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Acoustic interferometer
About: Acoustic interferometer is a research topic. Over the lifetime, 1493 publications have been published within this topic receiving 19355 citations.
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17 May 1994
TL;DR: In this article, the set of coupled equations for the elastic deformation and the phonon density or second sound was reduced to a simple tractable form and the dispersion equation for the coupled waves consisting of the acoustic modes and second sound has been derived.
Abstract: An expression has been derived for the collision operator for phonons in a solid, which is valid at very low temperatures. The set of coupled equations for the elastic deformation and the phonon density or second sound has been reduced to a simple tractable form and the dispersion equation for the coupled waves consisting of the acoustic modes and second sound has been derived. It is shown that only the longitudinal mode interacts with the second sound. It is also shown that as a result of the interaction with the second sound, the longitudinal velocity along the principal axis acquires a correction term that is proportional to bothγ
2 andT
4.
01 Jan 1977
01 Jan 1984
TL;DR: In this paper, a new technique is described to measure temporal periodic fluctuations in the free-carrier density of s ilicon, based on the electronic dependence of the elastic constants, and involves the measurement of the perturbation in phase of an acoustic wave propagating through a region of modulated carrier density.
Abstract: A new technique is described to measure temporal periodic fluctuations in the free-carrier density of s ilicon. It is based on the electronic dependence of the elastic constants, and involves the measurement of the perturbation in phase of an acoustic wave propagating through a region of modulated carrier density. An experlment is described in which the bulk lifetime of photogenerated carriers is determined using this technique. A theory is developed to predict the acoustic phase perturbation, and is found to agree well with experiment.
TL;DR: In this article, the feasibility of the one-dimensional theory by which the transmission of acoustic waves from a solid cylinder into a liquid is analyzed with the acoustic impedance was discussed, and experiments were performed on a cylinder made of Cu with a size of 1.98mm o © 51.96mm t.
Abstract: We discuss the feasibility of the one-dimensional theory by which the transmission of acoustic waves from a solid cylinder into a liquid is analyzed with the acoustic impedance. For this purpose, experiments were performed on a cylinder made of Cu with a size of 1.98mm o © 51.96mm t . The frequency of acoustic waves was varied from 0.80 to 1.3MHz. The characteristics of the Pochhammer mode in the solid cylinder are clarified by certain equivalent acoustic impedances. At low frequencies from 0.80 to 1.0MHz, several definitions of the equivalent acoustic impedances work effectively. At intermediate frequencies near 1.1MHz, the equivalent impedances available are those defined near the lateral surface of the cylinder. At high frequencies from 1.15 to 1.3MHz, the experimental transmission rate of acoustic waves decreases considerably, and the adequate impedance is obtained using the energy flux and the axial component of the velocity field in the cylinder.