Proposed analytical expression for maximum radial Lorentz force

Assessment of methods to reduce screening-current-induced magnetic fields

Abstract

Besides screening-current-induced magnetic fields (SCIF), the shielding effect in high-Tc coated conductors also has an strong influence on its strain distribution in a coil winding, especially during high-field operations. To demonstrate this phenomenon, a special experimental setup was designed. With an LTS background magnet and a small HTS insert coil, we were able to carry out direct observations on the hoop strains of a 10-mm wide REBCO sample. Measured data was compared against numerical solutions solved by electromagnetic models based on T -A formulation and homogeneous mechanical models, showing good agreements. An analytical expression was proposed to estimate the maximum radial Lorentz force considering shielding effect. Using the developed numerical models, we further studied the potential effects of two of the mostly investigated methods, which were formerly introduced to reduce SCIF, including multi-filamentary conductors and current sweep reversal (CSR) approach.