Home – Home – Jornals – Atmospheric and Oceanic Optics 2014 number 4

Last year, September 16-20, the XI International Conference “Atomic and Molecular Pulsed Lasers - AMPL-2013” has been held in Institute of Atmospheric Optics SB RAS (IAO SB RAS), Tomsk, Russia. The XI AMPL Conference was traditionally devoted to physical processes in laser active media, new active media and pumping methods, new laser development technologies, fundamental issues of laser physics, non-coherent UV and VUV-radiation sources.

Cupper vapor laser beam was focused on plasma region, where nanoclasters are admittedly formed under ceramic target sputtering in oxygen environment. In normal to beam direction, optical signal are recorded and handled with temporal, spatial, and spectral resolution; hardware and software means are described. Low power emission of laser heated particles has been found in infrared region near dielectric substrate.

Binary mixtures of methanol, ethanol, isoamyl alcohol, and acetic acid with water in various proportions have been studied using Raman spectroscopy. Upon variations in organic solvent concentration in water changes in intensities ratio for bands of СН- and ОН-group stretching vibrations within a spectral range 2600-3800 cm^-1 were observed. For quantitative characterization of partial concentrations of solvents mixed with water, we have chosen an integral intensity I_CH of CH-stretching band, normalized to the sum (I_CH + I_OH) of both СН- and ОН-group stretching bands taken within the 2600-3800 cm^-1 wavenumber interval. Using this type of intensity normalization, we get the value I_CH/( I_CH + I_OH) which depends linearly on the volume fraction of an organic solvent in aqueous solution throughout the whole studied range of its concentration. Raman spectroscopy with normalization to sum of both CH- and ОН-group stretching bands gives possibility of non-contact detection and quantification of flammable or toxic liquid mixed with water. Relative accuracy of concentration determination for ethanol, methanol, and acetic acid in water was achieved as good as 0.5, 1.1, and 1.5%, respectively.

During the high-voltage nanosecond discharge in a gap filled with deuterium, hydrogen, helium, and argon at a pressure of 1-60 torr, using a cylinder with lateral surface made of thin tungsten wires split at the end as a potential electrode and a flat deuterated zirconium target as a material splashing of electrodes was observed. Mainly, there is material splashing on the potential electrode for both positive and negative polarities of the pulser. As the gas pressure increases the reduction of the track lengths of fluttering from electrode hot glowing drops was observed.

In this article the authors show the results of optical inflation of samarium and europium vapors by radiation of eximer XeCl*, XeF, and KrF* lasers. The authors got electronic stimulated Raman scattering radiation of XeF* laser. In samarium, vapor radiation was got at wavelength λ_С = 589.1 and 608.2 nm. During irradiation of europium vapor by radiation of KrF*, laser electronic stimulated Raman scattering was observed in this vapor. This radiation was observed at wavelength λ_С = 2501 and 2414 nm.

A general form of the kinetic equation (nonlinear diffusion equation) for filament number density considering the effects of their generation and decay is stated. It consists of the phenomenological parameters, which have been determined from the direct numerical simulation of propagation of a high-power femtosecond laser pulse (HPFLP) based on the stationary nonlinear Schrödinger equation (NSE) for a series of the threshold particular cases.

This paper presents the formation and decay of diffuse “channels” of a corona discharge in atmospheric pressure air using modulated voltage pulses. Photomutipliers, a high-speed camera, and a copper bromide vapor laser monitor are used to register the radiation from the corona discharge. It is shown that the radiation of corona discharge diffuse “channels” is modulated in time and the pulse repetition frequency is twice as high as the voltage pulse modulation frequency (~ 290 kHz). It is also demonstrated that at a corona discharge channel curves the breakdowns can occur over a short distance, which reduces the blurring of the channel.

Data on the parameters of X-ray pulse at the repetitively pulsed nanosecond discharge in the nitrogen were obtained. It was shown that during the transition from diffuse to corona discharge the X-ray pulse duration increased. A theoretical modeling of the nonstationary process of corona discharge development at atmospheric pressure when nanosecond voltage pulse applied across the gap was performed. Spatial and temporal distribution of concentration of charged particles and the electric potential in the discharge gap were calculated. It was shown that when the nanosecond voltage pulse came to the end non-monotonic potential distribution formed in the gap. It should be said that at the same time the electric field is concentrated in a narrow region of the front of the ionization wave.

The initial stage of the breakdown of sulfur hexafluoride (SF₆) and nitrogen in the non-uniform electric field at high pressures was investigated. High voltage pulses with amplitude of up to 350 kV were applied across the discharge gap with "point-plane" geometry of the electrodes. The experimental results on the dynamics of the light emission from the different zones of the discharge gap can be explained by formation of the ionization wave started from the potential electrode with a small radius of curvature. It was found that the speed of ionization wave front in nitrogen and SF₆ is higher in the second half of the discharge gap as compared to the first one. At increasing SF₆ and nitrogen pressure the speed of ionization wave front was shown to decrease. At negative polarity of high voltage pulse the average speed of ionization wave front was shown to be of ~ 2 cm/ns in SF₆ at a pressure of 0.25 MPa and ~ 3.6 cm/ns in nitrogen at a pressure of 0.3 MPa.

In this paper, the frequency and energy characteristics of a MnBr vapor laser with the inner reactor, i.e., with gas vapors being produced within a gas discharge tube, and the dependence of the average output power on different parameters are studied. The values of the GDT wall temperature and buffer gas pressure required for obtaining the maximum output power are determined. It is shown that the active elements of this kind are as good as the elements with a conventional way of gas vapor production. For a medium on transitions of Mn atoms, the PRF of 100 kHz is obtained for the first time. The results of using the active element as a brightness amplifier in active optical systems are also presented, and the research of amplifying characteristics is carried out.

By numerical simulations was investigated the effect of the mixture of gases in the XeF(C-A) amplifier hybrid laser system THL-100 on the main channels of energy loss. It is shown that an increase in the buffer gas pressure N₂ from 100 to 760 Torr leads to an increase in the fraction of absorbed energy transmitted to the upper laser level XeF(C, ν = 0). Increasing the partial pressure of XeF₂ causes an increase of energy loss in the process of quenching XeF(B , C) and reduce the energy transferred to the XeF(C, ν = 0) state.

The optimal stretcher-compressor scheme is designed for the use in facilities with chirped pulse optical parametric amplification under picosecond (~ 100 ps) pumping. It enables one to achieve petawatt peak power in less than 10 fs pulses with high contrast and low aberrations. The stretcher design is based on an Öffner telescope with spherical mirrors and two diffraction gratings, one being placed in the center of spherical mirrors. It is shown to be the only possible aberration-free stretcher design with spherical mirrors. Performed analysis shows that the compressor consisting of four transmission diffraction gratings with 112 × 125 mm aperture, 3 mm thickness and chirped mirrors adding -4500 fs² dispersion with 100 mm aperture allows amplified pulse compression with up to 1 PW peak power and less that 10 fs pulse duration, with total B -integral being less than 1. The designed stretcher-compressor system is planned to be implemented in the high power femtosecond laser facility developed at ILP SB RAS.

Spectral parameters of non-chain chemical laser on mixtures of hydrogen and deuterium with SF₆ pumped by a discharge with UV illumination from generator with inductive energy storage and by a diffuse discharge formed in a non-uniform electric field due to preionization by run-away electrons (REP DD) are compared. It is shown that high uniformity of volume discharges formed in the active laser medium allows the increase in the number of laser lines. Therewith intense cascade transitions appear in the laser spectra and lasing efficiency on HF (λ = 2.8 ÷ 3.2 mm) and DF molecules (3.8 ÷ 4.2 mm) reaches its ultimate value. It is shown that the volume discharge initiated by run-away electrons (REP DD) in gas mixtures with SF₆ is an efficient pumping method of lasers on HF(DF) molecules.

The explosive properties of a mixture of benzotrifuroxane and anthracene in the form of a molecular complex (mixing of the components at the molecular level) and a mechanical mixture with the same molar ratio of the components are investigated. It is found that the molecular complex is an individual explosive with modified properties.

In order to study the phase transformations of ytterbium under shock compression, the electrical resistance of ytterbium at the initial temperatures of 77 and 290 K and a shock pressure of p ≤ 20 GPa is measured. The dependence of ytterbium resistance on pressure is nonmonotonic and indicates three successive phase transitions. At p ≈ 2 GPa, ytterbium enters a state with a high electrical resistance of the semiconductor type. The ytterbium bandgap at p ≈ 1.8 GPa is estimated as ≈ 0.02 eV. At p ≈ 3 GPa, the electrical resistance of ytterbium decreases due to a polymorphic phase transition The electrical resistance grows with further increase in pressure, and at p > 11 GPa, it does not change. The nature of the third transition is determined by calculating the temperature of the sample under shock compression. Analysis of the dependence of sample temperature on shock pressure, together with the phase diagram of ytterbium, suggests that the third transition is caused by ytterbium melting.

The trajectory of motion of a copper shell, the velocity of its flight, and the pressure of the explosion products on the inside of the copper shell were simulated. It was found that there is a significant difference in pressure behavior between experiments and calculations performed using the standard equations of state of explosives and explosion products. Most likely, there is a significant contribution of kinetic processes to the energy release behind the Jouguet point. In this case, the conversion of explosives to explosion products apparently include not only exothermic reactions but also endothermic processes.

The possibility of low-temperature oxidation of a solid carbonized coal residue in a mixture of NH₄NO₃ and supercritical water (723 K and 30 MPa) is shown for the first time and its mechanism is described. Conjugate processes of oxidation of the carbonized residue and formation of combustible gases H₂ and CH₄ caused by the participation of H₂O in redox reactions was found. It was established that the ash residue has a high porosity and consists of agglomerated nanoparticles of silicon and metal oxides.

The paper presents results of numerical experiments performed to evaluate the effective viscosity of a fluid-proppant mixture, used in hydraulic fracturing. The results, obtained by two complimenting methods (the particle dynamics and the smoothed particle hydrodynamics), coincide to the accuracy of standard deviation. They provide an analytical equation for the dependence of effective viscosity on the proppant concentration, needed for numerical simulation of the hydraulic fracture propagation.

The article reports the geomechanical assessment of rockburst-hazardous Khingansky manganese ore body (Poperechny extraction site) at the early stage of development. The researchers accomplished geodynamic zoning of the ore body, analyzed mining-and-geological and mine-technical conditions, and estimated parameters of physico-mechanical properties of host rocks and ore. Using numerical modeling, the stress state of the ore body and rock mass at various mining stages is assessed, and the bottom part of the Khingansky ore body is considered rockburst-hazardous.

The stress-strain state in rocks around an excavation is assessed by the values of stresses “at infinity”, i.e., it is required to know stress distribution in an intact rock mass. The authors propose a new method of the stress-strain state assessment for an arbitrary cross-section excavation based on direct measurement of displacements of the excavation walls, using the Kolosov-Muskhelishvili formulas. Under analysis are the excavations shaped as circular and elliptical cylinders.

The authors present the results of underground excavation lining examination aimed at detecting inhomogeneities in the lining (reinforcement metal, voids, weakening) and recommend on selecting the lining sites to be optimal for measurement hole drilling based on field observations.

In focus is the problem of mathematical modeling of zonal disintegration of rocks around a deep-level excavation. In the framework of the elastic model of isotropic material, the author analyzes the two-dimensional case on stress field in rocks around a circular cross-section excavation. The acting compressive stresses at infinity depend on the depth of the excavation occurrence. The shear stress analysis has shown that in rocks around the excavation, the increased shear stress circle zone appears at the distance from the excavation center. The increased stresses come before the rock mass disintegration and create conditions for next destruction circles. The author dwells on probable influence of initial hydrostatic stress on the disintegration law. In modeling, the zonal disintegration circles appear at larger distance from the excavation center than in the experiment, due to the idealization of the classical problem formulations in rock mechanics.

The processes of free and absorbed coal gas filtration and diffusion are described using the earlier offered mathematical model in the form of the set of nonhomogenous parabolic equations. Movement of such medium is considered in the form of a progressive (shock) wave, i.e., the self-similar approximation. It is proved that the problem reduces to the plane boundary value problem of the quality theory of the regular differential equations. The effect of the gas sorption relaxation time on the shock wave structure is quantitatively estimated.

The general regular patterns in focalization of deformation at pre-failure stage in rocks under compression are found and analyzed (sylvinite, marble sandstone). Applicability of speckle-photography methods in problems on rock deformation and failure is proved. The authors define the self-sustained behavior of the focalized plastic deformation in rocks under compression, due to effect of various plastic micromechanisms. The self-sustained structures in rock specimens under compression propagate at a rate of ~ 10-5 ÷ 10-4 m/s (0.3-3 km/yr), which is close to slow motions induced in the earth crust by an earthquake or a rockburst. The ratio of the experimental and calculated failure times is correlated with the coordinates of the failure points in the test rock specimens.

Under consideration is the stress-strain state in the edge area of a bed when mine faces approach a vertical fracture. The author illustrates the stress-strain state analysis using the previously derived analytical solution for a single pillar located symmetrically in a mined-out void. Comparison of the analytical and numerical results shows their admissible precision.

The authors have revealed features of local methane concentration minimums in undermined degassing holes and causes of their zonality. The offered hypothesis on methane emission in underground wells accounts for zonal disintegration of rock mass around a stope.

It is known that under certain conditions, the structural geology, seismic, design and technology factors do not inhibit increase in the inclination of the limit pitwalls in deep open pit mines. The evaluation of the limit pitwall stability is made by the pitwall stability index, considered in ideal case. In practice, , which flattens pitwalls, expands the open pit mine limits on the surface and expands stripping. Therefore V.N. Sytenkov has proposed to construct a convex pitwall with the depth-wise decreasing stability index. It is assumed that when an open pit mine reaches its design depth and depletes its design reserves, the open pit mine stability coefficient cannot exceed 1. The article shows that this approach has both economical and physical preconditions.

The article reviews analytical methods of studying heat transfer processes running in the conditions of resource-saving underground coal processing, heat drying in processing facilities and in the course of heat accumulation and emission in caved rocks. The author considers problems with boundary conditions formulated at the moving boundary of the heat transfer domain.

The developed procedure for selecting parameters of positive-displacement hydropercussion systems has two stages. The first stage is the picking of the key parameters; the second stage is the engineering design of the system, adjustment of the selected parameters using the multivariate optimization procedure and the improvement of the system performance.

Based on the mine investigations of directional hydraulic fracturing using the bidirectional sealing device, aimed at weakening of a dirty band in a coal bed, the researchers have refined the valve synchronizer and eliminated detected vibration defects. The article presents the laboratory analysis of the KS-1 valve synchronizer operation and validates its efficient performance parameters.

The authors analyze excitability of polyharmonic vibrations in a single-body vibration machine. The developed mathematical model of the vibration system accounts for an elastic component element included in the design of the unbalance vibration exciter drive. The operating limits, frequency content and effect of the main design factors on the flow data of the vibration machine are examined. It is found that superharmonic vibration greatly contributes to the polyharmonic spectrum at certain frequencies, depending on the stiffness of the elastic component element of the clutch connecting the vibration exciter and the rotary drive.

The article gives analytical review of the mining and dressing waste situation and the experience gained in the waste exploration and reprocessing in Russia. The authors offer a new procedural approach to the appraisal and calculation of the mining and dressing waste accumulations with intent of their re-processing. The approach has been tested under conditions of diamond-containing mining and dressing waste sites.

The developed technology for thick and very thick flat ore body mining combines a number of mining methods using various ground control techniques. The regular patterns of stress distribution in the geotechnology elements are found. Analysis of rock mass stability yields the safe application range for the proposed geotechnology.

The upside potential of an underground mine ventilation by return air systems is analyzed in the article. It is shown that subsidiary air supply depends on the ratio of the pressure head of a recirculating draught producer to the mine depression at the recirculating draught producer site. By calculation of the actual example, the authors prove that air leaks can cause emergencies due to drastic reduction of fresh air supply in working areas.

The article discusses a new approach to implementation of the geoinformation environment for the mining geoinformation science problem solution using cloud technologies. In focus are the types of the cloud service as applied to the distributed geomonitoring networking for the wider range problem handling in mining. The authors describe specific structures of software support of the offered approach and exemplify problem solution in various spheres of mining geoinformation science.

The timely character of the digital space data utilization for regional and local day-to-day assessment of the environmental situation in the area of surface / underground mines and processing plants is proved. The natural environment situation is analyzed in terms of the Sorsky copper-molybdenum opencast mine (Republic of Khakasia, Russia).

By the analysis of oleinic acid flotation of fluorite and hematite, it is inconsistent to use thermodynamic approach to explain the flotation effect by the chemical adsorption of the reagent only. The authors propose a hypothesis that collecting ability of a flotation reagent relates with the activity of its physical adsorption at the air-liquid interface. The hypothesis is supported with the data on flotation of rutile, zircon and fluorite. Capability of surface pressure of film generated by molecules or ion-molecule associates as the criterion of collecting ability of a flotation agent is defined.

The authors describe experimental research findings on chemical-electrochemical leaching of gold from rebellious minerals. A laboratory-scale plant has been designed for studying the leaching kinetics. Rational parameters of chemical-electrochemical leaching are specified (duration of the process, electrode current density, NaCl concentration). The researchers analyze the changed microstructure and phase composition of arsenopyrite surface after the leaching and substantiate the leaching improving practices.

The studies into the fine-ingrained high-carbonate fluorite ore concentration show that increasing of pulp dispersion uniformity results in higher selectivity of flotation. The researchers find out availability of quality fluorite concentrate in processing of low-grade ore with carbonate index less than 1 CaF ₂ recovery up to 70%.

The actual safety regulations elide dynamics of air and gas conditions and their probabilistic nature, which results in underutilization of options of the advanced air and gas control in mines. The article proposes the decision-making using statistics filters, based on estimations of amplitude and duration of blow-outs. The authors derive relations for calculating the rational discrete intervals of explosimetric sensor sampling.