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Critical current density of superconducting-normal-superconducting Josephson junctions and polycrystalline superconductors in high magnetic fields (2022)
Journal Article
Blair, A., & Hampshire, D. (2022). Critical current density of superconducting-normal-superconducting Josephson junctions and polycrystalline superconductors in high magnetic fields. Physical Review Research, 4(2), Article 023123. https://doi.org/10.1103/physrevresearch.4.023123

We investigate the in-field critical current density Jc (B) of superconducting-normal-superconducting (SNS) Josephson junctions (JJs) and polycrystalline superconducting systems with grain boundaries modeled as Josephson-type planar defects, both ana... Read More about Critical current density of superconducting-normal-superconducting Josephson junctions and polycrystalline superconductors in high magnetic fields.

Critical Current Densities through Josephson Junctions in Low Magnetic Fields (2022)
Journal Article
Din, B., Blair, A., Schoofs, F., & Hampshire, D. (2022). Critical Current Densities through Josephson Junctions in Low Magnetic Fields. IEEE Transactions on Applied Superconductivity, 32(4), Article 8000805. https://doi.org/10.1109/tasc.2022.3156908

Understanding the properties of grain boundaries in polycrystalline superconductors is essential for optimizing their critical current density. Here, we provide computational simulations of 2D Josephson junctions (JJs) in low magnetic fields using ti... Read More about Critical Current Densities through Josephson Junctions in Low Magnetic Fields.

Computational Simulations Using Time-Dependent Ginzburg–Landau Theory for Nb–Ti-Like Microstructures (2022)
Journal Article
Haddon, C., Blair, A., Schoofs, F., & Hampshire, D. (2022). Computational Simulations Using Time-Dependent Ginzburg–Landau Theory for Nb–Ti-Like Microstructures. IEEE Transactions on Applied Superconductivity, 32(4), Article 8800105. https://doi.org/10.1109/tasc.2022.3156916

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, wit... Read More about Computational Simulations Using Time-Dependent Ginzburg–Landau Theory for Nb–Ti-Like Microstructures.

Self-Field Effects in a Josephson Junction Model for Jc in REBCO Tapes (2021)
Journal Article
Gurnham, C., & Hampshire, D. (2022). Self-Field Effects in a Josephson Junction Model for Jc in REBCO Tapes. IEEE Transactions on Applied Superconductivity, 32(4), Article 8000205. https://doi.org/10.1109/tasc.2021.3132858

We have modeled the effects of self-field on the critical current density Jc in high temperature superconducting REBCO tapes, by considering them as a collection of Josephson junctions (JJs) in parallel. We have used a 2D JJ framework for each juncti... Read More about Self-Field Effects in a Josephson Junction Model for Jc in REBCO Tapes.

Weak emergence in the angular dependence of the critical current density of the high temperature superconductor coated conductor REBCO (2020)
Journal Article
Branch, P., Osamura, K., & Hampshire, D. (2020). Weak emergence in the angular dependence of the critical current density of the high temperature superconductor coated conductor REBCO. Superconductor Science and Technology, 33(10), Article 104006. https://doi.org/10.1088/1361-6668/abaebe

Extensive critical current density Jc measurements are reported as a function of magnetic field B, temperature T, angle θ between the applied field and the surface of the tape, and strain ε, on a REBCO coated conductor. The strain, εpeak (B,T, θ), at... Read More about Weak emergence in the angular dependence of the critical current density of the high temperature superconductor coated conductor REBCO.

Successful production of solution blow spun YBCO+Ag complex ceramics (2020)
Journal Article
Pessoa, A., Raine, M., Hampshire, D., Namburi, D., Durrell, J., & Zadorosny, R. (2020). Successful production of solution blow spun YBCO+Ag complex ceramics. Ceramics International, 46(15), 24097-24101. https://doi.org/10.1016/j.ceramint.2020.06.188

YBCO fabrics composed of nanowires, produced by solution blow spinning (SBS) are so brittle that the Lorentz force produced by induced currents can be strong enough to damage them. On the other hand, it is known that silver addition improves the mech... Read More about Successful production of solution blow spun YBCO+Ag complex ceramics.

Angular Jc measurements at 77 K in-field, on an ISD REBCO coated conductor using a straightforward mechanical scribing technique to reduce tape width (2020)
Journal Article
Gurnham, C., Große, V., & Hampshire, D. (2020). Angular Jc measurements at 77 K in-field, on an ISD REBCO coated conductor using a straightforward mechanical scribing technique to reduce tape width. Journal of Physics: Conference Series, 1559, Article 012036. https://doi.org/10.1088/1742-6596/1559/1/012036

E-J traces have been measured on an inclined substrate deposition coated conductor up to 0.7 T as a function of angle at 77K. A large change in Jc is seen on reversal of the direction of the magnetic field, associated with different surface barriers... Read More about Angular Jc measurements at 77 K in-field, on an ISD REBCO coated conductor using a straightforward mechanical scribing technique to reduce tape width.

The magnetic field, temperature, strain and angular dependence of the critical current density for Nb-Ti (2020)
Journal Article
Chislett-Mcdonald, S., Tsui, Y., Surrey, E., Kovari, M., & Hampshire, D. (2020). The magnetic field, temperature, strain and angular dependence of the critical current density for Nb-Ti. Journal of Physics: Conference Series, 1559, Article 012063. https://doi.org/10.1088/1742-6596/1559/1/012063

A scaling law for Jc in commercial Nb-Ti wire is proposed that describes its magnetic field, temperature and strain dependence. The scaling law is used to fit extensive measurements of the total strand critical current density, Jc,TS(B, T, ε), with t... Read More about The magnetic field, temperature, strain and angular dependence of the critical current density for Nb-Ti.

Weakly-Emergent Strain-Dependent Properties of High Field Superconductors (2019)
Journal Article
Branch, P., Tsui, Y., Osamura, K., & Hampshire, D. (2019). Weakly-Emergent Strain-Dependent Properties of High Field Superconductors. Scientific Reports, 9, Article 13998. https://doi.org/10.1038/s41598-019-50266-1

All superconductors in high field magnets operating above 12 T are brittle and subjected to large strains because of the differential thermal contraction between component parts on cool-down and the large Lorentz forces produced in operation. The con... Read More about Weakly-Emergent Strain-Dependent Properties of High Field Superconductors.

Inverted-parabolic and weak strain dependencies on the critical current in practical <110> and <100> oriented REBCO tapes (2019)
Journal Article
Osamura, K., Machiya, S., Kajiwara, K., Kawasaki, T., Harjo, S., Zhang, Y., …Hampshire, D. P. (2019). Inverted-parabolic and weak strain dependencies on the critical current in practical and oriented REBCO tapes. AIP Advances, 9(7), Article 075216. https://doi.org/10.1063/1.5092248

In the commercial coated conductor tapes, the twinned structure of REBCO (REBa2Cu3O7-d, RE = Y and Gd) is characterized as either <100> or <110> orientation based on the tape length direction. In this study, we investigate the effects of the two diff... Read More about Inverted-parabolic and weak strain dependencies on the critical current in practical <110> and <100> oriented REBCO tapes.

A derivation of Maxwell’s equations using the Heaviside notation (2018)
Journal Article
Hampshire, D. (2018). A derivation of Maxwell’s equations using the Heaviside notation. Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences, 367(2134), Article 20170447. https://doi.org/10.1098/rsta.2017.0447

Maxwell's four differential equations describing electromagnetism are among the most famous equations in science. Feynman said that they provide four of the seven fundamental laws of classical physics. In this paper, we derive Maxwell's equations usi... Read More about A derivation of Maxwell’s equations using the Heaviside notation.

Self-field Effects on JC(B,T) Measurements of Nb-Ti Strands in High Magnetic Fields (2018)
Journal Article
Ridgeon, F., Raine, M., Lakrimi, M., Thomas, A., Boutboul, T., & Hampshire, D. (2018). Self-field Effects on JC(B,T) Measurements of Nb-Ti Strands in High Magnetic Fields. IEEE Transactions on Applied Superconductivity, 28(4), Article 9001805. https://doi.org/10.1109/tasc.2018.2808370

We have investigated the applied magnetic field, temperature, and self-field dependence of the critical current density of a Nb-Ti strand produced for the ITER Poloidal Field conductor. Measurements were made on a standard ITER barrel in magnetic fie... Read More about Self-field Effects on JC(B,T) Measurements of Nb-Ti Strands in High Magnetic Fields.

The Cause of ‘Weak-Link’ Grain Boundary Behaviour in Polycrystalline Bi2Sr2CaCu2O8 and Bi2Sr2Ca2Cu3O10 Superconductors (2018)
Journal Article
Wang, G., Raine, M. J., & Hampshire, D. P. (2018). The Cause of ‘Weak-Link’ Grain Boundary Behaviour in Polycrystalline Bi2Sr2CaCu2O8 and Bi2Sr2Ca2Cu3O10 Superconductors. Superconductor Science and Technology, 31(2), Article 024001. https://doi.org/10.1088/1361-6668/aaa1b8

The detrimental effects of grain boundaries have long been considered responsible for the low critical current densities (J_c) in high temperature superconductors. In this paper, we apply the quantitative approach used to identify the cause of the 'w... Read More about The Cause of ‘Weak-Link’ Grain Boundary Behaviour in Polycrystalline Bi2Sr2CaCu2O8 and Bi2Sr2Ca2Cu3O10 Superconductors.

Biaxial Strain Measurements of Jc on a (RE)BCO Coated Conductor (2018)
Journal Article
Greenwood, J. R., Surrey, E., & Hampshire, D. P. (2018). Biaxial Strain Measurements of Jc on a (RE)BCO Coated Conductor. IEEE Transactions on Applied Superconductivity, 28(4), Article 8400705. https://doi.org/10.1109/tasc.2018.2793282

For several years it has been possible to measure the uniaxial strain dependence of the critical current density JC (ε) of (RE)BCO coated conductors [(RE)BCO tapes] and a parabolic strain dependence of JC (ε) has been observed. To improve our underst... Read More about Biaxial Strain Measurements of Jc on a (RE)BCO Coated Conductor.

How Resistive Must Grain Boundaries in Polycrystalline Superconductors be, to Limit J_c? (2017)
Journal Article
Wang, G., Raine, M. J., & Hampshire, D. P. (2017). How Resistive Must Grain Boundaries in Polycrystalline Superconductors be, to Limit J_c?. Superconductor Science and Technology, 13(10), Article 104001. https://doi.org/10.1088/1361-6668/aa7f24

Although we can use misorientation angle to distinguish the grain boundaries that can carry high critical current density (J_c) in high temperature superconductors (HTS) from those that cannot, there is no established normal state property equivalent... Read More about How Resistive Must Grain Boundaries in Polycrystalline Superconductors be, to Limit J_c?.

Superconducting Properties of Titanium alloys (Ti-64 and Ti-6242) for critical current barrels (2016)
Journal Article
Ridgeon, F., Raine, M., Halliday, D., Lakrimi, M., Thomas, A., & Hampshire, D. (2017). Superconducting Properties of Titanium alloys (Ti-64 and Ti-6242) for critical current barrels. IEEE Transactions on Applied Superconductivity, 27(4), Article 4201205. https://doi.org/10.1109/tasc.2016.2645378

We have measured the superconducting properties of the titanium alloy Ti-6Al-4V (Ti-64) as-supplied and following two of the heat treatment schedules used for the Nb3Sn strands in the ITER tokamak. The Ti-64 alloy is the standard choice in the superc... Read More about Superconducting Properties of Titanium alloys (Ti-64 and Ti-6242) for critical current barrels.

Soldered joints—an essential component of demountable high temperature superconducting fusion magnets (2016)
Journal Article
Tsui, Y., Surrey, E., & Hampshire, D. (2016). Soldered joints—an essential component of demountable high temperature superconducting fusion magnets. Superconductor Science and Technology, 29(7), Article 075005. https://doi.org/10.1088/0953-2048/29/7/075005

Demountable superconducting magnet coils would offer significant benefits to commercial nuclear fusion power plants. Whether large pressed joints or large soldered joints provide the solution for demountable fusion magnets, a critical component or bu... Read More about Soldered joints—an essential component of demountable high temperature superconducting fusion magnets.

Mechanism for the uniaxial strain dependence of the critical current in practical REBCO tapes (2016)
Journal Article
Osamura, K., Machiya, S., & Hampshire, D. (2016). Mechanism for the uniaxial strain dependence of the critical current in practical REBCO tapes. Superconductor Science and Technology, 29(6), Article 065019. https://doi.org/10.1088/0953-2048/29/6/065019

In order to elucidate the effect of uniaxial strain on the critical current of practical REBCO tapes (REBa2Cu3O7−d , RE = Y and Gd) fabricated by Superpower and SuNAM, two types of critical current measurements were carried out. In the first, the tap... Read More about Mechanism for the uniaxial strain dependence of the critical current in practical REBCO tapes.