Improvement of Persistent Magnetic Field Trapping in Bulk Y-Ba-Cu-O Superconductors

Far type II superconductors, magnetic field can be trapped due to persistent internal super-current. Quasi-persistent magnetic fields near 2 Tesla at 60 K (and 1.4 T at 77 K) have been measured in mini-magnets made of proton irradiated melt-textured Y-Ba-Cu-0 (MT-Y123) samples. Using this effect, high field permanent magnets with dipole, quadrupole, or more complicated configurations can be made of existing MT-Y123 material, thus bypassing the need for high temperature superconductor (HTS) wires. A phenomenological current model has been developed to account for the trapped field intensity and profile in HTS samples. This model is also a guide to select directions of materials development to further improve field trapping properties. General properties, such as magnetic field intensities, spatial distributions, stabilities, and temperature dependance of trapped field will be discussed.