Switching characteristics of MgB2 wires subjected to transient application of magnetic field

We investigated current transport properties in MgB2 wires subjected to transient application of magnetic field, and then discussed their applicability to magnetically controlled switching elements. These wires were fabricated by powder-in-tube (PIT) technique, and Cu-Ni as well as stainless was utilized for their sheath material. A short sample of the wire was installed in a Gifford-McMahon (GM) cryocooler, and was impregnated with solid nitrogen for the sake of thermal stabilization. After stabilizing the temperature of the sample at a certain bias current, the voltage and the temperature in between potential taps were monitored with a transient application of magnetic field. Such measurements were repeated systematically as functions of bias current, operating temperature and magnetic field intensity. It was shown that the sample quickly generated resistance without temperature increment by applying the transient and weak magnetic field. This indicates the applicability of MgB2 wires to persistent current switches (PCS) with quick response.