Manipulation of Screening Currents in an (re)ba2cu3o7−x Superconducting Magnet

Rare earth (RE) Ba2Cu3O7−x (REBCO) magnets are known to have the inherent problem of field inhomogeneity due to the screening current induced field (SCF). To mitigate SCF, multiple approaches have been introduced, most of which are based on electromagnetic manipulation of screening currents induced in the REBCO layers of a magnet. Precise estimation of spatial distribution and temporal behavior of SCF in a ‘magnet’ level is challenging because it requires substantial computation time to simulate time-varying screening currents in all individual turns of a magnet. This paper presents numerical and experimental results of manipulation of SCF in an actual REBCO magnet that consists of a stack of 13 double pancake coils. For faster and more effective simulation, the ‘domain homogenization’ scheme together with the ‘2D edge-element magnetic field formulation’ was employed to consider the net transport current constraint of each turn. Spatial and temporal behaviors of SCF were investigated in various overshoot-current operations, where an optimal overshoot charging sequence could be determined to negate SCF at the magnet center. Simulation results agreed well with experimental ones, which validates the proposed approach to mitigate SCF in a magnet level.