Preferential Magnetic Flux Invasion and Heat Generation Owing to Macrostructure in HTS Bulk Magnets in Pulse Field Magnetization Processes

In order to clarify the behavior of the magnetic flux that invade into the melt-processed Dy123-based high-temperature superconducting bulk magnet, the motions of magnetic fluxes and the phenomena of heat generation were precisely measured during the pulsed field magnetization processes. In the experiments, we estimated the time evolutional profiles that were measured at two portions in the growth sector region and the growth sector boundary. They are characterized as the areas of lower and higher critical current densities than each other, respectively. The serial pulsed magnetic fields of 5 T were applied to the sample at 30 K, and the data were obtained in turn by the Hall sensor and thermometer that were put at several positions along the radial rows on the growth sector boundary and the growth sector region. The profiles of magnetic flux during the pulsed field application actually proved that the magnetic flux invades the sample through the growth sector regions in shorter time and with stronger magnitude than through the growth sector boundaries. Since the low magnetic field application leads to low heat generation, it is expected to achieve the higher trapped field performances than ever.