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Your search keyword '"Zeimetz, B."' showing total 31 results
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31 results on '"Zeimetz, B."'

1. Application of Percolation Theory to Current Transfer in Granular Superconductors

Author

Zeimetz, B., Glowacki, B. A., and Evetts, J. E.

Subjects
Condensed Matter - Superconductivity
Abstract

We investigate the description of current transfer in polycrystalline superconductors by percolation theory and its limitations. Various computer models that have been proposed are reviewed and related to the experimental and theoretical framework. While some conductor properties can be well described by percolation theory and models, we argue that a conceptual gap exists between experiment and theory. This gap has to be bridged by finding relations between electromagnetic and statistical parameters. We derive various such relations and compare them with recent simulation data. In particular, we suggest a new scaling law between the two fundamental variables current and probability., Comment: submitted to European Physical Journal B, April 2002, 18 pages revised and re-submitted June 2002; added remarks and references [15-18] on Correlated Percolation; corrected minor errors; updated some references

Published
2002
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2. Superconducting properties of the powder-in-tube Cu-Mg-B and Ag-Mg-B wires

Author

Glowacki, B. A., Majoros, M., Vickers, M. E., and Zeimetz, B.

Subjects
Condensed Matter - Superconductivity, Condensed Matter - Materials Science
Abstract

The new class of Mg-B superconducting conductors was prepared using the standard in-situ powder-in-tube, PIT, method where Mg+2B mixture was used to fill the copper and silver tubes. Study of the intergranular current, grain connectivity and superconducting phases in wires were conducted by AC susceptibility measurements and direct four point transport measurements. Using SQUID magnetometer, magnetisation versus magnetic field (M-H) curves of the round wires after reactive diffusion were measured at temperatures 5K and magnetic field up to 5T to define the Jcmag . The direct current density measurements of the in-situ Cu-MgB2 performed at 4.2K gave the value of 10^9 Am-2 ., Comment: Paper presented at EUCAS'01 conference, Copenhagen, 26 - 30 August 2001

Published
2001
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3. Numerical simulation of AC current limiting by bulk Bi-2212 ceramic and 2G YBCO tapes

Author

Velichko, A.V., Zeimetz, B., and Coombs, T.A.

Subjects
Superconductivity -- Measurement, Numerical analysis, Business, Electronics, Electronics and electrical industries
Abstract

The high-aspect ratio problem relevant to the numerical simulation of current limiting properties of High Temperature Superconducting (HTS) tapes is discussed. Findings reveal that the replacement of the actual-size simulation cells with enhanced size effective cells can reduce the simulating time and enhance feasibility for samples with aspect ratio as high as 10,000.

Published
2007

5. Significantly enhanced critical current density in Bi-2223/Ag multifilamentary tapes by hot pressing

Author

Zeng, R., Ye, B., Horvat, J., Guo, Y.C., Zeimetz, B., Yang, X.F., Beales, T.P., Liu, H.K., and Dou, S.X.

Subjects
Flux pinning -- Research, Grain boundaries -- Research, Magnetic fields -- Research, Superconductors -- Research, Business, Electronics, Electronics and electrical industries
Abstract

A hot-pressing technique was used to fabricate Bi-2223/Ag multifilamentary tapes to investigate its effect on grain connectivity and flux pinning. After hot pressing, the critical current density in tapes was doubled. In a 19-filament tape, Jc increased from 26,000A/cm2 to 56,000A/cm2. Improved grain connectivity, reduced secondary phases and increased core density resulted from hot-pressing as shown by microstructural analysis. In addition, the fraction of strong links improved from 47% to 68% in a 19-filament tape.

Published
1999

6. High electrical performance Ag-sheathed Bi-2223 multifilamentary tapes prepared by an optimised PIT processing route

Author

Zeng, R., Yao, P., Zeimetz, B., Beales, T.P., Liu, H.K., and Dou, S.X.

Subjects
Bismuth -- Research, Metals -- Quenching, Microstructure -- Research, Business, Electronics, Electronics and electrical industries
Abstract

The effect of processing on microstructure and on Jc in PIT tapes was investigated by means of an optimized PIT processing route which is introduced and discussed from experiments. The highest Jc performance of 51,000A/cm2 had been obtained for 69-filamentary tapes at 77K and self field. The results showed that Jc is influenced on Pb distribution of Pb-2212, phase composition for the precursor powder, the core thickness and the deformation reduction rate.

Published
1999

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