HIGH-TEMPERATURE SUPERCONDUCTING QUASI-PERMANENT MAGNETS AND THEIR APPLICATION TO SUPERCONDUCTING MOTOR

We succeeded in obtaining Y-Ba-Cu-O superconducting bulk magnets (abbr eviated as Supermagnets) which can trap the magnetic fields exceeding those of ordinary permanent magnets. The flux motion during the pulsed field magnetization (PFM) was evaluated at 77 K. The flux penetration into the sample is sluggish when the field is low, but it suddenly pe netrates when the external field exceeds 1.5 T. The PFM technique was applied at temperatures below 77 K to magnetize Supermagnets. The high est flux density of 2.1 T was achieved at the surface of the sample wh en magnetized by PFM at 30 K by using a cryocooler. A superconducting motor was constructed for the first time in the world by using Superma gnets as field magnets. The motor performances at 77 K and 65 K reache d the values of 2 kW and 3.5 kW, respectively. We have technically est ablished that Supermagnets can be used in Various practical applicatio ns.