Measurement of the Transversal Resistivity in Superconducting Strands With a 4-Probe Technique

In multi-filamentary superconducting strands the transverse resistivity gives a fundamental contribution to the mechanisms governing the coupling losses in AC regime and the current transfer length, for example influencing the performance of wires with bending strain. Nevertheless, the transverse resistance matrix generally used into the simulation codes of superconducting strands is determined as a fitting parameter obtained from the experimental V-I curves. The first direct measurement of the transverse resistance as a function of the temperature in multi-filamentary wires by using a 4-probe method has been performed at ENEA. Here we study the effect of a background magnetic field on the V-I characteristics, obtaining interesting results. Moreover, the resistivity between the bundles and the outer copper layer is measured at different temperatures. These experimental values, together with the inter-bundle resistivity, are inserted as input parameters in the strand current diffusion equations, for the validation of a finite differences numerical model. The agreement between simulated V-I curves and experimental characteristics is excellent.