Eddy Current Loss in Superconducting Cable-in-Conduit Conductor (CICC)

The Conductor of the toroidal field (TF) coils in Tokamaks are exposed to high amplitude (B
_m
≥ 2 T) pulse magnetic field (PMF) parallel to conductor axis during plasma disruption. A new experimental method for losses investigation in superconducting cable-in-conduit conductor (CICC) was used in this work. The method is based on a high sensibility of gas pressure in a closed volume to the energy input and allows measuring hysteresis losses with sufficient precision (when the decay rate of PMF is small) and the sum of hysteresis and eddy current losses (when the decay rate of PMF is high). Eddy current losses are rather higher than the coupling ones in CICC when PMF is parallel to the conductor axis. Therefore short samples (length is smaller than the last twist pitch) can be used for such investigations. The test facility for investigating the losses was developed and manufacturing at the “Kurchatov Institute”. The sample of the ITER TF conductor was exposed to PMF with different amplitude and electromagnetic time constant. As result of the experimental investigation the electromagnetic time constant and the resistivity of the bundle were determined. The maximum temperature of the strands during PMF exposure was calculated numerically.