Showing papers on "Acoustic interferometer published in 1966"

Measurements of Attenuation and Dispersion of Sound by an Aerosol

Abstract: Attenuation and dispersion of sound by an aerosol, composed of oleic acid and a nitrogen carrier gas, are measured with an acoustic interferometer. Mean particle size and concentration are measured in situ by spectrophotometric tests. The measurements of attenuation and dispersion show good agreement with the theory in the range of ω(τd)32 covered, where ω is circular frequency and (τd)32, is dynamic relaxation time of the particles. In particular, the maximum attenuation per wavelength and the maximum dispersion, which are predicted by the theory, are confirmed experimentally.

Velocity of Ultrasonic Waves in Single Crystals of Calcium Fluoride

Abstract: THE elastic constants of crystals are commonly determined by measuring the velocities of propagation of acoustic waves in different principal crystal directions and applying well-known formulae1. For crystals of high perfection it has generally been reported that the measured velocity of sound of a given substance is substantially independent of impurity concentration and is a slowly varying function of temperature. There have been relatively few investigations of the dependence of acoustic velocity on impurity density due to the fact that, until recent years, the preparation of highly doped single crystals of high perfection was virtually impossible. We have investigated ultrasonic propagation in a number of calcium fluoride monocrystals grown in the direction by the Czochralski technique. Some of the crystals were of high purity and others were doped with up to 2 per cent significant impurity for experiments on laser action. They were all of comparable perfection, with measured dislocation densities lying in the range 104–105 cm−2. Samples for measurement were cylinders with opposite ends cleaved and finely polished to plane-parallelism.

Ion Acoustic Waves in Mercury‐Vapor Discharges

Abstract: The external excitation of the ion acoustic waves is examined. The propagation and reflection of the waves and the standing waves between the probe and anode are observed.