Sound Velocity In Solids Research Articles

Acoustooptic methods for measuring sound velocity

This paper gives a brief review of some studies of acoustooptic methods for measuring sound velocity in solids performed at the Department of Acoustoelectronics and Acoustooptics of the Institute of Semiconductor Physics, Siberian Branch of the Russian Academy of Science.

Cumulative phenomena due to the collision of laser-driven projectiles related to fast ignition and astrophysical applications

The results of contemporary investigations of cumulative phenomena due to the collision of projectiles laser-accelerated up to the velocities significantly higher than the sound velocity in solids are reviewed. The discussion is focused on the applications directed on the development of a concept of fast ignition by projectile impact and the laboratory modeling of astrophysical phenomena. Low-entropy acceleration of a projectile in a dense state up to ‘thermonuclear’ velocity of the order of 1000 km/s is grounded. The parameters of extreme matter state induced by laser-accelerated projectiles collision, namely, energy flows, pressure and temperature, spontaneous magnetic field and thermonuclear neutron yield are discussed. Astrophysical phenomena due to collision of cosmic objects such as a creation of a crater by meteorite's impact, as well as the emerging of a shock wave to a star surface, and formation of jets, ionization and emission waves are considered.

Superposed pulse echo overlap method for ultrasonic sound velocity measurement

A superposed pulse echo overlap method is described as a method to determine ultrasonic sound velocity. This method has the advantages both of the pulse echo superposition and the pulse echo overlap methods; round-trip time of echoes through the specimen was determined by overlapping the superposed echoes on the oscilloscope. Accurate and quick measurements of sound velocity in solids and liquids become possible by this method.

Dynamics of Picosecond Laser-Generated Acoustic Waves in Solids

Generation and propagation characteristics of picosecond laser-generated acoustic waves in solids were studied using an optical detection technique and a ZnO piezoelectric transducer. The propagation of laser-generated acoustic waves was directional. At the early stage of propagation, the propagation velocity of the wavefront exceeded the sound velocity in solids. The generation and propagation behavior of acoustic waves are very sensitive to the interaction conditions between laser pulses and solid surfaces. The formation and expansion of laser-generated plasmas affect the generation dynamics of acoustic waves.

Acoustooptic method for measuring sound velocity in solids

An acoustooptic interferometric method for measuring sound velocity in solids is described. This method allows one to measure sound velocity in arbitrary materials by using a composite buffer-sample resonant system. Materials which are non-transparent to the laser radiation or such which are acoustooptically inactive are also subject of this investigation.

Acoustooptical method of measuring sound velocity in solids

A method of measuring the sound velocity in acoustooptic d y active solids has been investigated. The method is based upon the fact that the velocity can be determined from the frequency difference between two resonant standing-wave modes in an acoustical interferometer. Instead of measuring the transformed acoustical impedance of the interferometer, the energy in the modes is probed with a laser beam, resulting in easy and accurate measurements. The method is applied to measure the sound velocity in germanium, which is the most utilized material in acoustooptical modulators for CO2-lasers. The velocity of a longitudinal acoustical wave propagation in the [11l]-direction in single crystal germanium was found to be 5481±6 m/s at room temperature.

Ultrasonic Thermometry for Nuclear Reactors

Ultrasonic thermometry, based on the temperature dependence of sound velocity in solids, has been demonstrated under ideal laboratory conditions beyond 6000R. Integrated fluxes (nvt) of 2.6 × 1019 fast and 8.7 × 1019 thermal do not perturb the velocity/temperature relationship. Ta protective sheaths prevented carbon contamination for 1 hr at 5100R, in a program simulating temperature measurements in the graphite/hydrogen atmosphere of a nuclear rocket engine. Tests have also been performed in liquid sodium at 1200R, and separately, inside a 1.6 mm dia Ta tube heated to 5500R, simulating temperatures inside UO2-fueled pins of fast breeder reactors.

On the Molecular Theory of Sound Propagation in Liquids

A short review is given on the molecular theory of sound velocity in solids, liquids, and gases, with particular attention paid to liquids. A simple rudimentary theory is presented to explain the manner in which sound is propagated in the primary alcohols. This theory assumes that the velocity between molecules is different from the velocity within the molecules. Computations of these velocities indicate that both are finite and of the same order of magnitude as the observed sound velocity in the liquid. Comparisons at a temperature of 0°C with other molecular data appear to substantiate the results obtained.