Gennadii A. Lyakhov

Energy efficiency of the vibration-accelerated liquid mass transfer in a channel

The method of vibration-enhanced liquid mass transfer in a channel with oscillating walls is described. Homogeneous (over the channel length) transverse oscillations of the walls can provide for a significant increase in the mass transfer rate. The energy efficiency of the proposed vibrational technology is calculated.

Electromagnetic Excitation of the Discharge and Optical Absorption in Sulfur Vapor

The light emission spectra of a discharge excited by the high-frequency and microwave radiation sources in mixtures of sulfur with buffer gas (argon or neon) were experimentally studied. Various stages of changing the characteristic spectra in the process of discharge development were revealed. The temperature dependences of the absorption spectra of sulfur saturated vapor were measured up to 1000 K. A linear shift of the absorption line from the violet to the green region with temperature was found. The absorptivity rises steeply and reaches of 3 cm-1 at T=1000 K. The analysis shows that the same temperature dependence is observed for the maximum of the emission line. The filtering of light by colder sulfur vapor in the vicinity of the walls is supposedly responsible for the increase in the optical absorption at shorter wavelength. This explains the nontrivial increase in the wavelength of maximum of the spectral radiant intensity with temperature.

Microwave and rf excitation of a discharge in sulfur vapor with added neon

An experimental investigation was made of the transient emission of a discharge excited by microwave radiation in mixtures of sulfur and rare gases. Several typical spectral types of emission were identified which alternate over time.

Optical breakdown in a liquid : The slow phase of the dynamics of cavity collapse and a noncontact technique for pressure measurement in a liquid

It is demonstrated that, in the case of optically probing the breakdown region, a pulsed signal is formed due to the acoustic pulses produced by the breakdown and collapse of the cavitation cavity. The measured dependence of the delay time of the second pulse on the hydrostatic pressure in the liquid and the pressure of saturated vapor agrees well with the theoretical dependence corresponding to the hydrodynamic model of the cavity. On the basis of the optical cavitation effect, a technique is proposed for a noncontact measurement of hydrostatic pressure in a liquid enclosed in a sealed cell. The range of applicability of the technique is evaluated.

Remote Sensing of Acoustic Signals and Perturbations Generated in Dense Medium

Distributed reflections of electromagnetic waves by running acoustic grating in two-layer medium have been considered as the new remote sensing methods for the registration of signals generated in dense medium. The theoretical analysis has been done for the application of this method to atmospheric reception of signal from underwater acoustic source. The effect of unsteady air-water interface irregularities due to wind waves has been examined. Calculations have shown that sufficiently intense acoustic signal can be received from deep ocean (down to kilometer) at a high altitude in atmosphere (up-to kilometers now and higher in future). The completed laboratory experiments have also confirmed the possibility of remote sensing registration of signal from underwater acoustic source. The reception of signal through interface (boundary surface) between different media has application on wide range of scales, from microscale (crystal lattice defect motion, for example) to geophysical one (ocean bottom layers detrusion or underwater volcano eruption, etc). In this situation the signal receiver is disposed in the other medium (usually in air) outside and often away from the dense medium where perturbation (or signal) source under examination is located. In dense conductive medium (such as metal, electrolyte, sea water) the optimal carrier of signal or information about perturbation is the acoustic waves. However acoustic waves attenuate drastically in transiting the interface and relatively soon decay when propagate in air. Therefore immediate registration of such acoustic waves away from the interface is impossible in many cases (particularly in high frequency range).

Microwave driven anti-Stokes Brillouin scattering in an ionized medium. The method of remote sensing of atmospheric aerosols

The theory of stimulated Brillouin scattering in a ionized isotropic medium is developed. It is shown that if an electric field at a frequency of 2F, where F corresponds to the Brillouin shift, is applied to the scattered volume then amplification of the anti-Stokes component of the scattered wave takes place. The method of remote sensing of atmospheric aerosols is proposed.

The Laser Amplifier with a Stimulated Scattering Mirror

Abstract A laser scheme with scattered volume employed as a cavity mirror is considered. The laser threshold and the output pulse characteristics are calculated.

Frequency doubling in liquid crystals. Optical thickness of a sample

A theoretical investigation is made of the mechanisms responsible for the experimentally observed nonmonotonic dependence of the intensity of a harmonic generated in a liquid crystal on the thickness of a nonlinear sample. These mechanisms included scattering by fluctuations of the orientation and a change in the order in a liquid crystal in regions far from the walls of a cell.