Kiichiro Matsuzawa

Acoustic radiation force experienced by a solid cylinder in a plane progressive sound field

The acoustic radiation force experienced by a solid cylinder suspended freely in a plane progressive sound field is calculated, taking into account the elasticity of the cylinder. The results of numerical calculations are presented, indicating the ways in which the form of the frequency dependence of the radiation force function YP for cylindrical targets is affected by variations in the material parameters of the cylinder. The results are compared with those for solid spherical targets.

A new rigorous expansion for the velocity potential of a circular piston source

In the case of boundary value problems such as the sound scattering from a sphere placed in the nearfield of a plane piston source, it is sometimes essential to express the velocity potentials in terms of the orthogonal expansion. It is demonstrated in the present work that the Rayleigh surface integral, giving the velocity potential for a plane piston source surrounded by an infinite rigid flange, reduces to a rigorous expansion of the simplest form for a circular piston as series of spherical surface harmonics. The resulting equation is valid for any field points even on the piston surface. Sample calculations made with a microcomputer are presented with three‐dimensional and contour plots.

Acoustic radiation force on a solid elastic sphere in a spherical wave field

The acoustic radiation force on a homogeneous solid sphere placed freely in a spherical sound field in an inviscid fluid is calculated; the effect of the elasticity of the sphere material is studied. Calculated results are presented for a variety of solid spheres in water. Quite distinctive resonance departures from the rigid sphere solution are found.

Acoustic radiation force on a rigid sphere in the near field of a circular piston vibrator

The acoustic radiation force exerted on a rigid sphere whose time‐averaged center is at any specified point on the axis of a circular piston vibrator was investigated theoretically including points in the near zone of the radiation with a view to applying it to the absolute measurement of ultrasonic intensity. The velocity potential of incident waves in the near field was expressed in the form of an infinite series of spherical surface harmonics, thereby allowing the use of the conventional scattering theory to calculate the radiation force. The theoretical framework has the advantages that it includes neither approximations nor numerical integrations, and that it is applicable to elastic or compressible sphere cases with slight modifications of the boundary conditions.

A new expansion for the velocity potential of a circular concave piston

This paper presents a new method for calculating the velocity potential in the nearfield of a circular concave piston source in an infinite plane baffle for both the case where the vibration is normal to the piston surface and where it is parallel to the axis. The solution is given in the form of an infinite series of spherical surface harmonics in the spherical coordinate system, taking the origin at the center of curvature. The theoretical framework has the advantage that it includes neither approximations nor numerical integrations.

Fresnel diffraction: Some extensions of the theory

The rigorous expansion developed by the present authors for the velocity potential of a circular piston source [J. Acoust. Soc. Am. 74, 1044–1047 (1983)] is extended to include the space average pressure in the nearfield and the Fresnel diffraction of incident plane waves by an infinitely thin rigid disk. The present theoretical framework has the remarkable advantage that it includes neither approximations nor numerical integrations.

A new theory for the radiation from a concave piston source

The exact theory for the radiation of a circular concave piston surrounded by an infinite rigid baffle is presented. The Rayleigh surface integral, giving the velocity potential for a circular concave piston source, reduces to an infinite series of the simplest form when the origin of a system of spherical coordinates is taken at an arbitrary point on the acoustic axis. The theoretical framework has the advantages that it includes neither approximations nor numerical integrations and that it has application in solving other boundary‐value problems such as the sound scattering by a sphere whose center coincides with the origin in the field of a concave piston source.

Stochastic effect in grazing ion surface scattering

Abstract The energy distribution of scattered ions is determined by the trajectory and the stochastic effect. In this paper, we discuss the stochastic effect, which originates from the stochastic nature of electronic excitations, and derive a simple relation between the energy loss and the energy straggling associated with the stochastic effect (stochastic energy straggling). For the Firsov model of the inelastic energy loss, the stochastic energy straggling can be calculated directly from the magnitude of the energy loss. We also discuss the ratio of the stochastic to the trajectory energy straggling obtained from recent experiments.

Acoustic radiation pressure on a rigid sphere in a spherical wave field

An analysis has been made of the acoustic radiation pressure acting on a rigid sphere in a spherical sound field for the purpose of completing the work of Embleton [J. Acoust. Soc. Am. 26, 40–45 (1954)] from the angle of practical application. His presentation has been simplified mathematically and improved into a more general form. Numerical calculations have been made with particular emphasis on the difference from the results for incident plane progressive waves as a function of the density of the sphere, the size parameter, and the distance of the sphere from the sound source.

Study of the trajectory effect in grazing ion surface scattering

Abstract The energy distribution observed in ion scattering experiments is determined by two effects. One is the trajectory effect and the other is the stochastic effect. The trajectory effect has been studied quantitatively by means of computer simulations written for low energy Ar beams scattered off an ideal Cu(111) surface. The stochastic effect is briefly discussed within the Firsov model. The present study shows that both the energy loss and the energy straggling are proportional to the primary beam energy and that the stochastic effect is larger than the trajectory effect.