Experimental evidence for an interaction effect in the coupling losses of cabled superconductors

It is experimentally demonstrated on a series of one-stage superconducting cables, composed from multifilamentary superconducting wires, that the coupling current losses being induced in the wire and in the cable matrix, contain interaction loss terms directly proportional to the wire twist pitch I_w. This proves partly their theoretically expected l_c.l_w-dependence. Different twisting directions in a one or multistage superconducting cable increase the ac losses and should be avoided. The magnitude of the effect can become important.