Current Distribution in Superconducting Tapes During Fast Current Ramping Based on Modified Brandt's Method

To reduce the time and risk of sample damage during critical current characterization of long Coated Conductors (CC), a pulse current method is proposed previously. The dynamic current distribution in the tape during pulse current ramping is studied in this work for better understanding of the behavior of the CCs under measurement, based on a current-driven version of Brandt's method. in addition, a coil with 2000 turn was used in the experiment to improve the signal-to-noise ratio. The ramping rate is compared with the voltage criterion in the standard four-point measurements. Especially, a scaling behavior is found for simple but precise description of the effect of the current ramping rate on the measured critical current, utilizing the concept of an effect electric field, which can be used to calculate the critical current with commonly used criterion of 1 μV/cm, with no free parameter. Effects of copper protection layers are also considered for fast pulses. The numerical results are also compared with those of experiments.