Magnetic property observation of high temperature superconducting bulk material by magnetic flux distribution and flux creep measurement

Abstract

Because the high-Tc superconducting bulk material has grains of various sizes, its magnetic properties are not uniform in the material. Therefore it is important for applications using the high-Tc superconductor to develop a nondestructive measurement method in order to evaluate magnetic properties characterization of the superconducting bulk materials. This paper describes measurement methods of macroscopic magnetic property of the high-Tc superconducting bulk material without destroying them. We had developed a magnetic field visualization system, which enables measurement of magnetic field using a Hall device probe and produces visual images of the magnetic field on a computer display. The magnetic flux on the surface of YBCO bulk material was measured by this system under the field of −500 to 500Oe and was visualized into two dimensional graphics. The pattern of the flux distribution was roughly in agreement with the grain morphology. And properties of the superconductor were assessed by measuring of flux creep too. By the experimental results, these methods are useful to assess the property distribution of the superconducting material.