Temperature Changes and Magnetic Properties of Melt-textured Superconducting Bulk Magnets in the Magnetizing Processes using Quasi-static Magnetic Fields

Abstract

The temperature changes and magnetic-field trapping behaviors of melt-textured, single-domain Sm-Ba-Cu-O bulk superconductors have been precisely investigated for magnetizing processes by means of quasi-static magnetic fields such as field cooling (FC) and zero field cooling (ZFC). The experiments were conducted in the temperature range of 40-80 K by simultaneously measuring both the temperature and magnetic flux density. According to the balance of heat generation and drainage, the temperature evolution profiles show distinctive behaviors of the invading and exhausting magnetic fluxes into and out of the HTS bulk magnet. The average temperature change during the FC process reached the maximum value of 4.63 K when the sweep rate was 11.3 mT/s and the initial temperature was 45.6 K. In the ZFC process, both the temperature and magnetic flux density kept increasing gradually even after the external magnetic field stopped growing at 5 T in the ascending field process. The highest temperature rise due to the flux motion reached 4.6 K even when the sample was magnetized with at sweeping rate of 11.3 mT/s. As the behavior of temperature rise was different between the ascending and descending field processes, it is suggested that the magnetic fluxes in the processes invade and diffuse under different heating characteristics.