Investigation of the Flux Flow-inhibiting Effect of a Hole-opened Superconducting Bulk Magnet

A hole-opened bulk material has been proposed to supply magnetic flux into the large-size and high-performance bulk efficiently because superconductivity is intentionally lowered in the portion with holes. We were anxious about the flux flow in a high applied field, while it was confirmed that the flux flow was suppressed in a high applied field at a low temperature. To examine the flux flow-inhibiting effect in detail, in this paper, the time response of flux density in four portions, between the holes, the inside of the inner holes, the side opposite the holes, and the center, was measured. Although small holes served as a channel and magnetic flux flew out through a channel just after applying a pulsed field, a channel closed for up to 0.2 seconds, flux flow was disturbed, and then the magnetic flux was trapped. As Jc increased with a decrease in temperature, a channel closed more quickly, and a trapped field was enhanced.