Critical Current and AC Loss Characteristics of Ultrafine Nb3Al and Nb3Sn Superconducting Wires Under Conduction Cooling

Wind and React (W&R) technology is required to produce superconducting magnets using A15 superconducting wire. Recently, the Jelly-roll processed Nb3Al and the bronze processed Nb3Sn ultrafine superconducting wires with a wire diameter of less than 50 mu m were fabricated by the National Institute for Materials Science (NIMS) in Japan. The ultrafine Nb3Al and Nb3Sn superconducting wires will enable the fabrication of superconducting magnets using the React and Wind (R&W) method. In order to apply Nb3Al and Nb3Sn ultrafine wires to DC and AC applications, it is necessary to clarify the temperature dependence of the critical properties and AC loss characteristics of these wires. In this study, the critical properties and AC transport loss characteristics of the developed Nb3Al and Nb3Sn ultrafine wires were experimentally determined using a cryocooler system. The critical temperature (T-c) and critical current density (J(c)) of Nb3Sn wire were higher than those of Nb3Al wire, but the Nb3Al wire showed a higher engineering critical current density (J(e)) than the Nb3Sn wire. The magnitude of AC transport current loss of the Nb3Al wire was smaller than that of the Nb3Sn wire with the same wire diameter.