Resistivity Ratio of Niobium Superconducting Cavities

TL;DR

This paper presents resistivity measurements of niobium, lead, and copper at various temperatures using a contactless method, providing insights into material properties relevant for superconducting cavities.

Contribution

It introduces a simple contactless measurement technique for evaluating resistivity and related superconducting parameters of materials used in cavities.

Findings

Resistivity varies with temperature and material.

Method allows estimation of critical magnetic fields.

Material parameters like mean free path are monitored.

Abstract

Resistivity measurements have been made on Nb cavities, as well as on Pb and Cu, at 296, 77, and 4.2 K by means of a contactless induced-current method. For superconductors, a constant magnetic field drives the material normal below the transition temperature. These measurements provide a simple means for initial material evaluation as well as a direct means of monitoring the effects of material parameters (purity, heat treatment, gas incorporation, etc.) on the electron mean free path. Approximate determinations of Hc, Hc1, and Hc2 can also be derived from these measurements. Normal-state thermal conductivity and the Ginzburg-Landau parameter kappa are calculated from the resistivity measurements.