Electromechanical Modeling of Nb₃Sn Superconducting Wires Subjected to Periodic Bending Strain

The transport performance of Nb₃Sn cable-in-conduit conductors (CICCs) depends on the strain distribution along the superconducting filaments determined by the combination of electromagnetic and mechanical forces applied to the strands. Experimental studies on the effect of bending strain were performed at the University of Twente by means of the Test Arrangement for Strain Influence on Strands (TARSIS) facility. The aim of this paper is to verify the agreement between a detailed electromechanical model of the wire and the experimental results obtained in TARSIS. A numerical model of two Nb₃Sn internal tin strands was developed, which describes the wire through a distributed parameter nonlinear electrical circuit. The model requires a single strand to be discretized into a number of elements, connected by transverse conductances and subjected to a given strain distribution. The strain distribution maps were computed at the École Centrale Paris by means of the MULTIFIL code at different experimental conditions in the TARSIS facility. The simulation results show good agreement with the experimental ones in terms of both critical current and n-value degradation.