Electrothermal Analysis of a Twisted Stacked YBCO Cable-in-Conduit Conductor

A YBCO cable-in-conduit conductor (CICC) for high field magnet applications as well as for energy transmission is under development at the ENEA Frascati Superconductivity Laboratory. The cable is designed to carry up to 20 kA at 5 K and 12 T and is composed of five stacks of 30 YBCO tapes each, arranged in a twisted stacked configuration inside an aluminum stabilizer and an external jacket. The cooling is provided by forced convection of supercritical helium that flows in a central channel and in cavities manufactured between the superconducting stacks and the aluminum core. A first dummy prototype of the cable has been produced by TRATOS Cavi S.p.A., Italy, in order to assess the feasibility of the manufacturing process. This paper presents a 3-D coupled electric and thermal model of the cable, developed at the University of Bologna in a COMSOL Multiphysics environment. The model adopts a homogenization procedure to describe the tape stacks in a finite-element method approach with considerable saving on the number of degrees of freedom. The model is applied to the computation of the cable current sharing temperature and to the investigation of quench due to a distributed disturbance.