YBCO Superconducting Coils Operated at Nitrogen Temperature

Abstract

Trial coils of YBa₂Cu₃O _x superconductor were prepared from oxide superconducting powder and binder mixtures. The critical temperature of the wire was more than 86 K in the four-probe measurement. Magnetic fields, 21.1 gauss, and 350 gauss were generated by dc operations at 77 K and 4.2 K, respectively. A critical current density in the coil was of 1,330 A/cm², corresponding to a level of 77 K and zero magnetic field. Experimental results show that an oxide superconducting magnet with an appropriate protection circuit is feasible and stable at liquid nitrogen temperature.