Development of High Superconductor Fraction ${\hbox{Bi}}_{2}{\hbox{ Sr}}_{2}{\hbox{CaCu}}_{2}{\hbox{O}}_{\rm x}/{\hbox{Ag}}$ Wire for MRI

Nachtrab, W.T.; Renaud, C.V.; Wong, Terence Kin Shun; Liu, X.T.; Shen, Tengming; Trociewitz, U.P.; Schwartz, J.

doi:10.1109/tasc.2008.920630

Cited by 21 publications

(16 citation statements)

References 14 publications

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“…It has been already demonstrated that such properties make Bi-2212 a very competitive conductor for high field applications (> 20 T) such as magnets for nuclear magnetic resonance or accelerators [4][5][6][7][8][9], however, in this context, an enhancement of J C of two or three times seems to be still needed to boost the successful use of this superconductor in such applications. This aim has driven the work of several groups, especially in USA -where, besides the research labs, Oxford Superconducting Technology (OST) is a company leader on Bi-2212 round wire fabrication -and in Japan and Korea.…”

Section: Introductionmentioning

confidence: 99%

“…Over the last years the interest about Bi 2 Sr 2 CaCu 2 O x (Bi-2212) superconductor has been renewed thanks to its critical current density J C exceeding 10 5 A/cm 2 at 4.2 K, its irreversibility field over 100 T at the same temperature [1][2][3] and, maybe the most important, to its peculiar characteristic to be processed as round wire, unique within the family of the cuprate superconductors. It has been already demonstrated that such properties make Bi-2212 a very competitive conductor for high field applications (> 20 T) such as magnets for nuclear magnetic resonance or accelerators [4][5][6][7][8][9], however, in this context, an enhancement of J C of two or three times seems to be still needed to boost the successful use of this superconductor in such applications. This aim has driven the work of several groups, especially in USAwhere, besides the research labs, Oxford Superconducting Technology (OST) is a company leader on Bi-2212 round wire fabrication -and in Japan and Korea.…”

Section: Introductionmentioning

confidence: 99%

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Large critical current density improvement in Bi-2212 wires through the groove-rolling process

Malagoli¹,

Bernini²,

Braccini³

et al. 2013

Supercond. Sci. Technol.

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Recently the interest about Bi-2212 round wire superconductor for high magnetic field use has been enhancing despite the fact that an increase of the critical current is still needed to boost its successful use in such applications. Recent studies have demonstrated that the main obstacle to current flow, especially in long wires, is the residual porosity inside these Powder-In-Tube processed conductors which develops in bubbles-agglomeration when the Bi-2212 melts. Through this work we tried to overcome this issue acting on the wire densification by changing the deformation process. Here we show the effects of groove-rolling versus drawing process on the critical current density J C and on the microstructure. In particular, groove-rolled multifilamentary wires show a J C increased by a factor of about 3 with respect to drawn wires prepared with the same Bi-2212 powder and architecture. We think that this approach in the deformation process is able to produce the required improvements both because the superconducting properties are enhanced and because it makes the fabrication process faster and cheaper.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Large critical current density improvement in Bi-2212 wires through the groove-rolling process

Malagoli¹,

Bernini²,

Braccini³

et al. 2013

Supercond. Sci. Technol.

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“…Bi 2 Sr 2 CaCu 2 O x (Bi-2212) is the only cuprate superconductor that can be made into a round-wire conductor with a critical current density (J c ) over 10 5 A cm −2 at 4.2 K, and an irreversibility field (H irr (4.2 K)) greater than 100 T [1][2][3]. This makes Bi-2212 round wire unique and very competitive for high magnetic field (>20 T) applications, especially for nuclear magnetic resonance (NMR) magnets and for accelerators [4][5][6][7][8][9]. The crossover field with its nearest roundwire competitor, Nb 3 Sn, lies in the 18-20 T range.…”

Section: Introductionmentioning

confidence: 99%

Doubled critical current density in Bi-2212 round wires by reduction of the residual bubble density

Jiang¹,

Starch²,

Hannion³

et al. 2011

Supercond. Sci. Technol.

105

102

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We have recently shown that the gas present in the only ∼70% dense filaments of as-drawn Bi-2212 wire agglomerates into large bubbles that fill the entire filament diameter during the melt phase of the heat treatment. Once formed, these bubbles never disappear, although they can be bridged by 2212 grains formed on cooling. In order to test the effect of these bubbles on the critical current I c , we increased the density of the filaments after drawing using 2 GPa of cold isostatic pressure, finding that the bubble density and size were greatly reduced and that I c could be at least doubled. We conclude that enhancement of the filament packing density is of great importance for making major I c improvements in this very useful, round superconducting wire.

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“…Single restack powder-in-tube Bi2212/AgMg rectangular wire with an aspect ratio equal to two is provided by Supercon, Inc. [42]. The wire consists of 502 filaments with cross-sectional dimensions of 1.2 × 0.6 mm 2 and is shown in figure 2 in the as-drawn state (i.e.…”

Section: Experimental Approachmentioning

confidence: 99%

On the influence of magnetic field processing on the texture, phase assemblage and properties of low aspect ratio Bi₂Sr₂CaCu₂O_x/AgMg wire

Liu

Schwartz

2009

Science and Technology of Advanced Materials

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Bi 2 Sr 2 CaCu 2 O x /AgMg conductors are potentially important for many applications up to 20 K, including magnets for cryogen-free magnetic resonance imaging and high field nuclear magnetic resonance research. One promising approach to increased critical current density is partial-melt processing in the presence of a magnetic field which has been shown to enhance c-axis texturing of wide, thin tape conductors. Here, we report on low aspect ratio rectangular conductors processed in an 8 T magnetic field. The magnetic field is applied during different stages of the heat treatment process. The conductors are electrically characterized using four-point critical current measurements as a function of magnetic field and magnetic field orientation relative to the conductor. The superconductive transition and magnetization hysteresis are measured using a SQUID magnetometer. The microstructures are characterized using scanning electron microscopy and energy dispersive spectroscopy and analyzed using digital image processing. It is found that the presence of a magnetic field during split melt processing enhances the electrical transport and magnetic behavior, but that the anisotropy is not consistently affected. The magnetic field also affects development of interfilamentary Bi2212 bridges, and that this depends on the initial shape of the Bi2212 filament. At least two behaviors are identified; one impacts the oxide phase assemblage and the other impacts textured growth.

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Development of High Superconductor Fraction ${\hbox{Bi}}_{2}{\hbox{ Sr}}_{2}{\hbox{CaCu}}_{2}{\hbox{O}}_{\rm x}/{\hbox{Ag}}$ Wire for MRI

Cited by 21 publications

References 14 publications

Large critical current density improvement in Bi-2212 wires through the groove-rolling process

Large critical current density improvement in Bi-2212 wires through the groove-rolling process

Doubled critical current density in Bi-2212 round wires by reduction of the residual bubble density

On the influence of magnetic field processing on the texture, phase assemblage and properties of low aspect ratio Bi₂Sr₂CaCu₂O_x/AgMg wire

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Development of High Superconductor Fraction ${\hbox{Bi}}_{2}{\hbox{ Sr}}_{2}{\hbox{CaCu}}_{2}{\hbox{O}}_{\rm x}/{\hbox{Ag}}$ Wire for MRI

Cited by 21 publications

References 14 publications

Large critical current density improvement in Bi-2212 wires through the groove-rolling process

Large critical current density improvement in Bi-2212 wires through the groove-rolling process

Doubled critical current density in Bi-2212 round wires by reduction of the residual bubble density

On the influence of magnetic field processing on the texture, phase assemblage and properties of low aspect ratio Bi2Sr2CaCu2Ox/AgMg wire

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On the influence of magnetic field processing on the texture, phase assemblage and properties of low aspect ratio Bi₂Sr₂CaCu₂O_x/AgMg wire