Examination of Optimized Pulsed Field Magnetization for a YBCO Bulk Superconductor

Abstract

Bulk-type YBCO superconductors prepared by the MPMG process exhibit the high critical current density Jc, and are promising for many practical applications such as magnetic levitation. A magnetic levitation system is to use as a strong superconducting bulk magnet by magnetizing the high-Tc superconductor (HTSC). When superconducting bulk magnets are activated using the field cooling procedure under a DC magnetic field, a large electromagnet system or a superconducting coil is needed. In contrast, a pulsed magnetic field using a small coil is applied a strong magnetic field for magnetizing the HTSC. Therefore, it is important to evaluate the pulsed field magnetization properties of the HTSC. Since superconducting properties are not homogeneous in some specimens due to grain boundaries and cracks, spatial distribution of magnetization properties should be assessed. In the present research, the distribution of the pulsed field magnetization was measured with a magnetic field visualization system.
The magnetization with the pulsed magnetic field is done in the state of the zero field cooling. However, it is necessary for enough magnetization of the HTSC to consider the time constant on the magnetic flux invasion and the flux flow, when the applied magnetic field decreases. Therefore, we examined the optimum pulsed magnetization for the HTSC. The optimum value of the pulsed magnetization existed.