Ultrasonically generated quantized vorticity in HeII

Carey, R. F.; Rooney, James A.; Smith, Charles W.

doi:10.1016/0375-9601(78)90713-2

Cited by 16 publications

(3 citation statements)

References 16 publications

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“…A novel form of quantum turbulence generation has been devised by Smith and his colleagues (Carey, Rooney & Smith 1978). Recent experiments (Schwarz & Smith 1981 ;Milliken, Schwarz & Smith 1982) have utilized the apparatus shown in figure 21.…”

Section: Ultrasonically Generated Turbulencementioning

confidence: 99%

Quantum turbulence

Donnelly

Swanson

1986

J. Fluid Mech.

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We present a review of quantum turbulence, that is, the turbulent motion of quantized vortex lines in superfluid helium. Our discussion concentrates on the turbulence produced by steady, uniform heat flow in a pipe, but touches on other turbulent flows as well. We have attempted to motivate the study of quantum turbulence and discuss briefly its connection with classical turbulence. We include background on the two-fluid model and mutual friction theory, examples of modern experimental techniques, and a brief survey of the phenomenology. We discuss the important recent insights that vortex dynamics has provided to the understanding of quantum turbulence, from simple scaling arguments to detailed numerical simulations. We conclude with a discussion of open questions in this field.

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Section: Ultrasonically Generated Turbulencementioning

confidence: 99%

Quantum turbulence

Donnelly

Swanson

1986

J. Fluid Mech.

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“…We show that vortex nucleation takes place in moving bubbles of even smaller radius if the motion made them sufficiently oblate. [6] by the collapse of cavitated bubbles [7] generated by ultrasound in the megahertz frequency range. The aim of this Letter is to analyse theoretically for the first time the physics of this process in the context of the GrossPitaevskii (GP) equation.…”

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confidence: 99%

“…Moving positive [2] and negative [3] ions were shown to generate vortex rings on their surface where the speed of sound was exceeded. Experiments in superfluid helium have demonstrated long time ago the production of quantised vortices and turbulence [6] by the collapse of cavitated bubbles [7] generated by ultrasound in the megahertz frequency range. The aim of this Letter is to analyse theoretically for the first time the physics of this process in the context of the Gross-Pitaevskii (GP) equation.…”

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confidence: 99%

Vortex Nucleation by Collapsing Bubbles in Bose-Einstein Condensates

Berloff¹,

Barenghi²

2004

Phys. Rev. Lett.

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The nucleation of vortex rings accompanies the collapse of ultrasound bubbles in superfluids. Using the Gross-Pitaevskii equation for a uniform condensate we elucidate the various stages of the collapse of a stationary spherically symmetric bubble and establish conditions necessary for vortex nucleation. The minimum radius of the stationary bubble, whose collapse leads to vortex nucleation, was found to be 28 ± 1 healing lengths. The time after which the nucleation becomes possible is determined as a function of bubble's radius. We show that vortex nucleation takes place in moving bubbles of even smaller radius if the motion made them sufficiently oblate. [6] by the collapse of cavitated bubbles [7] generated by ultrasound in the megahertz frequency range. The aim of this Letter is to analyse theoretically for the first time the physics of this process in the context of the GrossPitaevskii (GP) equation. Vortex nucleation by collapsing bubbles could also be studied in the context of (nonuniform) atomic condensates (BEC), for which the GP equation provides a quantitative model, thus providing experimentalists with a new mechanism to produce vortices in BEC systems, alongside rotation [8], the decay of solitons [9] and phase imprinting [10]. Moreover, our work illustrates a new aspect of vortex-sound interaction in a Bose-Einstein condensate, a topic which is receiving increasing attention [11].We write the GP equation in dimensionless form asin dimensionless variables such that the unit of length corresponds to the healing length ξ, the speed of sound is c = 1/ √ 2, and the density at infinity is ρ ∞ = |ψ ∞ | 2 = 1. To convert the dimensionless units into values applicable to superfluid helium-4, we take the number density as ρ = 2.18×10 28 m −3 , the quantum of circulation as κ = h/m = 9.92×10 −8 m 2 s −1 , and the healing length as ξ = 0.128nm. This gives a time unit 2πξ 2 /κ ∼ 1ps. Whereas for a sodium condensate with ξ ≈ 0.14µm, the time unit is about 8ns. V (x, t) is the potential of interaction between a boson and a bubble. We will assume that the bubble acts as an infinite potential barrier to the condensate, so that no bosons can be found inside the bubble (ψ = 0) before the collapse. This is achieved by setting V to be large inside the bubble and zero outside.First we consider the case of a stationary spherically symmetrical bubble. The spherical symmetry allows us to reduce the problem to dimension one, so that the equation (1) for ψ = ψ(r, t) becomeswhere r 2 = x 2 + y 2 + z 2 . Equation (2) is numerically integrated using fourth order finite differences discretization in space and fourth order Runge-Kutta method in time. Before the collapse the field around the bubble of radius a is stationary, ψ t = 0. The boundary conditions are ψ(a, t) = 0 stating that the bubble surface is an infinite potential barrier to the condensate and ψ(∞, t) = 1. The stationary solutions for various a were found by the Newton-Raphson iterations. The solutions are ψ(r) = (0, 0) if r ≤ a and ψ(r) = (R a (r), 0) if r > a, wit...

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Bose-Einstein condensation and superfluid turbulence

Berloff

2008

Vortices and Turbulence at Very Low Temperatures

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Ultrasonically generated quantized vorticity in HeII

Cited by 16 publications

References 16 publications

Quantum turbulence

Quantum turbulence

Vortex Nucleation by Collapsing Bubbles in Bose-Einstein Condensates

Bose-Einstein condensation and superfluid turbulence

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