Development of Single-Stacked Internal-Tin Nb $_{3}$ Sn Superconducting Wire

The internal-tin technique is an excellent method of fabricating Nb 3 Sn superconducting wires with high critical current densities. We have developed an internal-tin Nb 3 Sn wire in which the multi-filamentary wire is fabricated by assembling mono-filamentary Nb elements and mono-filamentary Sn elements. The simple fabrication process allows a reduction in the fabrication cost of the wires. By optimizing the spacing of the Nb 3 Sn filaments, a 600 m long wire with a high critical current density of 400 A/mm 2 at 18 T and no flux jumping was fabricated.