Effect of Length Scale on Critical Current Measurement in High Temperature Superconductor Wires

Gannon, J. L.; Malozemoff, A. P.; Diehl, R.C.; Antaya, P.; Mori, Atsunobu

doi:10.1109/tasc.2013.2250113

Cited by 28 publications

(38 citation statements)

References 8 publications

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“…(i) The cracking of superconducting layer is reflected sharply in VI curve of short specimen (short resistance probedistance). 20) Therefore, from the viewpoint of materials characterization, it is important to obtain primary features in short specimen length range. (ii) The experimental gage length of specimen for measurement of I c and n-value under applied tensile stress is, in usual, limited to less than a few tens of centimeters.…”

Section: Introductionmentioning

confidence: 99%

“…21) Also the length-dependence of critical current has been accounted for by nonlinear current flow at defects 20) by application of the model of Friesen and Gurevich. 22) They treated with long tapes for practical design and application, using as-fabricated tape containing fabrica-tion process-induced defects.…”

Section: Introductionmentioning

confidence: 99%

“…The specimen length of the present work was far small in comparison with the other works. 20,21) However, as stated above, from the viewpoint of materials characterization, it is important to obtain primary features in short specimen length range where the influence of cracking of superconducting layer on VI curve is detected sharply. The technical merit of this work is to clarify the features in such a specimen length range.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Tape Length-Dependence of Critical Current and <i>n</i>-Value in Coated Conductor with a Local Crack

2014

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Tape length-dependence of voltagecurrent curve, critical current and n-value in a coated conductor with a local crack were studied by modeling analysis. In calculation, the specimen length was varied in the range of 1.5 to 18 cm where the influence of cracking of superconducting layer is sharply reflected in the voltagecurrent curve. The following results were obtained, which can be utilized for analysis and interpretation of the experimental results under applied tensile stress in laboratory scale of specimen length. The existence of a crack changed the critical current and n-value through the decrease in current-transportable cross-sectional area of the superconducting layer and the current shunting in the cracked cross-section for any specimen length and any crack size, while the extent of the change was dependent on specimen length and crack size. When the crack was large, critical current increased slightly and n-value decreased significantly with increasing specimen length due to the enhanced shunting current. On the other hand, when the crack was small, critical current increased slightly with specimen length due to the enhanced shunting current similarly to the case of large crack, but n-value decreased with increasing specimen length due to the enhanced shunting current but then it increased due to the enhanced voltage-development at higher voltage in the non-cracked part. Also, the features of the dependence of the relation of n-value to critical current on specimen length were revealed; the decrease in n-value with decreasing critical current became sharper for longer specimen.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Tape Length-Dependence of Critical Current and <i>n</i>-Value in Coated Conductor with a Local Crack

2014

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“…b) The MC method finds a sharp I c valley while the four-probe method shows moderate lower I c value of the section. The four-probe method measures the total voltage drop of the 0.5 m section, so I c value is averaged [15]. Yet as a continuous method, the MC method can locate the defect with better spatial resolution.…”

Section: A Comparison Of MC Methods and Four-probe Methodsmentioning

confidence: 99%

“…However, when it comes to an industrial long tape, the question becomes tortuous. Fourprobe measurements from end to end to the tape cannot give I c along the tape or find localized defects [15], so continuous I c measurement along the tape length is needed, realized through section-by-section four-probe method or non-contact method. The remaining problem is how to use the critical current distribution (I c (x), x represents the position in the tape) to evaluate the performance of the tape.…”

Section: Criterion For Assessing the Performance Of Long Hts Tapesmentioning

confidence: 99%

Examination and Analysis of Critical Current Uniformity of Long HTS Tapes by the MCorder

Zou

et al. 2015

IEEE Trans. Appl. Supercond.

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The magnetic circuit (MC) method has been developed to measure the critical current (I c ) of long high temperature superconductor (HTS) tapes continuously since 2010. So far, with the apparatus based on the MC method, namely MCorder, industrial HTS tapes produced by main manufactures worldwide have been measured using the MC method, including Bi2223/Ag multifilament tapes and coated conductors with/without magnetic substrates. The high speed (360 m/h), high accuracy measurement (resolution 1 A) and its adaption to all kinds of HTS tapes make large quantity measurement and statistical evaluation of HTS tape possible. In this paper, criteria for I c assessment of long HTS tapes is discussed, based on which analysis of samples from different manufacturers worldwide is provided. The measurement result of a Bi2223/Ag tape by MC method is compared with section-bysection four-probe method, and the two methods show good agreement. Fourier analysis is given for analyzing I c periodicity of a tape with periodical artificial defects.

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Longitudinal inhomogeneity of DC current transport properties in Gd-system HTS tapes – Statistical approach for system design

et al. 2014

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In this paper, we studied the DC current transport properties of GdBCO-coated conductors, including the longitudinal distribution of critical current. Inhomogeneity of the local critical current was firstly measured by means of TapeStar™ at 77 K, and then characterized based on a statistical method. Current transport properties were also measured for different positions and/or distances of potential taps using a four-probe method. It was shown that the longitudinal inhomogeneity of the conductor was described by use of a simplified percolation depinning model that takes account of Gaussian distribution. We further distinguished the above-mentioned inhomogeneity between statistical distribution and random failure. Influence of the aforementioned statistically distributed current transport properties on the magnet performance was also elucidated for simple pancake coils. This information is important as it provides guidance for practical system design.

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Effect of Length Scale on Critical Current Measurement in High Temperature Superconductor Wires

Cited by 28 publications

References 8 publications

Tape Length-Dependence of Critical Current and <i>n</i>-Value in Coated Conductor with a Local Crack

Tape Length-Dependence of Critical Current and <i>n</i>-Value in Coated Conductor with a Local Crack

Examination and Analysis of Critical Current Uniformity of Long HTS Tapes by the MCorder

Longitudinal inhomogeneity of DC current transport properties in Gd-system HTS tapes – Statistical approach for system design

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