Transport Property of REBCO Superconducting Joints in Magnetic Fields at Various Temperatures
We are developing a cryocooled (RE)Ba<sub>2</sub>Cu<sub>3</sub>O<sub>7</sub> (REBCO; RE = rare earth) persistent-mode superconducting magnet system that generates 1 T with multiple superconducting joints. In parallel to the design of the system, we have investigated transport characteristics of the REBCO superconducting joints. Critical currents (<italic>I</italic><sub>c</sub>) were measured as a function of magnetic field and temperature. Two joint samples with <italic>I</italic><sub>c</sub> of 107 and 53 A at 77 K, self-field were measured. The first one showed <italic>I</italic><sub>c</sub> of 357 A at 50 K and 0.1 T (magnetic field is perpendicular to the tape surface). <italic>I</italic><sub>c</sub> of the REBCO joint samples showed remarkable hysteresis. The anisotropy of <italic>I</italic><sub>c</sub> changed with temperature. <italic>I</italic><sub>c</sub> at <italic>B</italic> perpendicular to the tape were higher than those at <italic>B</italic> parallel to the tape at temperatures below 20 K. The random pinning is possibly the dominant pinning mechanism in the whole temperatures for the REBCO superconducting joints in magnetic fields perpendicular to <italic>c</italic>-axis.