We have been studying about the superconductig wires for AC use by Powder-Metallugy Process. Nb and Cu-1%Mn powders preparedby PREP (Plasma Rotating Electrode Process) were used, because the PREP powder is not contaminated by oxigen and has good workability. The starting material is the mixture of Nb and Cu-1%Mn powders, and the ratio of mixteure is (Cu-1%Mn)-15 to 50%Nb. We measured and estimated the critical current densities and the hysteresis losses of the wires.
The critical current densities are propotional to the Nb concentration powered by 2. As the Nb concentration is increased, the effective filament diameters and upper critical magnetic field increase.
As the superconducting fiaments are discontinuous in the powder-metallugy processed wires, the critical current density depends on the frequency of bridging among superconducting filaments. Moreover the filaments'bridging causese the increase of the effective filament diameters.