AC magnetic shielding characteristic of a YBCO superconductor using magnetic field visualization measurement

The magnetic shielding is used as one of applications of the high- T c superconductor (HTS). Magnetic characteristics of the HTS are not uniform, since it has grain boundaries and cracks (weak links). Thus, the evaluation of the magnetic flux invasion by the flux flow into the HTS is important. In this research, magnetic characteristics of the HTS on AC magnetic field from 1 to 250∼Hz were evaluated. From these experiments, we were able to understand that the polycrystal HTS had high magnetic shielding performance at the higher frequency, even if it contains a lot of weak links.