  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.

Superconductivity;Materials Science