High normal zone propagation velocity in copper-stabilized 2G HTS coated conductors

Abstract

Copper-stabilized second generation high-temperature superconductor (HTS) coated conductors were modified to enhance their normal zone propagation velocity (NZPV). Experimental results, supported by numerical simulations, indicate that adding copper on the substrate side instead of adding it on the HTS side increases the NZPV by a factor of 2–3. Furthermore, a novel tape architecture, called hybrid-current flow diverter (CFD), was investigated. This hybrid-CFD tape was designed with the goal of having a very long current transfer length, which is the key to enhance the NZPV. Results show that it is possible to fabricate an HTS tape with double stabilizer thickness in comparison to a bare tape, while accelerating the NZPV by a factor of three. With the same approach, a ten-fold increase of the NZPV can be expected for a tape with a 40 µm thick copper-stabilizer.

Normal zone propagation in various REBCO tape architectures

“…This measurement has been repeated for different current pulse amplitudes to obtain the dependance of the NZPV with the applied current. For more examples about NZPV measurements, see [18,24,28].…”

“…The buffer layers-CFD (or bCFD) architecture was proposed in [26] and experimentally demonstrated in [18,27]. In this work, tapes with a bCFD architecture were fabricated using a sulfidation process.…”

“…Therefore, understanding the parameters that affect the NZPV becomes essential when designing tape architectures to be used in specific applications. For example, it has been demonstrated experimentally that the addition of a metallic shunt such as copper or stainless steel reduces the NZPV [17,18]. In this work, the NZPV of REBCO tapes with different architectures fabricated in the context of the FASTGRID project was investigated both experimentally and numerically at 77 K. The results were analyzed to highlight the main parameters affecting the NZPV.…”

Quench Detection and Protection for High-Temperature Superconductor Accelerator Magnets

“…The observed improvement is, however, somewhat limited, and may still be insufficient to enable the use of conventional voltage-based quench detection schemes. An interesting approach to increasing the NZPV in coated conductors by means of increasing interfacial resistance between the superconductor and stabilizer was proposed in [100] and further developed in [101]. Effects of the interfacial resistance on the current transfer between the superconductor and the stabilizer layer were studied in detail by Levin et al [24], who showed that the current diffusion length L = R int d n /ρ n , where R int is the interfacial resistance and d n and ρ n are stabilizer thickness and normal state resistivity, respectively; where it replaces the thermal diffusion length in the heat transfer equation, leading to a faster quench propagation.…”

Influence of Local Inhomogeneities in the REBCO Layer on the Mechanism of Quench Onset in 2G HTS Tapes

“…Other ways exist to study the longitudinal propagation of the dissipation along the length of the tape. The use of fluorescent paint [6] enables the observation of the temperature elevation on the tape or electrical measurements through voltage taps positioned on the tape surface help to measure the Normal Zone Velocity Propagation (NZVP) [7] of these dissipation columns.…”