Experimental Study and Frequency Domain Analysis on Metal-Insulation HTS Coil

This work reports a frequency domain analysis on alternating current (AC) response of a metal-insulation (MI) high temperature superconducting (HTS) coil. An 85-turn MI test coil was wound and operated in a liquid nitrogen bath at 77 K. Sinusoidal current was applied to the test coil to measure the AC responses. The test coil’s total voltage and the central magnetic field were measured from 0.01 Hz to 5 Hz. The phase difference between the total voltage and the azimuthal current was calculated from the measured data. To explain the phase difference between the total voltage and the azimuthal current, the additional frequency-dependent resistive component was adopted. The results demonstrate that the discrepancy between the measurement and the simulation results from the lumped-circuit model tends to increase with frequency.