Time-domain analysis of shielding current density in high-temperature Superconductor

The numerical code has been developed for the time-domain analysis of the shielding current density in the high-temperature superconductor (HTS). By means of the code, the shielding current density is calculated in cases where the ac current flows in a 1-turn coil placed just above the HTS. The voltage induced in the coil is evaluated as a function of time and its spectral analysis is performed. The results of computations show that, above a certain limit of the coil current, the third-harmonic voltage is suddenly excited and it grows more rapidly than any other harmonic voltage. It is also found that, if the dc magnetic field as well as the coil field is applied, the square root of the third-harmonic voltage is proportional to the coil current.