Measurement of the Two-Dimensional Surface Flux Density Distribution of YBCO Melt-Processed Superconducting Bulk in Steady-State AC Magnetic Field

Abstract

This paper describes the novel scheme of the two-dimensional measurement of the surface magnetic flux density distribution of YBCO melt-processed bulk superconductor exposed in the alternatively changing field. It is well known that the surface flux density distribution is quite important to estimate the current density distribution inside the bulk and the position of the defect. Two-dimensional static field measurements are common and standard in these days, and one-dimensional dynamic ones are reported by many research groups. We tried to measure the two-dimensional dynamic distributions to obtain the further information on the superconducting bulk. The measurement system consists of ten Hall sensors located on straight line, which can be moved toward the perpendicular direction all together. The alternative magnetic field is applied by the external coil, and the sensors are moved in a way synchronized with the field. As the results, we obtain the two-dimensional dynamic surface flux density distribution of YBCO bulk. The specimen has several cracks on the surface, and we are able to find that some of them correspond to the irregular distribution of the results.