Magnetic Screening Behavior of Hybrid High-Temperature Superconducting Screens Subjected to Successive Excitation Cycles: Experiments and Numerical Study

Combining high-temperature superconducting bulks and jointless closed-loop coated conductors recently demonstrated promising magnetic shielding/screening properties when they are zero-field cooled and subjected to an inhomogeneous applied field. The present work focuses on studying how their screening properties evolve if several magnetic field excitation cycles are applied, as it is the case in practical applications. This study is carried out both experimentally and numerically. The main result is that more than 95% of the field attenuation (screening factor SF) obtained after the first ramp still remain after 300 cycles. This result is explained by using the numerically computed current density distribution in the bulk alone. The slight decrease in SF after several cycles is found to be smaller than the field attenuation arising from conventional current re laxation (or flux creep) if the magnetic field is kept constant after the first increasing ramp. These results demonstrate the potential of such superconducting screens for practical applications with a large number of excitation applied field cycles.