Current sharing between superconducting film and normal metal

Levin, Gilbert V.; Barnes, Paul N.; Bulmer, John

doi:10.1088/0953-2048/20/8/006

Cited by 25 publications

(34 citation statements)

References 22 publications

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“…The potential V s in the superconducting film is determined by the equation of conservation of the twodimensional density of current J s (A/cm) [8] …”

Section: Current Exchange Within Coated Conductormentioning

confidence: 99%

“…(12) [13]. Therefore, the details of the current exchange that takes place on the spatial scale of the order of λ 1 in many situations can be accurately described by assuming that the potential of the superconductor is constant or piecewise constant [8].…”

Section: Current Exchange Within Coated Conductormentioning

confidence: 99%

“…This approximation means that we neglect the right-hand side of Eq. (13) due to the large values of Λ i [8].…”

Section: Normal Zone: Weak Link Scenariomentioning

confidence: 99%

“…(19) and (23) are no longer valid, at least in the area of the largest field |E int |. More importantly, the power loss is no longer equally split between the stabilizer and the interface [8].…”

Section: Electric Field Across the Buffer And Interfacementioning

confidence: 99%

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The normal zone in YBa₂Cu₃O_6+x-coated conductors

Levin

Barnes

2007

Supercond. Sci. Technol.

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We consider the distribution of an electric field in YBCO-coated conductors for a situation in which the DC transport current is forced into the copper stabilizer due to a weak link -a section of the superconducting film with a critical current less than the transport current. The electric field in the metal substrate is also discussed. The results are compared with recent experiments on normal zone propagation in coated conductors for which the substrate and stabilizer are insulated from each other. The potential difference between the substrate and stabilizer, and the electric field in the substrate outside the normal zone can be accounted for by a large screening length in the substrate, comparable to the length of the sample. During a quench, the electric field inside the interface between YBCO and stabilizer, as well as in the buffer layer, can be several orders of magnitude greater than the longitudinal macroscopic electric field inside the normal zone. We speculate on the possibility of using possible microscopic electric discharges caused by this large (∼kV/cm) electric field as a means to detect a quench.

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“…The potential V s in the superconducting film is determined by the equation of conservation of the twodimensional density of current J s (A/cm) [8] …”

Section: Current Exchange Within Coated Conductormentioning

confidence: 99%

Section: Current Exchange Within Coated Conductormentioning

confidence: 99%

“…This approximation means that we neglect the right-hand side of Eq. (13) due to the large values of Λ i [8].…”

Section: Normal Zone: Weak Link Scenariomentioning

confidence: 99%

Section: Electric Field Across the Buffer And Interfacementioning

confidence: 99%

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The normal zone in YBa₂Cu₃O_6+x-coated conductors

Levin

Barnes

2007

Supercond. Sci. Technol.

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“…Such a "reversed" voltage anomaly in a current-voltage characteristic of HTS tape is often associated with the resistive transition that occurs outside of the segment between the voltage taps, but diverts some current into the stabilizer layer of that segment due to a finite current diffusion length. 21 The net heat release in the conductor estimated as power integrated over the duration of the ramp is $1.27 mJ. By using temperature-dependent values for the heat capacities of the conductor materials, and assuming the normal zone length along the tape of 1 mm, this heat amount yields a local temperature rise of $0.6 K (or a proportionally smaller number for a larger-sized normal zone) in adiabatic approximation.…”

mentioning

confidence: 99%

Acoustic thermometry for detecting quenches in superconducting coils and conductor stacks

Marchevsky

Gourlay

2017

Applied Physics Letters

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Quench detection capability is essential for reliable operation and protection of superconducting magnets, coils, cables, and machinery. We propose a quench detection technique based on sensing local temperature variations in the bulk of a superconducting winding by monitoring its transient acoustic response. Our approach is primarily aimed at coils and devices built with high-temperature superconductor materials where quench detection using standard voltage-based techniques may be inefficient due to the slow velocity of quench propagation. The acoustic sensing technique is non-invasive, fast, and capable of detecting temperature variations of less than 1 K in the interior of the superconductor cable stack in a 77 K cryogenic environment. We show results of finite element modeling and experiments conducted on a model superconductor stack demonstrating viability of the technique for practical quench detection, discuss sensitivity limits of the technique, and its various applications.

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