Analysis of AC Losses in a CS Conductor Sample for the ITER Project

The cable-in-conduit conductors (CICCs) that will be adopted for the ITER central solenoid (CS) coil of the ITER machine have been extensively characterized in the SULTAN facility in Villigen, Switzerland, by means of DC and AC tests. The AC measurements were performed superimposing a sinusoidal magnetic field, with the amplitude of 0.2-0.3 T and frequency in the range of 0.1-5 Hz, to a background constant magnetic flux density of 2 T and 9 T. This paper describes the analysis of the AC loss SULTAN tests of one CICC, identical to that used for the manufacturing of the CS Insert tested in 2015 in the CSMC facility in Naka, Japan. The numerical analysis of these experiments was performed by means of the THELMA code, by developing three models at different levels of discretization (sub-cables of different cabling stages and strands). The comparison between measured and computed losses allows one to estimate the interstrand contact conductances of the tested sample. The model provides a useful insight on the time and space distribution of the power dissipated in the conductor