Turbulence Experiments in Superfluid 3He at Very Low Temperatures

Fisher, S. N.

doi:10.1007/978-3-211-09447-1_5

Cited by 6 publications

(10 citation statements)

References 47 publications

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“…The dashed cyan lines show (from the left) the KO-41 (-5/3) scaling, the energy equipartition +2) and, at the right, the (-5/3) LN spectrum Eq. [ 13 ] Ψ( , t is the complex condensate's wave function, of the interaction between bosons, s density velocity to Ψ = exp( Θ) /M , which confirms Landau's intuition is irrotational. It can be shown that, at length scales M E , the GPE reduces to the classical continuity (compressible) Euler equation.…”

Section: IVsupporting

confidence: 59%

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Velocity spectra of quantum turbulence: experiments, numerics and models

Barenghi,

L'vov,

Roche

2013

Preprint

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Turbulence in superfluid helium is unusual and presents a challenge to fluid dynamicists because it consists of two coupled, inter penetrating turbulent fluids: the first is inviscid with quantised vorticity, the second is viscous with continuous vorticity. Despite this double nature, the observed spectra of the superfluid turbulent velocity at sufficiently large length scales are similar to those o ordinary turbulence. We present experimental, numerical and theoretical results which explain these similarities, and illustrate the limits of our present understanding of superfluid turbulence at smaller scales.

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Section: IVsupporting

confidence: 59%

“…In this section we shall limit our discussion to experimental techniques for 4 He. The methods used in 3 He, at temperatures which are one thousand times smaller, are rather different 13 , and we shall only cite the results in 3 He which are directly relevant to our aim.…”

Section: Experiments: Flows Probes and Spectramentioning

confidence: 99%

Velocity spectra of quantum turbulence: experiments, numerics and models

Barenghi,

L'vov,

Roche

2013

Preprint

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“…As noted in Ref. 16 , formula (13) gives only rough estimates for L which are correct within a factor of 2. This is not surprising since the model 13 ignores an influence of geometry and orientation of vortex lines on the Andreev reflection.…”

Section: Screening Mechanisms In Andreev Reflection From Vortex Tmentioning

confidence: 93%

“…On moving from one side of the minimum to the other, the excitation's group velocity reverses: quasiholes and quasiparticles with similar momenta travel in opposite directions. In the reference frame of a superfluid moving with velocity v, the dispersion curve tilts to become E(p) + p · v 16 . Quasiparticles which move into a region where the superfluid is flowing along their momentum direction will experience a potential barrier.…”

Section: Introductionmentioning

confidence: 99%

“…[4][5][6][7][8][9][10] ) and in 3 He-B [11][12][13][14][15] . The most promising technique which is being de-veloped for superfluid 3 He-B utilizes the Andreev reflection of quasiparticle excitations from superfluid flow 16 . (This technique was first developed to study quantum turbulence in stationary samples [11][12][13] , and has since been extended to rotating samples 15 .)…”

Section: Introductionmentioning

confidence: 99%

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Visualization of quantum turbulence in superfluid He3−B : Combined numerical and experimental study of Andreev reflection

et al. 2017

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We present a combined numerical and experimental study of Andreev scattering from quantum turbulence in superfluid 3 He-B at ultralow temperatures. We simulate the evolution of moderately dense, three-dimensional, quasiclassical vortex tangles and the Andreev reflection of thermal quasiparticle excitations by these tangles. This numerical simulation enables us to generate the twodimensional map of local Andreev reflections for excitations incident on one of the faces of a cubic computational domain, and to calculate the total coefficient of Andreev reflection as a function of the vortex line density. Our numerical simulation is then compared with the experimental measurements probing quantum turbulence generated by a vibrating grid. We also address the question of whether the quasiclassical and ultraquantum regimes of quantum turbulence can be distinguished by their respective total Andreev reflectivities. We discuss the screening mechanisms which may strongly affect the total Andreev reflectivity of dense vortex tangles. Finally, we present combined numerical-experimental results for fluctuations of the Andreev reflection from a quasiclassical turbulent tangle and demonstrate that the spectral properties of the Andreev reflection reveal the nature and properties of quantum turbulence.

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