The effects of superconductor–stabilizer interfacial resistance on quenching of a pancake coil made out of coated conductor

Levin, Gilbert V.; Jones, Wesley A.; Novak, Kyle A.; Barnes, Paul N.

doi:10.1088/0953-2048/24/3/035015

Cited by 17 publications

(13 citation statements)

References 18 publications

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“…An approach to reduce or even avoid the shunt compromise in SFCLs and magnets is to intentionally increase the interfacial resistance (Ω·cm 2 ) between the HTS and the metallic shunt in order to increase the current transfer length (CTL). , This concept has proven that it can boost the NZPV of commercial tapes in a range of 25–100 times . Although effective, this method makes the CC impractical for applications where current leads (current contacts) are required for injecting current.…”

Section: Introductionmentioning

confidence: 99%

Chemical Solution Deposition of Insulating Yttria Nanolayers as Current Flow Diverter in Superconducting GdBa₂Cu₃O_7−δ Coated Conductors

et al. 2022

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The primary benefit of a metallic stabilization/shunt in high temperature superconductor (HTS) coated conductors (CCs) is to prevent joule heating damage by providing an alternative path for the current flow during the HTS normal state transition (i.e., quench). However, the shunt presence in combination with unavoidable fluctuations in the critical current ( I c ) of the HTS film can develop a localized quench along the CC’s length if the operational current is kept close to I c . This scenario, also known as the hot-spot regime, can lead to the rupture of the CC if the local quench does not propagate fast enough. The current flow diverter (CFD) is the CC architecture concept that has proven to increase the conductor’s robustness against a hot-spot regime by simply boosting the quench velocity in the CC, which avoids the shunt compromise in some applications. This work investigates a practical manufacturing route for incorporating the CFD architecture in a reel-to-reel system via the preparation of yttrium oxide (Y 2 O 3 ) as an insulating thin nanolayer (∼100 nm) on top of a GdBa 2 Cu 3 O 7 (GdBCO) superconductor. Chemical solution deposition (CSD) using ink jet printing (IJP) is shown to be a suitable manufacturing approach. Two sequences of the experimental steps have been investigated, where oxygenation of the GdBCO layer is performed after or before the solution deposition and the Y 2 O 3 nanolayer thermal treatment formation step. A correlated analysis of the microstructure, in situ oxygenation kinetics, and superconducting properties of the Ag/Y 2 O 3 /GdBCO trilayer processed under different conditions shows that a new customized functional CC can be prepared. The successful achievement of the CFD effect in the case of the preoxygenated customized CC was confirmed by measuring the current transfer length, thus demonstrating the effectiveness of the CSD-IJP as a processing method.

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Section: Introductionmentioning

confidence: 99%

Chemical Solution Deposition of Insulating Yttria Nanolayers as Current Flow Diverter in Superconducting GdBa₂Cu₃O_7−δ Coated Conductors

et al. 2022

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“…Recently, a number of papers have dealt with the stability and quench protection of YBCO coils [12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27] in a more microscopic fashion, including normal zone propagation along the conductor and between layers. Iwasa et al [24,25] first investigated these issues for YBCO coils and demonstrated that the YBCO-coated conductor must be loaded with several tens of µm thick copper stabilizer to provide coil stability and quench protection.…”

Section: Introductionmentioning

confidence: 99%

The mechanism of thermal runaway due to continuous local disturbances in the YBCO-coated conductor coil winding

Yanagisawa

Okuyama

Nakagome

et al. 2012

Supercond. Sci. Technol.

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Though YBCO coils are stable against transient disturbances such as conductor motion, they suffer from thermal runaway at a current below the coil critical current due to continuous local disturbances attributed to partial degradation of the conductor in the coil winding. Continuous heat generation in the degraded layer induces thermal runaway in adjacent layers; thermal runaway does not occur in the degraded layer spontaneously due to the small n index of the degraded YBCO-coated conductor. The thermal runaway current depends on the cooling conditions of the winding. For a paraffin-impregnated YBCO coil under quasi-adiabatic conditions, the thermal runaway current is far below the coil critical current, while it is close to the coil critical current in the case of a dry-wound coil. The permissible temperature rise following a thermal runaway for YBCO conductors in the degraded layer is demonstrated to be 340 K. If the YBCO coils are operated at a temperature below 20 K, the current density, typically 600-800 A mm −2 , is much higher than that at 77 K. Therefore, the time interval between thermal runaway initiation and the melting temperature becomes less than 0.5 s, posing a difficult problem for protection; i.e., thermal runaway due to continuous local disturbances is hazardous to the safe operation of high current density YBCO coils.

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“…It is necessary to focus on studying the quenching characteristic of YBCO material to realize the engineering application of R-SFCL. At present, many scholars have conducted extensive and in-depth research on the different characteristics of YBCO superconducting tape including quenching behavior under AC or DC overcurrent [15,16,17,18,19,20,21,22], quench propagation [23,24,25,26], quenching recovery [27,28,29,30], thermal and mechanical properties [31,32], minimum quench energy [33,34], maximum operating condition [35], and the effect of different materials on quenching behavior [36,37,38], which provide a solid foundation for the use of superconducting tape in design and fabrication of R-SFCL. However, there are few studies on common characteristics of quenching resistance of 2G HTS tape under AC and DC overcurrent, which is necessary and basic for R-SFCL design and research.…”

Section: Introductionmentioning

confidence: 99%

Study on Quenching Characteristics and Resistance Equivalent Estimation Method of Second-Generation High Temperature Superconducting Tape under Different Overcurrent

Liang

Ren

et al. 2019

Materials

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In this paper, through AC and DC overcurrent tests on second generation high temperature superconducting tape (2G HTS tape), we respectively summarize the typical types of quenching resistance and corresponding quenching degree, in which there are three types under AC overcurrent and two types under DC overcurrent. According to experimental results, a rule was found that, when 2G HTS tape quenches to normal state, the relationship between quenching resistance and joule heat generated from 2G HTS tape presents a fixed trend line, and the influence of liquid nitrogen can be ignored. Then, the characteristics and rules of quenching resistance found in experiments are well explained and confirmed by a detailed 3D finite element model of 2G HTS tape including electromagnetic field and thermal field. Finally, based on above works, our group proposes a new equivalent method to estimate the quenching resistance, where the results of AC and DC overcurrent experiments can be equivalent to each other within a certain range. Compared with FEM, the method has the following advantages: (i) The method is simple and easy to implement. (ii) This method combines precision and computational efficiency. (iii) With superconducting tape quenching to normal state, this method presents a good consistency with experimental results.

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The effects of superconductor–stabilizer interfacial resistance on quenching of a pancake coil made out of coated conductor

Cited by 17 publications

References 18 publications

Chemical Solution Deposition of Insulating Yttria Nanolayers as Current Flow Diverter in Superconducting GdBa₂Cu₃O_7−δ Coated Conductors

Chemical Solution Deposition of Insulating Yttria Nanolayers as Current Flow Diverter in Superconducting GdBa₂Cu₃O_7−δ Coated Conductors

The mechanism of thermal runaway due to continuous local disturbances in the YBCO-coated conductor coil winding

Study on Quenching Characteristics and Resistance Equivalent Estimation Method of Second-Generation High Temperature Superconducting Tape under Different Overcurrent

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The effects of superconductor–stabilizer interfacial resistance on quenching of a pancake coil made out of coated conductor

Cited by 17 publications

References 18 publications

Chemical Solution Deposition of Insulating Yttria Nanolayers as Current Flow Diverter in Superconducting GdBa2Cu3O7−δ Coated Conductors

Chemical Solution Deposition of Insulating Yttria Nanolayers as Current Flow Diverter in Superconducting GdBa2Cu3O7−δ Coated Conductors

The mechanism of thermal runaway due to continuous local disturbances in the YBCO-coated conductor coil winding

Study on Quenching Characteristics and Resistance Equivalent Estimation Method of Second-Generation High Temperature Superconducting Tape under Different Overcurrent

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Chemical Solution Deposition of Insulating Yttria Nanolayers as Current Flow Diverter in Superconducting GdBa₂Cu₃O_7−δ Coated Conductors

Chemical Solution Deposition of Insulating Yttria Nanolayers as Current Flow Diverter in Superconducting GdBa₂Cu₃O_7−δ Coated Conductors