Patent ID: 7718898

Claim:
A precursor for manufacturing a Nb 3 Sn superconducting wire by an internal Sn process, the precursor comprising: a multi-element wire having a center portion including a plurality of mono-element wires; each of said plurality of mono-element wires having a Cu or Cu-based alloy matrix into which an Sn or Sn-based alloy core is embedded, and having a plurality of Nb or Nb-based alloy filaments surrounding the Sn or Sn-based alloy core, said plurality of Nb or Nb-based alloy filaments configured to have an average distance from the outer diameter of the Sn or Sn-based alloy core of 100 μm or less; and at least one of said plurality of Nb or Nb-based alloy filaments configured to have a distance from the outer diameter of the Sn or Sn-based alloy core of 50 μm or less; and said plurality of Nb or Nb-based alloy filaments having an average diameter of 5 μm to 30 μm, and a diffusion barrier layer surrounding said plurality of Nb or Nb-based alloy filaments; and a stabilizing copper layer surrounding each of said mono-element wires.