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Your search keyword '"Knoll, David C."' showing total 6 results
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6 results on '"Knoll, David C."'

1. Experimental and numerical studies of the effect of phase difference between transport current and perpendicular applied magnetic field on total ac loss in Ag-sheathed (Bi, Pb)2Sr2Ca2Cu3O(sub x)

Author

Nguyen, Doan Ngoc, Knoll, David C., Guomin Zhang, Schwartz, Justin, and Sastry, Pamidi V.P.S.S.

Subjects
Silver compounds -- Magnetic properties, Superconductors -- Magnetic properties, Copper compounds -- Magnetic properties, Physics
Abstract

Numerical calculations using Brandt's model are used to study the effects of phase differences between transport current and applied magnetic field on ac losses in superconductors. The effects of the phase difference (DELTA phi) on the individual components of transport loss and magnetization loss are calculated.

Published
2005

3. Experimental and numerical studies of the effect of phase difference between transport current and perpendicular applied magnetic field on total ac loss in Ag-sheathed (Bi,Pb)2Sr2Ca2Cu3Ox tape.

Author

Doan Ngoc Nguyen, Sastry, Pamidi V. P. S. S., Knoll, David C., Guomin Zhang, and Schwartz, Justin

Subjects
MAGNETIC fields, SUPERCONDUCTORS, DENSITY currents, CALORIMETRY, MAGNETIZATION, PHYSICS
Abstract

The effect of phase difference between transport current and perpendicular applied magnetic field, Δφ, on total ac loss in multifilamentary, silver-sheathed (Bi,Pb)2Sr2Ca2Cu3Ox (Bi-2223) superconducting tapes was calculated numerically using Brandt’s equation [Phys. Rev. B 54, 4246 (1996)] and the results were compared with experimental results obtained by the calorimetric method. In the numerical calculations, the superconducting transition was modeled by E-J characteristics represented by a power law. The dependence of critical current density on the n value was taken into account. The dependence of critical current density and n value on applied magnetic field was obtained from experimental data. It was observed that Δφ has a significant effect on the loss behavior of Bi-2223 tapes and depends strongly on the relative values of transport current and applied magnetic field. The effects of Δφ on the individual components of transport loss and magnetization loss were also calculated. Good agreement between the calculated and experimental results is demonstrated. [ABSTRACT FROM AUTHOR]

Published
2005
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6. Relationship between Critical Current Density and Self-Field Losses of Ag-Sheathed (Bi,Pb)2Sr2Ca2Cu3Ox Superconducting Tapes.

Author

Nguyen, Doan N., Sastry, Pamidi V. P. S. S., Guomin Zhang, Knoll, David C., and Schwartz, Justin

Subjects
CRITICAL currents, SUPERCONDUCTIVITY, HIGH temperature superconductors, HIGH temperature superconductivity, LOW energy electron diffraction, ELECTRON diffraction
Abstract

The critical current of (Bi,Pb)2Sr2Ca2Cu3Ox (Bi-2223) was varied between 2 A and 120 A using three different approaches: field angle with respect to the wide face of the tape, mechanical strain, and heat treatments. The results of transport loss measurements carried out on the three sets of samples showed that reduced critical current density caused an increase in AC loss as expected from Norris’s model. Comparison of the data among the three sets, however, showed some interesting features in the dependence of the AC loss behavior on the method used to vary critical current density. The results are explained based on the type of defects, localized or distributed, caused by the particular approach used in lowering the critical current. © 2006 American Institute of Physics [ABSTRACT FROM AUTHOR]

Published
2006
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