Analyses of Deformation Due to Screening-Current-Induced Force in Layer-Wound REBCO Insert Coil for 1.3-GHz LTS/HTS NMR

REBCO wires have high critical current density and thermal stability, and are being applied in various fields such as NMR, MRI, and accelerators. We are currently designing a 1.3-GHz LTS/HTS NMR magnet that operates in a persistent current (PC) mode. However, there are issues with using REBCO coils that need to be resolved. One problem unique to REBCO coils is non-uniform electromagnetic forces caused by screening currents. During the charging and discharging of the coil, screening currents are induced, resulting in a significantly non-uniform current distribution within the coil. As a result, non-uniform electromagnetic forces are generated within the coil due to these screening currents. In this study, we performed an electromagnetic stress analysis using a two-dimensional axisymmetric structural analysis that considered tension during winding, thermal stress during cooling, and electromagnetic force during charging. First, we compared the results of the numerical simulation of the layer-wound REBCO coil with the experimental results. Then, we conducted numerical simulations of an insert REBCO coil in a design example of a 1.3-GHz NMR to evaluate the stress and deformation of the REBCO coil.

Automated summary

REBCO wires with high critical current density and thermal stability find applications in various fields such as NMR, MRI, and accelerators. We are currently designing a 1.3-GHz LTS/HTS NMR magnet that operates in a persistent current mode. However, there are issues with using REBCO coils, particularly the non-uniform electromagnetic forces caused by screening currents.