Alternating Over-Current Characteristics of HTSC Tape Using DFT

The quench characteristics of high-T
_C
superconducting (HTSC) tape for alternating over-current applications have been investigated at various amplitudes of the over-current and its quench developments have been analysed by applying discrete Fourier transform (DFT) for the voltage and the current waveforms of HTSC tape. Generally, the HTSC tape shows a broad superconducting and normal transition region above its critical current due to the metal sheath unlike HTSC thin film or HTSC bulk. Moreover, the voltage-current characteristics of HTSC tape are complicated because the quench and the recovery between the superconducting state and the normal state are repeated. In this paper, the alternating over-current experiments for the HTSC tape were performed to analyse its quench developments. The fundamental frequency components for the current and the voltage waveforms of the HTSC tape were abstracted by applying DFT. From those fundamental frequency components, the numerical formula for HTSC tape's resistance has been derived. By applying its numerical formula into circuit equation, the quench developments of HTSC tape dependent on alternating over-current have been estimated and the agreement with the experimental results has been found