Studies of the Strain-Dependent Properties of A15 Filamentary Conductors at Brookhaven National Laboratory

Luhman, T.; Welch, D. O.

doi:10.1007/978-1-4684-3887-1_13

Cited by 9 publications

(6 citation statements)

References 8 publications

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“…The nonlinearity of the compress region differs from that of the tension region. The neutral plane shifts toward the center of the bending curvature, since the neutral center is established by a force balance between the compression and tension regions, and the elastic-to-plastic transition occurs in the tension region before the compression region [28]. Therefore, the neutral plane shift of REBCO Inner is not the same as that of REBCO Outer, as seen in figure 9(c).…”

Section: Width-bending Strain Effects On the Critical Currentmentioning

confidence: 97%

Width-bending characteristic of REBCO HTS tape and flat-tape Rutherford-type cabling

Takayasu¹

2021

Supercond. Sci. Technol.

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The width-bending behaviors for a rare earth barium copper oxide (REBCO) high-temperature superconducting (HTS) tape have been investigated. It has been found experimentally that the width-bending strain of a Yttrium Barium Copper Oxide (YBCO) tape does not degrade the critical current as much as is expected from the axial strain. The critical current is not directly affected by the width-bending strain but by the axial strain, which the width-bending strain generates by the Poisson effect. Since Poisson’s ratio is about 0.3, the axial strain effective on the critical current is about 30% of the width-bending strain. Therefore, the width-bending strain of even 1.5% degrades the critical current by only 15% if the REBCO layer side is bent inward. However, the critical current degraded by more than 70% when the REBCO layer is outward. The width-bending effects on the critical current have been further examined, considering Poisson’s ratio changes and the neutral plane shift of the REBCO tape substrate. Those changes would occur when the material yields due to severe width-bending. Based on the width-bending of REBCO tapes, flat-tape Rutherford-type cabling is discussed. A REBCO Rutherford-type cable can provide various advantages, especially for narrow-tape cabling. The flat-tape Rutherford-type cable has better characteristics against an electromagnetic transverse Lorentz force. Furthermore, the tape length of the cable can be approximately the same as the cable length allowing for excellent tape usage. REBCO Rutherford-type cabling will be a promising high-current, high-field cabling method using thin substrate REBCO tapes. It will be useful for AC ramp-field and pulse-field applications with low AC losses and low shield currents. It notes that the filaments in the cable are symmetrically distributed in parallel. Therefore, each filament’s inductance is uniform, and a uniform current distribution among the filaments can be obtained.

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Section: Width-bending Strain Effects On the Critical Currentmentioning

confidence: 97%

Width-bending characteristic of REBCO HTS tape and flat-tape Rutherford-type cabling

Takayasu¹

2021

Supercond. Sci. Technol.

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“…Nb 3 Sn superconductor properties are highly dependent on the lattice distortion of the Nb 3 Sn. Nb 3 Sn is also well known as a brittle compound that easily fractures under tension [35]. After forming the cable from the strands it (and the conductor jacket) are then heat treated for a few hundred hours at about 650 °C to form the Nb 3 Sn compound [2].…”

Section: The Design Challengementioning

confidence: 99%

“…Theoretically, based on differential contraction coefficients, the filaments in a steel jacket would experience a strain of −0.83% which reduces the jc from the peak of the curve by a factor of about 3 [35] whereas for a Titanium jacket the value is around −0.25% (and the jc is within 20% of the maximum value). Even in the 1990s, we expected some reduction of the 0.83% for steel, due to the impact of cabling, the positive effect of operation tensile strain and the extension of the jacket by the cable, hence the choice (rather arbitrary) of −0.5%.…”

Section: Limitations Of Criteriamentioning

confidence: 99%

The use of Nb₃Sn in fusion: lessons learned from the ITER production including options for management of performance degradation

Mitchell

Breschi

Tronza

2020

Supercond. Sci. Technol.

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The overall 30 year Nb 3 Sn conductor program for ITER provides an unusual opportunity to look at the issues created by the application of novel Nb 3 Sn technology on a large scale. ITER design criteria have evolved to make use of the features of the industrialized material, exploiting advantages as well as managing the disadvantages. There are lessons from the successes and failures to be learned for the future application of very high current Nb 3 Sn strands in fusion and high energy physics. The behaviour of Nb 3 Sn strands in the large compound ITER conductors is still producing surprises after 25 years of development, industrial production and testing, with the Nb 3 Sn strain sensitivity and brittleness producing many more subtle design impacts than originally foreseen. The results now obtained at the end of the ITER production suggest that, as a novelty for Nb 3 Sn, there are options for conditioning the strands in the ITER conductors that can be applied during commissioning and which could reduce the impact of brittleness by as much as one third.

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“…Especially, it is well-known that the residual strain induced on the wire architecture deteriorates superconducting characteristics more greatly than the hydrostatic strain as it is often investigated from a physical standpoint [2]. However, the detailed mechanism of the strain effect for wires still remains unsettled.…”

Section: Introductionmentioning

confidence: 99%

Strain Gauge Method for Evaluating a Three-Dimensional Residual Strain State in ${\rm Nb}_{3}{\rm Sn}$ Wires

Watanabe

Oguro

Awaji

et al. 2010

IEEE Trans. Appl. Supercond.

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Concerning the strain effect of superconducting properties for Nb 3 Sn wires, it is necessary to investigate a three-dimensional strain state that Nb 3 Sn superconductors truly experience in the composite wire. However, it is very difficult for Nb 3 Sn wires to obtain the three-dimensional residual strain components experimentally. We adopted the strain gauge that is directly glued onto the 1 mm outer diameter Nb 3 Sn wire, in order to quantitatively measure the three-dimensional distortions. To evaluate axial and lateral distortions of the wire, strain gauges were set in both axial and lateral directions. This measurement system can obtain the distortion detail in fields up to 27 T at temperatures ranging from 4.2 to 20 K. We measured the upper critical field c2 in a three-dimensional strain state for Nb 3 Sn wires. It was found that the wire architecture changes each residual strain in axial and lateral directions of the wire. Moreover, the c2 strain sensitivity that is related to the c2 variation is also affected by its architecture. We found that the axial tensile strain variation 0.3% roughly corresponded to the lateral compressive strain variation 0.1% for Nb 3 Sn wires. This means that the ratio of the lateral strain and the axial one forNb 3 Sn wires is 0.3. The ratio of both residual strains in the axial and lateral directions is very important to examine the strain effect of Nb 3 Sn wires in detail.Index Terms-High magnetic field, Nb 3 Sn, stain effect, threedimensional distortion.

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Studies of the Strain-Dependent Properties of A15 Filamentary Conductors at Brookhaven National Laboratory

Cited by 9 publications

References 8 publications

Width-bending characteristic of REBCO HTS tape and flat-tape Rutherford-type cabling

Width-bending characteristic of REBCO HTS tape and flat-tape Rutherford-type cabling

The use of Nb₃Sn in fusion: lessons learned from the ITER production including options for management of performance degradation

Strain Gauge Method for Evaluating a Three-Dimensional Residual Strain State in ${\rm Nb}_{3}{\rm Sn}$ Wires

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Studies of the Strain-Dependent Properties of A15 Filamentary Conductors at Brookhaven National Laboratory

Cited by 9 publications

References 8 publications

Width-bending characteristic of REBCO HTS tape and flat-tape Rutherford-type cabling

Width-bending characteristic of REBCO HTS tape and flat-tape Rutherford-type cabling

The use of Nb3Sn in fusion: lessons learned from the ITER production including options for management of performance degradation

Strain Gauge Method for Evaluating a Three-Dimensional Residual Strain State in ${\rm Nb}_{3}{\rm Sn}$ Wires

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Product

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The use of Nb₃Sn in fusion: lessons learned from the ITER production including options for management of performance degradation