Fracture Statistics of Individual Nb[subscript]3Sn Filaments

Abstract

Superconductors are a class of material that, when cooled to low temperatures, conduct electricity with zero resistance. The main use of superconductors is in large magnet systems for particle accelerators and the ITER experimental fusion reactor being built in France. Nb[subscript]3Sn, processed into composite, multifilamentary wires, is one of the main superconducting materials used in these magnet systems. Due to Lorentz forces induced during magnet operation, the brittle Nb[subscript]3Sn filaments in these wires crack, causing a degradation of the performance of the magnets. Previous experiments probing the fracture mechanics of Nb[subscript]3Sn filaments have utilized whole wires in their tests. The purpose of this study was to extract the tiny Nb[subscript]3Sn filaments from their component wires for testing, and therefore, probe the intrinsic properties of Nb[subscript]3Sn.