For A.C. application, supercondcuting strands are boundled and twisted to make a cable with large current capacity. The quench characteristic of such cable depends on the contact thermal and the electrical conductivities between strands, significantly. For improvement of th stability of non-insulated superconducting multi-strand cables, it is neccessary to decrease the local rise of temperature by Joule heating in current redistributon among strands in a quench process. For this purpose, we discussed the influence of Cu allocated to non-insulated NbTi/CuNi superconducting strands. We also prepared some kinds of non-insulated three-strand cables with Cu allocated to the center and the surface of strands. In this paper, the transient stability of these cables is investigated analytically (using 3D Finitie Element Method) and experimentally, and the effect of Cu-sheath on the transient stability is shown. We adopt the relationship between the transport current and the minimum quench energy (MQE) as a stability criterion.
展开▼
