Behavior of quartz forks oscillating in isotopically pure<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:msup><mml:mrow /><mml:mn>4</mml:mn></mml:msup></mml:math>He in the<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>T</mml:mi></mml:math><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mo>→</mml:mo></mml:math>0 limit

Garg, Deepak; Ефимов, В. М.; Giltrow, M.; McClintock, Peter V. E.; Skrbek, L.; Vinen, W. F.

doi:10.1103/physrevb.85.144518

Cited by 35 publications

(29 citation statements)

References 30 publications

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“…The transition between the two limits is generally rather smooth. In the quantum case, there seems to be a critical velocity above which the drag coefficient undergoes a large increase, rather sharply at low temperatures, tending again at the highest velocities to what may be a constant value; this constant value can be of order unity, but often it seems to be significantly smaller, especially at low temperatures, where there is little normal fluid and where therefore the drag at low velocities is very small (10). Again, the details may be more complicated.…”

Section: Superfluid Helium | Quantized Vortex Linesmentioning

confidence: 99%

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Quantum turbulence generated by oscillating structures

Vinen

Skrbek

2014

Proc. Natl. Acad. Sci. U.S.A.

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The paper summarizes important aspects of quantum turbulence that have been studied successfully with oscillating structures. It describes why some aspects are proving hard to interpret, and it outlines the need for new types of experiment and new developments in theoretical and computational work. superfluid helium | quantized vortex linesThis paper is concerned with the generation of quantum turbulence (1-3) in liquid helium by various forms of oscillating structure, such as a cylinder oscillating in a direction normal to its length. Many experiments on the generation of quantum turbulence by such structures have been reported, involving not only cylinders (or wires), but also spheres, tuning forks, and grids. Many of these experiments and their possible interpretation have already been reviewed (4). We are not aiming to produce another conventional review, and we shall not consider all that has been achieved. Instead, our aim is to focus on three particular aspects of this type of work: first, on experiments that have already contributed significantly to our understanding of issues that are, as we see them, of general and fundamental importance; second, on an exposure of the difficulties in interpreting many of the experiments in any real detail, in the way that has been achieved in analogous work on classical fluids; and third, on ways in which we might overcome these difficulties, which are both theoretical and experimental. We shall be concerned ultimately with both superfluid He. There are of course connections between quantum turbulence produced by oscillating structures and more general aspects of such turbulence. The role of remanent vorticity in the nucleation and stability of quantum turbulence is universally important, and, as we discuss in a later section, it is here that experiments with oscillating structures have been particularly instructive. At a more subtle level, there is the question of the extent to which quantum turbulence is similar to classical turbulence. The observation of a Kolmogorov energy spectrum on large length scales (larger than the vortex-line spacing) in homogeneous quantum turbulence is often quoted as evidence for this similarity. As we shall see, some aspects of the quantum turbulence produced by oscillating structures provide additional evidence. However, in contrast to homogeneous turbulence, quantum turbulence produced by an oscillating structure must be strongly influenced by the boundary conditions at a solid wall. As we discuss in a section devoted to the development of quantum turbulence, uncertainty about the boundary conditions relevant to quantum turbulence hinders interpretation of the experiments and calls for renewed experimental and theoretical study.Almost all of the experiments have involved measurements of the fluid dynamical force on the structure as a function of the amplitude of the oscillations. This force can be divided into a drag, which is in phase with the velocity and therefore dissipative, and a force that is in quadrature with the velocity and ...

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Section: Superfluid Helium | Quantized Vortex Linesmentioning

confidence: 99%

“…Again, the details may be more complicated. It seems that sometimes there are two critical velocities (5,10,11), especially at low temperatures, the drag increasing only a little at the lower value (Fig. 1, bottom curve).…”

Section: Superfluid Helium | Quantized Vortex Linesmentioning

confidence: 99%

Quantum turbulence generated by oscillating structures

Vinen

Skrbek

2014

Proc. Natl. Acad. Sci. U.S.A.

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“…On the other hand, we have not observed any sign of such e ects as seen in Ref. 22 around their v c1 , notably the increase or suppression of the drag depending on whether the original value of the drag was high or low (as in uenced by coupling to acoustic modes) with our 6.5 kHz tuning fork. As this fork was designed and chosen with special considerations for minimizing its acoustic emission, it seems that the e ects observed in Ref.…”

Section: Methodsmentioning

confidence: 75%

“…As this fork was designed and chosen with special considerations for minimizing its acoustic emission, it seems that the e ects observed in Ref. 22 might be related to acoustics phenomena. Indeed, the 55.5 kHz fork that is expected to have a measurable acoustic drag shows such an increase in the drag force (Fig.…”

Section: Methodsmentioning

confidence: 99%

Multiple critical velocities in oscillatory flow of superfluidHe4due to quartz tuning forks

et al. 2016

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We report recent investigations into the transition to turbulence in super uid 4 He, realized experimentally by measuring the drag forces acting on two custom-made quartz tuning forks with fundamental resonances at 6.5 kHz and 55.5 kHz, in the temperature range 10 mK to 2.17 K. In pure super uid in the zero temperature limit, three distinct critical velocities were observed with both tuning forks. We discuss the signi cance of all critical velocities and associate the third critical velocity reported here for the rst time with the development of large vortical structures in the ow, which thus starts to mimic turbulence in classical uids. The interpretation of our results is directly linked to previous experimental work with oscillators such as tuning forks, grids and vibrating wires, focusing on the behavior of purely super uid 4 He at very low temperatures.

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“…Quartz tuning forks have very high quality factors, of order 10 5 , making them sufficiently sensitive to study the mechanical properties of helium fluids at low temperatures. They have found many applications in superfluids research including measurements of viscosity [5][6][7], quantum turbulence in 4 He [8][9][10], cavitation [11], Andreev scattering in 3 He-B [12,13] and acoustic modes [14][15][16]. Here we describe their use as sensitive probes of ballistic quasiparticles in superfluid 3 He-B.…”

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confidence: 99%

A Quasiparticle Detector for Imaging Quantum Turbulence in Superfluid $$^3$$ 3 He-B

et al. 2014

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We describe the development of a two-dimensional quasiparticle detector for use in visualising quantum turbulence in superfluid 3 He-B at ultra-low temperatures. The detector consists of a 5 × 5 matrix of pixels, each a 1 mm diameter hole in a copper block containing a miniature quartz tuning fork. The damping on each fork provides a measure of the local quasiparticle flux. The detector is illuminated by a beam of ballistic quasiparticles generated from a nearby black-body radiator. A comparison of the damping on the different forks provides a measure of the cross-sectional profile of the beam. Further, we generate a tangle of vortices (quantum turbulence) in the path of the beam using a vibrating wire resonator. The vortices cast a shadow onto the face of the detector due to the Andreev reflection of quasiparticles in the beam. This allows us to image the vortices and to investigate their dynamics. Here we give details of the design and construction of the detector and show some preliminary results for one row of pixels which demonstrates its successful application to measuring quasiparticle beams and quantum turbulence.

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Behavior of quartz forks oscillating in isotopically pure4He in theT→0 limit

Cited by 35 publications

References 30 publications

Quantum turbulence generated by oscillating structures

Quantum turbulence generated by oscillating structures

Multiple critical velocities in oscillatory flow of superfluidHe4due to quartz tuning forks

A Quasiparticle Detector for Imaging Quantum Turbulence in Superfluid $$^3$$ 3 He-B

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