High normal zone propagation velocity in second generation high-temperature superconductor coated conductors with a current flow diverter architecture

A high normal zone propagation velocity (NZPV) is a desirable feature in second generation (2G) high-temperature superconductor (HTS) coated conductors (CCs) in order to reduce the probability of developing destructive hot spots. In this work we investigated experimentally the impact of inserting a highly resistive layer that partially covers the HTS–stabilizer interface of 2G HTS CCs. This new layer was called a 'current flow diverter' (CFD). The purpose of the CFD is to concentrate the current at the edges of the tape when the current transfers from the HTS to the stabilizer upon a quench event. A series of commercial 2G HTS tapes were modified in order to integrate a CFD into them. Measurements realized on these modified tapes showed that the CFD architecture allowed the NZPV to be enhanced by at least two orders of magnitude in comparison with unmodified commercial tapes. Furthermore, it was shown that the NZPV can be significantly enhanced with a very small increase in the HTS–stabilizer interfacial resistance, which is of prime importance for the reliability of current contacts in real applications. (paper)