The Influence of Pre-Existing Defects on the Bending Strain Behavior of Bi2Sr2Ca1Cu2Ox and (Bi,Pb)2Sr2Ca2Cu3Ox Ag-Sheathed Tapes

Polyanskii, A.A.; Polák, M.; Anderson, John W.; Zhang, W.; Hellstrom, E. E.; Larbalestier, D. C.

doi:10.1007/978-1-4757-9056-6_90

Cited by 4 publications

(5 citation statements)

References 10 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In contrast, a bend strain of 0.3% induces cracking across the whole core and seriously interrupts the current flow. Polyanskii et al (1998) also showed that regions of pre-existing cracks or other pre-existing defects are more sensitive to bending, and severe damage of the tape occurs already for strains of ≈0.1%. An interruption of the current path in Ag-sheathed Bi tapes may be related to a current shunting through the silver sheath.…”

Section: Bi-2212 and Bi-2223 Tapesmentioning

confidence: 90%

Magneto-optical studies of current distributions in high-T_csuperconductors

et al. 2002

View full text Add to dashboard Cite

In the past few years magneto-optical flux imaging (MOI) has come to take an increasing role in the investigation and understanding of critical current densities in high-T c superconductors (HTS). This has been related to the significant progress in quantitative high-resolution magnetooptical imaging of flux distributions together with the model-independent determination of the corresponding current distributions. We review in this article the magneto-optical imaging technique and experiments on thin films, single crystals, polycrystalline bulk ceramics, tapes and melt-textured HTS materials and analyse systematically the properties determining the spatial distribution and the magnitude of the supercurrents. First of all, the current distribution is determined by the sample geometry. Due to the boundary conditions at the sample borders, the current distribution in samples of arbitrary shape splits up into domains of nearly uniform parallel current flow which are separated by current domain boundaries, where the current streamlines are sharply bent. Qualitatively, the current pattern is described by the Bean model; however, changes due to a spatially dependent electric field distribution which is induced by flux creep or flux flow have to be taken into account. For small magnetic fields, the Meissner phase coexists with pinned vortex phases and the geometry-dependent Meissner screening currents contribute to the observed current patterns. The influence of additional factors on the current domain patterns are systematically analysed: local magnetic field dependence of j c (B), current anisotropy, inhomogeneities and local transport properties of grain boundaries. We then continue to an overview of the current distribution and current-limiting factors of materials, relevant to technical applications like melt-textured samples, coated conductors and tapes. Finally, a selection of magneto-optical experiments which give direct insight into vortex pinning and depinning mechanisms are reviewed.

show abstract

Section: Bi-2212 and Bi-2223 Tapesmentioning

confidence: 90%

Magneto-optical studies of current distributions in high-T_csuperconductors

et al. 2002

View full text Add to dashboard Cite

show abstract

“…Another report states that after mechanical loading, the E-I characteristic in the electric field range of 10 À6 -10 À9 V/cm changes notably, whereas that in the electric field range of 10 À3 -10 À6 V/cm remains unchanged for mono-core tapes [10,11]. It has also been reported that in the magnetization I c measurements where the magnetization is measured under much lower electric fields than the electric fields assumed in the definition of the I c in the transport measurements, the magnetization I c is more sensitive to small strains than the transport I c [5,9]. These reports indicate that the transport I c values of bent samples depend strongly on the electric field criterion used.…”

Section: Effects Of Bending Strain On the I C Criterionmentioning

confidence: 97%

“…Bending strain occurs in superconducting wires or tapes when they are transferred from a drum to another drum or wound in a coil shape for magnet construction. The bending strain effect on I c values has been studied widely in view of both basic and practical points [1][2][3][4][5]. However, in these studies, experimental conditions such as the bending method, the sample mounting method for I c measurement and the bending sequence of samples and I c measurements vary from laboratory to laboratory.…”

Section: Introductionmentioning

confidence: 99%

Bending strain effect on critical current of Bi-2223 superconductor tapes—report of international round-robin-test

Kuroda

Itoh

Katagiri

et al. 2005

Physica C: Superconductivity

View full text Add to dashboard Cite

“…Many micro-structural studies indicate that Bi-2223/Ag tapes in products contain some voids, secondary phases, and other defects that are likely to be stress concentration sites. Cai et al reported that extensive cracks exist in Bi-2223 oxide filaments of tapes before applying stress using a magneto-optical imaging technique [16][17][18]. These pre-existing cracks are probably remnants of the rolling process and heat treatment in the tape-manufacturing process.…”

Section: Comparison Of Critical Current Value Versus Strain Character...mentioning

confidence: 99%

Influence of test methods on critical current degradation of Bi-2223/Ag superconductor tapes by bending strain

Kuroda

Katagiri

Shin

et al. 2005

Supercond. Sci. Technol.

View full text Add to dashboard Cite

The results of two test methods were compared among three laboratories to determine a standard measurement method of critical current (Ic) as a function of bending strain for Ag-sheathed Bi-2223 superconductors. The VAMAS round-robin-test method (RRT) and the bending-rig method developed by Goldacker were used. The Ic degradation started with less bending strain for RRT than for bending-rig. Average irreversible strains (εirr) were 0.30% for RRT and 0.37% for bending-rig. Another test identified parameters that affected the results. A modified RRT method, with a current connection between the sample and the electrode, was used to avoid some thermal stresses of the test procedure. The εirr values increased to the level of the bending-rig, but the modified RRT Ic degradation rate with bending strain was higher. The stress states during sample bending differed between these methods. The shear stress was examined as a source of the Ic degradation rate differences with strain in terms of the crack propagation and delamination defects of oxide filaments from the Ag sheath.

show abstract

The Influence of Pre-Existing Defects on the Bending Strain Behavior of Bi2Sr2Ca1Cu2Ox and (Bi,Pb)2Sr2Ca2Cu3Ox Ag-Sheathed Tapes

Cited by 4 publications

References 10 publications

Magneto-optical studies of current distributions in high-T_csuperconductors

Magneto-optical studies of current distributions in high-T_csuperconductors

Bending strain effect on critical current of Bi-2223 superconductor tapes—report of international round-robin-test

Influence of test methods on critical current degradation of Bi-2223/Ag superconductor tapes by bending strain

Contact Info

Product

Resources

About

The Influence of Pre-Existing Defects on the Bending Strain Behavior of Bi2Sr2Ca1Cu2Ox and (Bi,Pb)2Sr2Ca2Cu3Ox Ag-Sheathed Tapes

Cited by 4 publications

References 10 publications

Magneto-optical studies of current distributions in high-Tcsuperconductors

Magneto-optical studies of current distributions in high-Tcsuperconductors

Bending strain effect on critical current of Bi-2223 superconductor tapes—report of international round-robin-test

Influence of test methods on critical current degradation of Bi-2223/Ag superconductor tapes by bending strain

Contact Info

Product

Resources

About

Magneto-optical studies of current distributions in high-T_csuperconductors

Magneto-optical studies of current distributions in high-T_csuperconductors