Thermal behavior and field-trapping property of melt-textured superconducting bulk magnets activated by quasi-static magnetic fields

The thermal and field trapping behaviors of melt-processed RE-Ba-Cu-O (RE=Y, Sm) bulk superconductors during their magnetization processes conducted in the zero field cooling (ZFC) were investigated in comparison with the field cooling (FC) operations in the temperature range around 50 K. The temperature changes were precisely measured by five thermocouples attached on the sample surface. The authors discuss the relationship between the heat generation and resultant trapped magnetic field ability by means of the direct temperature measurement during these magnetizing processes. As the applied field is not satisfactorily given to the sample, the trapped field distributions activated in ZFC process show trapezoid shapes, whereas they show a corn shape without any strain when magnetized in FC process. The trapped magnetic field gradually increases even after when the applied magnetic fields reaches the highest value. According to the balance on the heat generation and drain, the temperature evolution shows us an almost stable state. These data suggest that the improvement with respect to the heat propagation of the bulk material must suppress the temperature rises and enhance the resultant flux trapping ability.