Stabilizing superconductors for power engineering applications

Exhibiting essentially zero resistivity at high current densities and large magnetic fields, modern superconducting materials offer intriguing possibilities in power engineering. However, in order to utilize this property in any large scale application, the superconductor must be stable during fault and overload transients in the total system. In order to know whether the superconductor itself is stable, one must understand and control the detailed mechanisms of magnetic flux motion which occur in the material. Such flux motion will give rise to a non-zero resistivity and hence will always involve heat generation, which in turn will perturb the low temperature environment necessary to sustain superconductivity. This paper discusses the essential differences between superconductors and ordinary conductors; the control of heat generation resulting from magnetic flux motion necessary to insure that the superconductor is stable; and some experiments on models of dc superconducting transmission cables which test the theoretical assumptions.