AC Loss in HTS Fusion Cables: Measurements, Modeling, and Scaling Laws

Currently, the use of high-temperature superconducting (HTS) cables in the high-field sections of central solenoid (CS) of DEMO is one of the most appealing applications of the HTS cables in fusion magnets. Due to the pulsed operation of such coils minimization of the ac loss is necessary for the CS conductors. For the stacked-tape HTS cable layout proposed at the Swiss Plasma Center (SPC), the main contributions in the total ac loss-hysteresis loss in stacks, intra- and inter-strand coupling losses-have been studied. The electrical network model is used for the coupling losses, based on which the scaling laws for the ac energy loss are proposed. On the basis of the developed numerical tools, the assessment of the ac loss for the next HTS cable prototypes at SPC is also reported. More than 50% reduction of the total ac loss is expected compared with the first TF cable prototypes tested in the European DIPOle (EDIPO).