Coupled electromagnetic and thermal analysis of magnets wound from cable-in-conduit conductors

Abstract

Investigating the electromagnetic and thermal processes inside the conductor of a superconducting magnet delivers valuable knowledge for predicting its performance. However, for cable-in-conduit conductors (CICCs) with up to over 1000 strands, a detailed investigation by means of experiments is virtually impossible. In this paper, a modelling approach is presented using lumped elements for both an electromagnetic and a thermo-hydraulic model of the CICC. The models are coupled and allow the detailed investigation on strand level as well as the prediction of the overall performance of a conductor. The combined model considers heat conduction in the strands and the jacket, their heat capacity, the coolant flow, the transient heat transfer from strand to helium, heat-induced flow, transverse electrical conductivity between strands, complete magnetic coupling, and current sharing. The dependence of the critical current density on temperature and magnetic field is implemented. Preliminary results for current distribution processes in the QUELL conductor are presented. While this work is focused on CICCs, the technique can readily be adapted to other types of multistrand conductors.