Critical current properties in magnetic fields of YBCO superconducting rods prepared by unidirectional solidification method

Abstract

We fabricated long length YBCO single domain superconducting rods of 150 mm in length by the unidirectional solidification method. From the observation of microstructures of the rod, it was confirmed that the volume fraction and size of Y211 phase crystals tend to increase with progress of unidirectional solidification. These phenomena could be explained by the pushing mechanism of the Y211 particles into the liquid phase by the growth interface and coarsening of Y211 particles in the liquid region. We have also confirmed the change of J c– B properties at the difference of the volume fraction and the morphology of Y211 phase crystals along the longitudinal direction. Using the middle regions of this YBCO rod, where the J c– B property is superior, we have fabricated the current leads supported with epoxy resin and FRP. We have obtained the critical current about 380 A at 77 K and 3 T where the ab-plane is in parallel to the applied magnetic fields. Additionally, we have also successfully supplied 1000 A current at 77 K and 3 T connecting the three current leads in parallel.