L. G. Shamanaeva

Statistical simulation of acoustic radiation propagation in the lower atmosphere by the Monte Carlo method

In this study, problems of statistical simulation of acoustic radiation propagation in the lower atmosphere along the vertical and horizontal paths by the Monte Carlo method and construction of the acoustic model of the atmosphere are considered. The influence of the geometry of problem being solved, radiation frequency, angle of source divergence, and outer scale of turbulence on the transmitted radiation intensity is discussed with allowance for the contribution of multiply scattered radiation.

Thermooptical Mechanism of Sound Generation by High-Power Laser Radiation Propagating in the Atmosphere

In the present paper, the results of experimental and theoretical investigations into the thermooptical mechanism of sound generation by high-power pulsed laser radiation (HPLR) propagating in the atmosphere are given. Experiments were performed with collimated and weakly-focused beams of a pulsed CO2 laser with a wavelength of 10.6 μm. A sound pulse was recorded with omnidirectional microphones placed at distances of 0.2–0.5 m from the laser beam axis and spaced along the laser beam propagation path whose length was a few hundred meters. A sound pressure level was measured with a precision impulse sound level meter, and time histories of acoustic pulses were also displayed on the screen of an oscilloscope. Based on these investigations, the methods of thermoacoustic sounding of the effective HPLR beam radius and divergence angle, the laser energy absorption coefficient, and the total laser energy have been suggested and realized together with the method of the diagnostics of HPLR propagation regime from the waveform or spectrum of the received acoustic signal.

Statistical estimates of time distribution of the monostatic sodar signal intensity

Time distribution of the monostatic sodar signal intensity has been obtained in the report with allowance for the contribution of multiply scattered radiation. Dependences of the sodar signal intensity on its parameters and atmospheric meteorological conditions are analyzed.

Influence of the outer scales of temperature and dynamic turbulence on the characteristics of transmitted acoustic radiation

In the present work, the problem of propagation of monochromatic acoustic radiation in the lower 500-meter layer of the plain stratified moving turbulent atmosphere is solved by the Monte Carlo method. The influence of the parameters of models of the outer scales of temperature and dynamic turbulence on the intensity of transmitted acoustic radiation intensity is investigated.

Acoustic Diagnostics of Laser Sparks in the Atmosphere

The results of an experimental study of the parameters of acoustic radiation generated by a laser spark made by focusing of a CO2 high-power pulsed laser radiation outdoors in a slightly dusty atmosphere are presented. An analysis of the acoustic pulse spectrum shows that the position of its maximum is determined by the local plasma-formation radius, and the position of its low-frequency minimum is determined by the laser spark length. A new method of laser spark diagnostics in real time is suggested that enables one to estimate the plasma-formation size distribution function and the transmission factor for laser radiation propagated in the atmosphere under conditions of laser breakdown. The results obtained are in agreement with the available experimental data.