The velocity of second sound near Tλ

Williams, Richard; Beaver, S.E.A.; Fraser, Jim; Kagiwada, R.S.; Rudnick, I.

doi:10.1016/0375-9601(69)90383-1

Cited by 49 publications

(17 citation statements)

References 8 publications

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“…The various coefficients d1-d15 are abbreviations given by (31), (33), and (43) and by (92)]. At Tx sharp drops of the reflection coefficient RG6 and the transmission coefficient Dcl occur.…”

Section: Incidence Of a Sound Wave On The Free Helium Surface From Thmentioning

confidence: 99%

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Sound conversion phenomena at the free surface of liquid helium. I. Calculation of the coefficients of reflection, transmission, and transformation of sound waves incident on the liquid-vapor interface of helium

Wiechert

Buchholz

1980

J Low Temp Phys

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On the basis of a set of boundary conditions describing quite generally mass and energy transport processes across the free surface of helium II, the acoustic coefficients of reflection, transmission, and transformation of first sound, second sound, and the sound wave propagating in the vapor are calculated in the case of perpendicular incidence of sound waves against the liquid-vapor phase boundary. Considering rigorously the influences of the Onsager surface coefficients, the isobaric thermal expansion coefficients, and the thermal conductivities of the liquid and the ,Japor, we derive sets of equations from which the acoustic coefficients are determined numerically. For estimations, simple explicit formulas of the acoustic coefficients are given. It is shown that the evaporation and energy transport processes occurring at the free surface of helium H due to the incidence of sound waves may be connected with appreciable energy dissipation. The surface absorption coefficients of first, second, and gas sound waves are deduced.

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Section: Incidence Of a Sound Wave On The Free Helium Surface From Thmentioning

confidence: 99%

“…The system of Eqs. (46)-(50) with the abbreviations(31),(33),(43), and (52) may therefore be reduced to1 1 1 --2--RG6 +-S--De1 + i(o(pL--Ree + pLU2CL Te2--ioJ oeLTo~ = --(55) UG UG (-~G q-gl) RGe-gl~'Ze2-itopeTes =X-Kl (56) ueIt turns out that Eq. (50) is identically fulfilled.…”

mentioning

confidence: 99%

Sound conversion phenomena at the free surface of liquid helium. I. Calculation of the coefficients of reflection, transmission, and transformation of sound waves incident on the liquid-vapor interface of helium

Wiechert

Buchholz

1980

J Low Temp Phys

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“…Figure 3 shows the results for resistive film transducers for various attenuations caused by injected turbulence. The quality factor varies from 1010 to 390, thus the attenuation o~ = n~r/QL from 2• 10 -3 to 6 X 10 -3 cm - 1 We immediately see that circle fittings are excellent and all circle centers are on a straight line drawn from the origin. Formula (1) shows that the resonant amplitude A, = GAoQn/ncr is linear in Q,, and we must have Q,/A, constant for various attenuations; we measure Q3/Ar --50.75 4-1% for all circles, that is, the resonant amplitude is proportional to the quality factor with an excellent accuracy.…”

Section: The Kennelly Circlementioning

confidence: 87%

Pinning of vortices in nucleopores. Effect on second-sound resonators

1980

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“…For this purpose, Sherlock and Edwards 2 and Williams et al 3 developed the oscillating superleak transducer (OST), which is essentially a loudspeaker (or microphone) with a porous membrane. Since then, it has been exclusively employed in second-sound experiments in helium.…”

Section: Introductionmentioning

confidence: 99%

Peshkov transducers of second sound

Henjes

Liu

1988

J Low Temp Phys

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A system made up of a pair of Peshkov transducers situated at the opposite ends of a one-dimensional resonance cavity is investzgated theoretically. Included are the dissipative effects of thermal diffusion and normal viscous slip through the superleak, Compared to the oscillating superleak transducer, there are two noteworthy differences: (I) The Peshkov transducer has more pronounced first-sound resonances at lower frequencies, complicating the interpretation.(2) Due to the separation of membrane and superleak, one can more easily reduce transducer dissipation, important in 3He and in 4He close to T~.

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The velocity of second sound near Tλ

Cited by 49 publications

References 8 publications

Sound conversion phenomena at the free surface of liquid helium. I. Calculation of the coefficients of reflection, transmission, and transformation of sound waves incident on the liquid-vapor interface of helium

Sound conversion phenomena at the free surface of liquid helium. I. Calculation of the coefficients of reflection, transmission, and transformation of sound waves incident on the liquid-vapor interface of helium

Pinning of vortices in nucleopores. Effect on second-sound resonators

Peshkov transducers of second sound

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