Current distribution in a spiral-pitch adjusted high-Tc superconducting cable

For AC loss reduction on multi-layer superconducting cables, it is important to balance the current sharing ratio among layers by adjusting spiral pitch angles of wires. The effects of this technique were analyzed by using a conventional theoretical approach and a newly developed numerical approach. In the numerical analysis, three-dimensional FEM algorithm was modified to treat nonlinear superconducting properties, and complicated spiral pitch condition was simulated by introducing anisotropy on the conductivity of each layer's conductor. This numerical analysis made it possible to visually observe electromagnetic properties and current distribution within each superconducting layer. This analysis revealed that the theoretical approach without taking the superconducting properties into account does not provide an accurate solution of spiral pitch for balanced current sharing among layers. This result supports the importance of this kind of numerical approach for the analysis of superconductors.