Assessing composition gradients in multifilamentary superconductors by means of magnetometry methods

Baumgartner, T.; Hecher, J; Bernardi, Johannes; Pfeiffer, Stephan; Senatore, Carmine; Eisterer, M.

doi:10.1088/0953-2048/30/1/014011

Cited by 8 publications

(7 citation statements)

References 17 publications

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“…Various experiments 11 – 13 and models 14 , 15 have recently been conducted to investigate the dependence of the superconductivity and magnetic properties of Nb 3 Sn samples on Sn content and disorder. The underlying physics for the superconducting properties variation with the A15 composition in Nb 3 Sn is however still not very clear.…”

Section: Introductionmentioning

confidence: 99%

GLAG theory for superconducting property variations with A15 composition in Nb3Sn wires

Gao

2017

Sci Rep

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We present a model for the variation of the upper critical field H c2 with Sn content in A15-type Nb-Sn wires, within the Ginzburg-Landau-Abrikosov-Gor’kov (GLAG) theory frame. H c2 at the vicinity of the critical temperature T c is related quantitatively to the electrical resistivity ρ, specific heat capacity coefficient γ and T c. H c2 versus tin content is theoretically formulated within the GLAG theory, and generally reproduces the experiment results. As Sn content gradually approaches the stoichiometry, A15-type Nb-Sn undergoes a transition from the dirty limit to clean limit, split by the phase transformation boundary. The H-T phase boundary and pinning force show different behaviors in the cubic and tetragonal phase. We dipict the dependence of the composition gradient on the superconducting properties variation in the A15 layer, as well as the curved tail at vicinity of H c2 in the Kramer plot of the Nb3Sn wire. This helps understanding of the inhomogeneous-composition inducing discrepancy between the results by the state-of-art scaling laws and experiments.

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Section: Introductionmentioning

confidence: 99%

GLAG theory for superconducting property variations with A15 composition in Nb3Sn wires

Gao

2017

Sci Rep

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“…introduced by Baumgartner et al [15], where ρ o and ρ i are the outer and inner radii of the single A-15 hollow cylinder respectively, N is the number of filaments and L their length. The measurements were repeated with three contiguous (4 mm) pieces of each wire in order to unmask any possible longitudinal inhomogeneities throughout the wire itself (e.g.…”

Section: Jc and B C2mentioning

confidence: 99%

“…The critical temperature T c of each sample was assessed as being the midpoint value of the superconducting to normal transition in the susceptibility curves (table 1). From these data and numerical simulations the volume Meissner shielding fraction was evaluated as described in [15]: all sub-elements were assumed to be identical parallel tubes with same geometry, composition and radial Sn gradient (with the highest value on the inside). Scans of the magnetic field in the Meissner state recorded at increasing temperature via SHPM rely on less assumptions: the information is local (subelement-per-subelement) and the evaluation of the shielding radii(T) does not need an iterative simulation as for the AC-susceptibility.…”

Section: Radial Inhomogeneitiesmentioning

confidence: 99%

Evolution of the superconducting properties from binary to ternary APC-Nb₃Sn wires

Ortino

Pfeiffer

Baumgartner

et al. 2021

Supercond. Sci. Technol.

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We present a study conducted on binary Tube Type and ternary powder-in-tube Nb3Sn wires manufactured using the artificial pinning centres-internal oxidation method. All the specimens are doped with Zr: oxide nano-particles of this element are responsible for the pinning improvement, both by refining the A-15 grain-size and their own point-pinning contribution. Low-field J c magnetometry confirms that the hadron-hadron Future Circular Collider (FCC-hh) specifications are met by one ternary doped-sample. The differences in microstructure were assessed by scanning electron microscopy/transmission electron microscopy to clarify the reasons for the pinning improvement between the two generations. The deviations from the Dew Hughes model are also discussed, underlying some non-linear addition due to competition between the two pinning mechanisms. Finally, we show how the introduction of Ta as a ternary addition influences the A-15 phase by focusing on the radial inhomogeneities, evaluating the T c distribution and Sn composition gradients. The latter are used to model the currents, enabling us to evaluate the individual weights of the pinning mechanisms and their absolute contributions at the High Luminosity-Large Hadron Collider and FCC-hh dipoles operational points.

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“…Reports of a discrepancy between the Tc distributions of Nb3Sn wires obtained from calorimetry and magnetometry [9] led to the conjecture that intra-granular Sn concentration gradients must also exist. This has been confirmed by transmission electron microscope (TEM) EDX analysis.…”

Section: A Analysis Of Tin Gradients and Non-uniformity In State Of mentioning

confidence: 99%

The CERN FCC Conductor Development Program: A Worldwide Effort for the Future Generation of High-Field Magnets

Ballarino

Hopkins

Bordini

et al. 2019

IEEE Trans. Appl. Supercond.

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The study of next generation high energy accelerators based on 16 T dipoles has emphasized the need for higher performance, cost-effective Nb3Sn superconducting wires. A Conductor Development Program aiming to reach a non-copper critical current density (Jc) of 1500 A/mm 2 at 16 T and 4.2 K has been launched by CERN, with the involvement of industry and laboratories worldwide. In this article, the targets and strategy of the program are presented, with an overview of the wire layouts and development activities being pursued by each partner, and the latest characterization results are reported. Three of the four participating manufacturers have successfully reached the first stage Jc milestone, but a significant advance is still needed to achieve the final target. The next steps are briefly discussed, as the program focuses increasingly on novel alloys and methods to maximize Jc.

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Assessing composition gradients in multifilamentary superconductors by means of magnetometry methods

Cited by 8 publications

References 17 publications

GLAG theory for superconducting property variations with A15 composition in Nb3Sn wires

GLAG theory for superconducting property variations with A15 composition in Nb3Sn wires

Evolution of the superconducting properties from binary to ternary APC-Nb₃Sn wires

The CERN FCC Conductor Development Program: A Worldwide Effort for the Future Generation of High-Field Magnets

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Assessing composition gradients in multifilamentary superconductors by means of magnetometry methods

Cited by 8 publications

References 17 publications

GLAG theory for superconducting property variations with A15 composition in Nb3Sn wires

GLAG theory for superconducting property variations with A15 composition in Nb3Sn wires

Evolution of the superconducting properties from binary to ternary APC-Nb3Sn wires

The CERN FCC Conductor Development Program: A Worldwide Effort for the Future Generation of High-Field Magnets

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Product

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Evolution of the superconducting properties from binary to ternary APC-Nb₃Sn wires