Development of high-J(c) NbTi multifilamentary superconducting wire with Nb artificial pins for ac applications

High critical current densities of 1.61 x 10(10) A/m(2) at 1 T, 6.1 x 10(9) A/m(2) at 3 T and 2.9 x 10(9) A/m(2) at 5 T were achieved by controlling the distribution of Nb artificial pins in NbTi multifilamentary superconducting wires for ac applications. The critical current densities attained are over two times higher than those of conventional ac superconducting wires. This increase can be attributed to the shift of the peak of pinning force density to higher magnetic field by optimizing the pinning parameters. The benefits of increasing critical current densities for ac applications are demonstrated. A 2.5 T/100 kVA ac superconducting magnet was designed and made by using high Je wire with controled distribution of Nb artificial pins. Compared with conventional ac superconducting magnets, the new magnet exhibits a drastic decrease in size as well as in ac losses.