Effect Of Narrowing The 2G HTS Wires On Electrical Characteristics

In practical superconducting electric power equipment,wires must experience external magnetic field which would reduce its performance including critical current,AC loss and so on,especially when it is perpendicular to the wire's surface.In order to reduce influence of the external magnetic field,the main idea is applying twist or transposing structure which is effective for low temperature superconducting wires.However,with limitations of material properties,the second generation(2G)high temperature superconducting(HTS)wires are entirely based on 4 mm or over 4 mm width,method above is hard to apply.In this study,a type of narrow wire within 2 mm width is proposed for further improving the electrical characteristic of HTS wires.Manufacture process of narrow wires is mastered on condition that little critical current degradation is brought during narrowing process.First,critical current distribution of long narrow wires are tested to verify the critical current uniformity of narrowing process.Next,narrow wire samples with different structures are prepared,and their critical current and AC loss characteristics are measured and analyzed.The results show that V-I curves for the narrow wires with stack or twist structure are the ones of typical superconducting wires.Thus feasibility of the narrow wires is confirmed from the critical current point of view.AC losses of single narrow wires measured in experiment are in good agreement with theoretical values from the Norris model,as well as with numerical calculated results.Measured AC losses of the stack structure wires are sandwiched between theoretical values from the elliptical and thin strip equations of the Norris model.