Microstructural Sources of Reduced Residual-Resistance Ratio in Nb[subscript]3Sn Wires

Abstract

Residual resistance ratio (RRR) is a measure of metallic purity. In a superconductor inside a magnet system, impurities degrade the ability of electrical stabilizing materials to safely carry electric current in the event of a magnet quench. The purpose of this study was to analyze the ability of superconductor manufacturers to produce high-RRR niobium-tin (Nb[subscript]3Sn) wires in large batches and over time, as their productions have scaled up to meet current demand. Additionally, microstructural investigation (using SEM/EDS) was performed to determine the reasons for reduced RRR from one manufacturer.