Concept of a current flow diverter for accelerating the normal zone propagation velocity in 2G HTS coated conductors

In this paper, we propose a slight change in the architecture of second generation (2G) high temperature superconductor (HTS) coated conductors (CCs), in order to accelerate their normal zone propagation velocity (NZPV) and reduce the probability of developing hot spots. The concept described in this work is to insert a highly resistive layer (called a ‘current flow diverter’, CFD) at the superconductor–stabilizer interface of the 2G HTS CC. The CFD partially covers this interface, so when a normal zone appears the current that transfers from the superconducting layer to the metallic (stabilizer) layers is forced to circumvent the CFD in order to follow the path of least resistance. This results in a significant increase of the current transfer length and a better spatial distribution of heat generation, that help in increasing the NZPV. According to the numerical model developed in this paper, the CFD architecture allows us to obtain NZPV values of more than 20 m s−1, which is approximately two orders of magnitude faster than what has been measured so far on commercially available 2G HTS CCs. Furthermore, our calculations reveal that, for the same value of interfacial resistance, a tape with the CFD architecture can exhibit an NZPV more than 40 times higher than in the case of a similar tape with a uniform interfacial resistance.