Experimental Determination of the Fourth Sound Velocity in Helium II

Shapiro, Kenneth A.; Rudnick, I.

doi:10.1103/physrev.137.a1383

Cited by 141 publications

(25 citation statements)

References 10 publications

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“…As a usual way out, the blockade of the normal fluid flow may be effected by embedding the helium II in a porous medium as was done in the experimental investigations of, e.g., Refs. [3] and [4]. Then there is no longer a well-defined geometry.…”

Section: Introductionmentioning

confidence: 92%

Dispersion relations of wave modes in helium II layers

Wehrum

Meinhold-Heerlein

1973

Z. Physik

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Dispersion relations of (sound-like) wave modes, which can exist in a helium II layer of arbitrary width, are calculated numerically. The basis of our considerations is the complete system of the linearized Landau-Khalatnikov equations, in which only the dissipative processes involved with I/and ~2 are taken into account. Apart from the linearization, no approximation or averaging is performed. The thermal expansion of helium II is taken into account. Symmetry properties of the velocities of flow, usually required, are dropped here. A hint is given as to how all the Khalatnikov coefficients may be measured by sound absorption experiments.

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Section: Introductionmentioning

confidence: 92%

Dispersion relations of wave modes in helium II layers

Wehrum

Meinhold-Heerlein

1973

Z. Physik

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“…To observe fourth sound experimentally, superfluid is channeled through a tube packed with a powder that immobilizes the normal component [24]. In such a setup, momentum is not conserved, so in order to compute the sound velocity we need to find the phase velocity for linearized fluctuations around a static background.…”

Section: Fourth Soundmentioning

confidence: 99%

Holographic Superfluid and STU Model

Saadat

Pourhassan

2012

Int J Theor Phys

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“…The fourth coefficient in each of the two cases is to be obtained from the initial conditions. Equations (10)- (13) have been written in the form which suggests that the two coefficients to be obtained from the initial conditions are f 0 (3) and fo (A°. The six ratios determined algebraically from Eqs.…”

Section: The Connectionmentioning

confidence: 99%

“…The waves in He-II which have already been observed are: acoustic waves (first sound) , 6,7 conductive thermal waves (second sound) , [8][9][10][11] surface film waves (third sound), 12 acoustic waves in narrow channels (fourth sound), 13 and thermal waves in channels. 14 Many of the properties of He-II, including all of those mentioned in this paper, can be described quantitatively by the two-fluid model of liquid helium.…”

Section: Introductionmentioning

confidence: 99%

Radiation of Sound in He-II Films

Pollack

1967

Phys. Rev.

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ment in which the deviation from the Langevin theory calculated above could be seen. VI. CONCLUSIONWe have demonstrated that the Langevin theory for electron mobility in a hard-core gas can be derived from irreversible quantum statistics without postulating any relaxation time. Rather, a momentum-dependent Static He-II films which are locally disturbed are investigated with the two-fluid model. It is assumed that motion of the normal fluid is retarded by a viscous force per unit volume rcopv n , in which r is a dimensionless viscosity parameter whose value in He-II films is shown to be 10 2 <^<10 4 . A general surface wave and thermal disturbance is propagated through the film by two wave modes: a third-sound wave and a new highly attenuated, wave; these are first redescribed. For arbitrary initial conditions, the amounts of each mode produced are derived for a general experimental case. In particular, conditions which will produce third sound alone and the new mode alone are derived as functions of temperature and r. It is shown that pure third sound is difficult to produce, since the requirements on phase between the surface wave and temperature excitations are not experimentally natural ones. It is shown that, when the film is locally disturbed with a pure thermal excitation varying as exp^W, both modes are excited equally and are 180° out of phase, so that the net surface is undisturbed. When the film is locally disturbed with an isothermal pure pressure excitation, then for large viscous force on the normal fluid, almost all of the displacement is in the new mode. The motions of the film variables characteristic of each of the modes are analytically obtained in general, and described quantitatively for a particular case. In the new mode, the normal fluid and superfluid move with almost the same phases and velocities, and are 180° out of phase with the surface wave. In the third-sound mode, the superfluid moves in phase with the surface waves but the normal-fluid motion is more complicated. The results are compared with Lifshitz's results on first and second sound in bulk helium.

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Experimental Determination of the Fourth Sound Velocity in Helium II

Cited by 141 publications

References 10 publications

Dispersion relations of wave modes in helium II layers

Dispersion relations of wave modes in helium II layers

Holographic Superfluid and STU Model

Radiation of Sound in He-II Films

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