Charged Tangles of Quantized Vortices in Superfluid 4He

Golov, A. I.; Walmsley, P. M.; Tompsett, P. A.

doi:10.1007/s10909-010-0241-0

Cited by 10 publications

(7 citation statements)

References 53 publications

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“…We relate U to the total hydrodynamic impulse P through P ∼ ρD 3 U , where ρ = 145 kg m −3 is the density of helium. Before reaching the grid, each ion transfers to the fluid impulse eV * /v * (with v * ∼ 0.2 m s −1 being the mean velocity of ions dragged by electric field through the slower vortex tangle as a consequence of frequent reconnections when at T < 0.7 K [39,40]). The rate of transfer of impulse to the jet into the cell (see Fig.…”

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confidence: 99%

Coexistence of Quantum and Classical Flows in Quantum Turbulence in TheT=0Limit

Walmsley

Golov

2017

Phys. Rev. Lett.

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Tangles of a quantized vortex line of initial density L(0)∼6×10^{3} cm^{-2} and a variable amplitude of fluctuations of flow velocity U(0) at the largest length scale are generated in superfluid ^{4}He at T=0.17 K, and their free decay L(t) is measured. If U(0) is small, the excess random component of the vortex line length first decays as L∝t^{-1} until it becomes comparable with the structured component responsible for the classical velocity field, and the decay changes to L∝t^{-3/2}. The latter regime always ultimately prevails, provided the classical description of U holds. A quantitative model of coexisting cascades of quantum and classical energies describes all regimes of the decay.

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confidence: 99%

Coexistence of Quantum and Classical Flows in Quantum Turbulence in TheT=0Limit

Walmsley

Golov

2017

Phys. Rev. Lett.

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“…We suggest that a turbulent vortex tangle in the zero temperature limit can be thought of as a gas of solitons [23] and Kelvin waves on vortex lines interacting with a gas of vortex rings and phonons in the bulk-with frequent interconversion of rings to solitons and vice versa. Such features may eventually be observable using the visualization techniques currently being developed for the zero temperature limit or through experiments using charged ions trapped on vortices [25]. Fig.…”

Section: Discussionmentioning

confidence: 99%

Quantized Vortex Rings and Loop Solitons

et al. 2020

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The vortex filament model is used to investigate the interaction of a quantized vortex ring with a straight vortex line and also the interaction of two solitons traveling in opposite directions along a vortex. When a ring reconnects with a line, we find that a likely outcome is the formation of a loop soliton. When they collide, loop solitons reconnect as they overlap each other producing either one or two vortex rings. These simulations are relevant for experiments on quantum turbulence in the zero temperature limit where small vortex rings are expected to be numerous. It seems that loop solitons might also commonly occur on vortex lines as they act as transient states between the absorption of a vortex ring before another ring is emitted when the soliton is involved in a reconnection.

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“…Perhaps the best way for detecting them would be via Particle Tracking Velocimetry (PTV) techniques which employ small particles that do not easily escape superfluid vortices once they collide with them. Since there is significant experience with PTV methods in current superfluid research [40][41][42], the main difficulty to be encountered in such future experiments is the manipulation of the normalfluid vorticity into organized structures. Such an experimental breakthrough would bring superfluid hydrodynamics on par with more traditional fields in hydrodynamics, enabling a vigorous interaction between theory and experiment.…”

Section: Interactions Between Rings Of Similar Sizementioning

confidence: 99%

Superfluid helium-4 hydrodynamics with discrete topological defects

Kivotides

2018

Phys. Rev. Fluids

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In superfluid helium-4, a model of normal-fluid hydrodynamics and their coupling with topological defects (quantized vortices) of the order parameter (superfluid) is formulated. The model requires only material properties as input, and applies to both laminar and turbulent flows, to both dilute and dense superfluid vortex tangles. By solving the model for the case of a normal-fluid vorticity Hopf-link interacting with systems of quantized vortices, two vortex dynamical mechanisms of energy transfer from the normal-fluid to the superfluid are indicated: (a) small superfluid rings expand to the size of the normal-fluid vortex link tubes, and (b) superfluid rings with diameters similar to the diameters of the normal-fluid tubes succumb to axial-flow instabilities that excite small amplitude wiggles which subsequently evolve into spiral-waves along the superfluid vortex contours. The normal-fluid vorticity scale determines the upper size of the generated superfluid vorticity structures. A key role in energy transfer processes is played by an axial-flow instability of a superfluid vortex due to mutual-friction excitation by the normal-fluid, which mirrors the instability of normal-fluid tubes due to mutual-friction excitation by the superfluid. Although the sites of superfluid vorticity generation are always in the neighbourhood of intense normal-fluid vorticity events, the superfluid vortices do not mimic the normal-fluid vorticity structure, and perform different motions. These vortex dynamical processes provide explanations for the phenomenology of fully developed finite temperature superfluid turbulence. PROLOGUE Due to quantum decoherence and the loss of quantum interference effects [1, 2], the hydrodynamics of many quantum systems (e.g., quark-gluon plasmas [3] or helium-4 liquids above the critical temperature of T = 2.17 K) follow similar equations with those that apply to classical gases and liquids. In the helium-4 case however, below T = 2.17 K (the so-called lambda point), the global U (1) symmetry of the microscopic quantum system is spontaneously broken (Bose-Einstein Condensation), and low-frequency, long-wavelength Nambu-Goldstone modes appear, that need vanishingly little energy to excite, and are referred to as order-parameter dynamics [4]. These modes are of different nature than the (normal-fluid) hydrodynamics corresponding to conservation laws. Although spontaneous symmetry breaking is also a feature of classical systems (e.g., topological defect networks in liquid crystals: Poiseuille flow [5] or simple shear flow [6]), in helium-4, the broken symmetry corresponds to the conservation of particle number, and the corresponding order parameter obeys a nonlinear Schroedinger equation that depicts an inviscid, compressible superfluid populated with topological defects (vortices). In other words, the order parameter is a material field, a rather intriguing physics case. The term material field indicates that, rather than been (for example) a quality like the net magnetization in a ferromagnetic system...

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Charged Tangles of Quantized Vortices in Superfluid 4He

Cited by 10 publications

References 53 publications

Coexistence of Quantum and Classical Flows in Quantum Turbulence in TheT=0Limit

Coexistence of Quantum and Classical Flows in Quantum Turbulence in TheT=0Limit

Quantized Vortex Rings and Loop Solitons

Superfluid helium-4 hydrodynamics with discrete topological defects

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