Development of RE123 and MgB2 Superconducting Bulk Magnets

Since the discovery of high temperature superconductors in 1986, superconducting materials come in a variety of forms, not only in wire forms but also in bulk forms [1]. Especially, high temperature superconducting bulk magnets, REBa2Cu3Oy (RE123) and MgB2, generate strong magnetic field in compact size [2-4], since superconducting bulks have high critical current density under up to high magnetic fields. Once bulks are magnetized, magnetic field by the superconducting current is maintained because of strong pinning and bulks work as strong permanent magnets under the cooling condition. In other word, superconducting bulks are regarded as bulk-shape coils which consist of superconducting wires connected with perfect superconducting joints. In this presentation, conditions and outlook of high temperature superconducting bulks, RE123 and MgB2 bulks, are discussed by comparison. Specifically, RE123 and MgB2 bulk magnets were fabricated and, local and global magnetic properties of these bulks were evaluated to investigate the possibility that superconducting bulks have the potential as a powerful magnet [5]. Furthermore, homogeneity of trapped magnetic field in radial and circumferential directions which is very important for equipment design was also evaluated.