Development of high‐J_c NbTi multifilamentary superconducting wire with Nb artificial pins for AC applications

Abstract

SUMMARYHigh critical current densities of 1.61 x 10" Aim' at 1 T, 6.1 x lo9 A/mZ at 3 T and 2.9 x lo9 A/m2 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 Ti100 kVA ac superconducting magnet was designed and made by using high J, wire with controlled 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.

Measurement of AC transport current loss in different kinds of superconducting tapes and wires in liquid helium

“…Among them, low-temperature superconductors (LTS) dominate in fusion reactor superconducting magnets [1]. For use in AC devices, NbTi multifilamentary wire with submicron filaments was developed [2] but high-temperature superconductors (HTS) are the other candidates for such applications and these materials represent a new possibility for high-performance fusion reactors [3]. For the successful design of equipment for the alternating current (AC) regime, the understanding of the AC loss is necessary.…”