Resistivity and RRR Measurements on Grooved SMES Aluminum Stabilizer Bar by the Eddy Current Decay Method

Abstract

Measurements are reported of resistivity at room temperature, 77K, and 4.2K on one inch diameter longitudinally grooved bars of pure aluminum. The application is superconducting magnetic energy storage (SMES) where long lengths of the superconductor stabilizer component must be qualified to a residual resistivity ratio (RRR) specification. The measurements are taken by the Eddy Current Decay (ECD) method and compared to similar measurements on ungrooved bars of the same material. Experimental results show that there exists a fixed ratio between time constants for the grooved and ungrooved bars. The ratio for the standard SMES aluminum stabilizer bar is about 0.45. It is expected that for large numbers of samples and measurements, significant savings will be realized using the ECD method as opposed to the conventional current transport method for RRR characterization.