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

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.