Local Investigation of Spatial Homogeneity in 600 A/cm-w Class ${\hbox {GdBa}}_{2}{\hbox {Cu}}_{3}{\hbox {O}}_{7-\delta}$ PLD Coated Conductor

Matsekh, Arkadiy; Inoue, Masayoshi; Kiss, Takanobu; Iijima, Y.; Saitoh, Takashi; Izumi, Teruo

doi:10.1109/tasc.2010.2096490

Cited by 5 publications

(2 citation statements)

References 16 publications

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“…The problem of nonuniform current distribution caused by imperfections [3][4][5][6][7][8] has been extensively studied for wires made of high-temperature superconductors (HTS) by magnetic field mapping [9][10][11][12][13][14][15][16], magneto-optical imaging [17,18] and scanning laser microscopy [19]. Analytical expressions for the electrical field distribution caused by a crack in the superconductor [20], and for the current transfer in stabilizing the metallic matrix [21] have been developed.…”

Section: Introductionmentioning

confidence: 99%

Impact of critical current fluctuations on the performance of a coated conductor tape

Gömöry

Šouc

Adámek

et al. 2019

Supercond. Sci. Technol.

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Coated conductor (CC) tapes often exhibit critical current, Ic, which fluctuates along the length coordinate, x, leading to an Ic(x) dependence. The need to reduce the price of these tapes does not favor a decrease in the variation of Ic in the near future. Therefore, it is reasonable to develop a method for estimating the possible impact of such fluctuating transport ability on the performance of superconducting devices. Fortunately, providing Ic(x) data together with the delivered conductor is becoming a standard approach among CC tape producers, and in-depth analysis of such data is now possible. Extrapolation of the short sample testing methodology to the case of a device incorporating many meters of CC tape leads to the introduction of an ‘overall critical current’ as a value generating 1 μV cm−1 of electric field over the whole conductor. We show that in the case of Ic(x) fluctuations obeying the Gaussian distribution one can predict the value of the overall critical current from the mean value and the variance of the Ic(x) data set. Deviation from the Gaussian distribution found in real tapes would cause a further reduction of the overall critical current. Conversely, in the case of strong dropouts in the critical current value, a statistical approach is useless and one must analyze the probability of the weakest location developing in a hot spot with a dramatic increase of temperature. Extending the analysis for a single tape to cables and coils results in a rather simple summary: when current sharing is possible, the reduction of overall critical current with respect to its mean value is significantly depressed. This favors the parallel arrangement of tapes with low contact resistance allowing current migration from tape to tape. On the other hand, the insulation of tapes leads to the same overall critical current reduction as observed for a single tape.

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Section: Introductionmentioning

confidence: 99%

Impact of critical current fluctuations on the performance of a coated conductor tape

Gömöry

Šouc

Adámek

et al. 2019

Supercond. Sci. Technol.

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“…Hot spots originating from inhomogeneity have been identified in some cases as the limitation of high-field magnet performance [30,[53][54][55], and contributed to the conservative design concept, substantially limiting the exploitation of the conductor transport capability [56]. Delivering the information about the I c (x) distribution together with the supplied tape has become a common practice thanks to the development of scanning techniques [37,[57][58][59] suitable for long-length reelto-reel inspection [60][61][62][63].…”

Section: Introductionmentioning

confidence: 99%

Stability of DC transport in HTS conductor with local critical current reduction

Gömöry

Šouc

2021

Supercond. Sci. Technol.

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A common feature of commercially available conductors based on high-temperature superconducting compounds is the fluctuation of critical current along the length. Fortunately, the practice adopted by manufacturers nowadays is to supply the detailed I c(x) data with the conductor. Compared to knowing just the average of critical current, this should also allow a much better prediction of the conductor performance. Statistical methods are suitable for this purpose in the case when the fluctuations are regular at the low end of critical current distribution. However, a different approach is necessary at the presence of ‘weak spots’ that drop out of any statistics. Because of the strong nonlinearity of the current–voltage curve, such a location could transform into a ‘hot spot’ at transporting direct current (DC), with an abrupt increase of temperature endangering the conductor operation. We present a set of analytical formulas including the prediction of the maximum DC that could be carried sustainably before the thermal runaway appears. It is necessary to know the cooling conditions as well as the properties of the conductor constituents and their architecture. A formula for the voltage appearing on a weak spot, and its dependence on the DC, is also proposed. For this purpose the result of previous theoretical work has been slightly modified after comparing it with numerical iterative computations and finite element modeling. We demonstrate that the derived model allows a powerful analysis of experimental data comprising an estimation of the weak spot parameters i.e. its critical current and the length of the defect zone.

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Epitaxial growth of CaTiO3 buffer layer for fabrication of c-axis oriented YBCO film by sol-gel method

Zhang

Ding

et al. 2016

J Sol-Gel Sci Technol

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Local Investigation of Spatial Homogeneity in 600 A/cm-w Class ${\hbox {GdBa}}_{2}{\hbox {Cu}}_{3}{\hbox {O}}_{7-\delta}$ PLD Coated Conductor

Cited by 5 publications

References 16 publications

Impact of critical current fluctuations on the performance of a coated conductor tape

Impact of critical current fluctuations on the performance of a coated conductor tape

Stability of DC transport in HTS conductor with local critical current reduction

Epitaxial growth of CaTiO3 buffer layer for fabrication of c-axis oriented YBCO film by sol-gel method

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