AC LOSSES OF A 10 KA NBTI CABLE-IN-CONDUIT SUPERCONDUCTOR FOR SMES APPLICATIONS

In this paper we present a.c. loss investigations performed on a 10 kA prototype cable-in-conduit superconductor with a NbTi basis. The twis ted and braided conductor was under development for a superconducting 180 MJ energy storage model coil with B-max = 5.4 T at I-max = 10 kA. Special aspects of our measurements are the coupling loss dependence o n the Cr coating and on the plastic deformation of the basic multifila ment wires in the cable. Further, we separately determined the individ ual contributions from the different conductor components to the coupl ing losses. Also, the influence of the void fraction in the conductor on the coupling losses was investigated. In addition, d.c. transverse resistance measurements were performed on the cable. The measured hyst eresis and coupling losses are small for such a large current conducto r and were sufficiently low for our purposes. Further a.c. loss reduct ion could be achieved by a proper choice of the basic multifilament wi re in the cable. Our a.c. loss results should also be useful for other pulsed magnetic field applications of this conductor type.