A new apparatus for measuring the critical currents of hard type-II superconductive wires and tapes in high fields as a function of temperature throughout their superconducting phase

Abstract

Describes an update of a earlier apparatus which measures the critical current of superconducting wires and tapes as a function of magnetic field and temperature. The critical element is a compact probe of 25 mm diameter which can be inserted into the bore of one of the several high-field magnets. The design and critical features of the probe which incorporates high-resolution thermometry and accurate temperature control in the demanding environment of high sample currents and large magnetic fields, are discussed. Data obtained on a sample of multifilamentary V3Ga wireare presented as an illustration of the probe's capabilities. Analytical modelling and consistency measurements suggest that the accuracy in the critical current data presented can be given by an uncertainty in temperature of +or-0.2 K for 4.2 K<T<or=Tc and +or-0.05 K for T<or=4.2 K.