Critical current density of superconducting-normal-superconducting Josephson junctions and polycrystalline superconductors in high magnetic fields

Blair, Alexander I.; Hampshire, D.P.

doi:10.1103/physrevresearch.4.023123

Cited by 5 publications

(2 citation statements)

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“…Grain boundary structures are of particular importance because most technological superconductors are polycrystalline and the grain boundary defects strongly affect magnetic flux distribution and limit J c [44,45]. The superconductivity group of Durham University has constructed a framework for analytical and computational the critical current of two-dimensional (2D) and three-dimensional (3D) polycrystalline systems with grain boundaries based on the time-dependent Ginzburg-Landau theory [46][47][48][49][50]. Within this framework, the flux pinning effect can be visualized and quantified, and the in-field J c can be simulated.…”

Section: Introductionmentioning

confidence: 99%

Numerical simulation of mechanical behaviors and intergranular fracture of polycrystalline Nb₃Sn and superconducting filaments

Ding

Marzi

Gao

2023

Supercond. Sci. Technol.

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Given the importance of large-scale engineering applications of the superconducting compound Nb3Sn, both its use and performance under certain operating conditions have attracted the interest of applied superconductivity researchers and material scientists for several years now. Huge efforts are directed toward understanding the response to applied loads and predicting fracture damage within their internal microstructure; this is fundamental in the design of superconducting coils and magnets which must meet stringent requirements in terms of maximum thermal and electromagnetic loads. In this paper, the fracture behaviors in polycrystalline Nb3Sn and Nb3Sn filaments with composite structures are investigated using the micromechanical finite element (FE) models with Voronoi tessellation. First, the 2D and 3D Voronoi FE models of the polycrystalline Nb3Sn tensile tests are developed and validated to provide insight into the cracking behavior in the intergranular brittle fracture of polycrystalline Nb3Sn. A cohesive zone model is used to simulate crack propagation at the grain level model including grain boundary zones. It is found that the pre-existing cracks of polycrystals and martensitic phase transformation of grains significantly impact the fracture properties in polycrystalline Nb3Sn. Second, detailed FE models of powder-in-tube (PIT) and bronze route (BR) filaments with Voronoi structures for fracture analysis are then developed on the basis of experimental observations of sectional morphologies. The mechanism of crack initiation and propagation under tensile load have been investigated by analyzing the mechanical properties of each component and the characteristics of multi-scale composite structures of filaments. Furthermore, the damage situation is investigated in PIT filaments undergoing transverse compressive load. The proposed simulation method in this paper can be extended to the fracture and damage analysis of Nb3Sn superconducting wires with different layouts and fabrication processes.

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Section: Introductionmentioning

confidence: 99%

Numerical simulation of mechanical behaviors and intergranular fracture of polycrystalline Nb₃Sn and superconducting filaments

Ding

Marzi

Gao

2023

Supercond. Sci. Technol.

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“…A standard search strategy [19] for the critical current density starts with the applied current density at an initial value J ext which is substantially greater than the critical current [20]. The applied current is then exponentially reduced in steps until J c is found.…”

Section: B Determining the Critical Current Densitymentioning

confidence: 99%

Computational Simulations Using Time-Dependent Ginzburg–Landau Theory for Nb–Ti-Like Microstructures

Haddon

Blair

Schoofs

et al. 2022

IEEE Trans. Appl. Supercond.

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Simulations based on time-dependent Ginzburg-Landau theory are employed to determine the critical current for a model system which represents a Nb-Ti-like pinning landscape at low drawing strain. The system consists of ellipsoids of normal metal, with dimensions 60ξ × 3ξ × 3ξ, randomly distributed throughout the superconducting bulk with their long axes parallel to the applied current and perpendicular to the field. These preciptates represent the α α α-Ti elongated precipitates which act as strong pinning centres in Nb-Ti alloys. We present the volume pinning force density as a function of field across the entire range of precipitate volume fractions and find that optimised material in our model system occurs at 32 vol.% ppt., whereas in real materials the optimum occurs at 25 vol.% ppt. The maximum pinning force density in our simulations is slightly higher (5.4 × 10 −3 JDBc2 vs. 17 GN•m −3 = 4.5 × 10 −3 JDBc2) and occurs at a lower reduced field (0.2Bc2 vs. 0.5Bc2) than in real materials. We conclude that the broad features of Nb-Ti-like systems are captured in our model, but that the details of the precipitate pinning mechanism are not yet included properly.

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Insulating nanoparticle induced pinning in YBCO superconductor: crossover from collective to strong pinning regimes

Mandal,

Rakshit,

et al. 2023

Appl. Phys. A

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Critical current density of superconducting-normal-superconducting Josephson junctions and polycrystalline superconductors in high magnetic fields

Cited by 5 publications

References 60 publications

Numerical simulation of mechanical behaviors and intergranular fracture of polycrystalline Nb₃Sn and superconducting filaments

Numerical simulation of mechanical behaviors and intergranular fracture of polycrystalline Nb₃Sn and superconducting filaments

Computational Simulations Using Time-Dependent Ginzburg–Landau Theory for Nb–Ti-Like Microstructures

Insulating nanoparticle induced pinning in YBCO superconductor: crossover from collective to strong pinning regimes

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Critical current density of superconducting-normal-superconducting Josephson junctions and polycrystalline superconductors in high magnetic fields

Cited by 5 publications

References 60 publications

Numerical simulation of mechanical behaviors and intergranular fracture of polycrystalline Nb3Sn and superconducting filaments

Numerical simulation of mechanical behaviors and intergranular fracture of polycrystalline Nb3Sn and superconducting filaments

Computational Simulations Using Time-Dependent Ginzburg–Landau Theory for Nb–Ti-Like Microstructures

Insulating nanoparticle induced pinning in YBCO superconductor: crossover from collective to strong pinning regimes

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Numerical simulation of mechanical behaviors and intergranular fracture of polycrystalline Nb₃Sn and superconducting filaments

Numerical simulation of mechanical behaviors and intergranular fracture of polycrystalline Nb₃Sn and superconducting filaments