A new class of AC superconducting conductors

Superconducting wires for 50-60-Hz applications must have very small diameters to obtain intrinsic stability and low AC losses. Concepts for the latest GEC ALSTHOM conductors that give them particular quench properties, leading to self-protection against burning or breakdown, are presented. C-type wires are industrial products with a typical diameter of 0.5 mm, presenting intrinsic performance similar to those of classically optimized wires of 0.2-mm diameter. C-type wires can be used as basic elements of larger assembled conductors. Many configurations are possible. As a first step, cables of six C-wires around one resistive insulated central wire have been realized and tested. The central wire is defined to permit rapid quench detection and a rapid phenomenon of mass quench. The mass quench transforms any possible local quench into a complete quench of the coil, after some delay which is also exploited for passive protection. Experimental results are presented.< >