Enhanced normal zone propagation velocity in REBCO coated conductors using an intermetallic stabilizer coating

ABSTRACT: The Current Flow Diverter (CFD) is an established concept that has proven to effectively reduce the probability of destructive hot spots by boosting the normal zone propagation velocity (NZPV) in commercial REBa₂Cu₃O₇ (REBCO; RE = Rare Earth) coated conductors (CC). However, incorporating the CFD concept requires finding a scalable method that is also compatible with the already established R2R fabrication process used by CC manufacturers. This study presents a new simple & cost-effective proof-of-concept technique capable of recreating the CFD architecture in commercial CCs coated with silver. The technique is based on promoting a locally controlled thin film diffusion reaction between the silver stabilizer and pure indium. Due to fast diffusion in the Ag-In system, stable Intermetallic Compounds (IMC) are formed throughout the whole thickness of the silver layer reaching the REBCO interface. The presence of Ag-In IMC in the interface safely increases the interfacial resistance (Ω-cm²) by orders of magnitude, thus allowing to safely form the CFD interlayer. Silver-coated tape samples altered using this CFD-IMC have shown an NZPV increase of 5-8x when compared with pristine samples

Normal zone propagation in various REBCO tape architectures

The normal zone propagation velocity (NZPV) of three families of REBCO tape architectures designed for superconducting fault current limiters and to be used in high voltage direct current transmission systems has been measured experimentally in liquid nitrogen at atmospheric pressure. The measured NZPVs span more than three orders of magnitude depending on the tape architectures. Numerical simulations based on finite elements allow us to reproduce the experiments well. The dynamic current transfer length (CTL) extracted from the numerical simulations was found to be the dominating characteristic length determining the NZPV instead of the thermal diffusion length. We therefore propose a simple analytical model, whose key parameters are the dynamic CTL, the heat capacity and the resistive losses in the metallic layers, to calculate the NZPV.The authors acknowledge the funding of this research by FASTGRID Project (EU-H2020, 721019), the Projects COACHSUPENERGY (MAT2014-51778-C2-1-R), SUMATE (RTI2018-095853-BC21 and RTI2018-095853-B-C22) from the Spanish Ministry of Economy and Competitiveness which were cofunded by the European Regional Development Fund, the Project 2017-SGR 753 from Generalitat de Catalunya and the COST Action NANOCOHYBRI (CA16218). Polytechnique Montréal authors also acknowledge NSERC (Canada), FRQNT (Québec), the RQMP infrastructure and CMC microsystems for financial support. ICMAB authors also acknowledge the Center of Excellence awards Severo Ochoa SEV-2015-0496 and CEX2019-000917-S.With funding from the Spanish government through the ‘Severo Ochoa Centre of Excellence’ accreditation (CEX2019-000917-S).Peer reviewe