Transport current distribution in (Bi,Pb)-2223/Ag tapes

Herrmann, Jan; Savvides, N.; Müller, K.‐H.; Zhao, R.; McCaughey, G.; Darmann, F.; Apperley, M.

doi:10.1109/77.784811

Cited by 5 publications

(1 citation statement)

References 12 publications

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“…Since the heating of the films we are considering will be caused by electrical current, this assumption is equivalent to assuming that the current density is uniform throughout the film. Explicit support for this comes from the work of Herrmann et al, 17,18 who found that in high-T c tapes current in excess of a certain characteristic cutoff (the value of which was slightly below the critical current) was indeed dis-tributed homogeneously across the entire superconductor cross section. Moreover, direct measurements on a slab of Bi-based crystal, using a microarray of Hall probes, show that although current is restricted to the lateral regions of the slab at relatively low temperature (T 50 K), nonuniformity becomes negligible above about 80 K, a temperature relatively near T c .…”

Section: A Constructing the Modelmentioning

confidence: 94%

Analytical approach to the thermal instability of superconducting films under high current densities

et al. 2011

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Using the Green's function of the 3D heat equation, we develop an analytical account of the thermal behaviour of superconducting films subjected to electrical currents larger than their critical current in the absence of an applied magnetic field. Our model assumes homogeneity of films and current density, and besides thermal coefficients employs parameters obtained by fitting to experimental electrical field -current density characteristics at constant bath temperature. We derive both a tractable dynamic equation for the real temperature of the film up to the supercritical current density J * (the lowest current density inducing transition to the normal state), and a thermal stability criterion that allows prediction of J * . For two typical YBCO films, J * predictions agree with observations to within 5%. These findings strongly support the hypothesis that a currentinduced thermal instability is generally the origin of the breakdown of superconductivity under high electrical current densities, at least at temperatures not too far from Tc.

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Section: A Constructing the Modelmentioning

confidence: 94%

Analytical approach to the thermal instability of superconducting films under high current densities

et al. 2011

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DC and AC self-magnetic field profiles of (6+1) filamentary BSCCO tapes with different filament arrangements measured by Hall probe magnetometry

Kvitkovič¹,

Majoroš²,

Apperley³

2002

Physica C: Superconductivity

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Errors in measurement of current distribution in a superconducting tape

Usak¹

2011

Supercond. Sci. Technol.

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The paper reports on the role of the typical mapping errors in measurement of the lateral sheet current distribution Iy(x) in a superconducting tape. The sheet current is calculated indirectly, from the mapped data of the self magnetic field of the superconducting layer. The field is generated by transport or induced current in a tape. In model calculations examples of the influence of the different types of errors on false shaping of the lateral sheet current profile are given. The field mapping is made outside and over the tape. The lateral profile Bz(x, z) of the magnetic field component, perpendicular to the superconducting layer, is input to the Biot–Savart inverse procedure. In the experiment we have used superconducting tape as a sample and an InSb Hall probe with active surface 20 × 20 µm2 as a magnetic field sensor. We demonstrate the details, together with obstacles and errors encountered in measurement and subsequent evaluation. The demonstrations serve for the reader to be aware of limits in interpretation of the measured data and to overcome the natural barrier in understanding, insight and use of this fruitful method.

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Transport current distribution in (Bi,Pb)-2223/Ag tapes

Cited by 5 publications

References 12 publications

Analytical approach to the thermal instability of superconducting films under high current densities

Analytical approach to the thermal instability of superconducting films under high current densities

DC and AC self-magnetic field profiles of (6+1) filamentary BSCCO tapes with different filament arrangements measured by Hall probe magnetometry

Errors in measurement of current distribution in a superconducting tape

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