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Radiofrequency (5.28 MHz) electromagnetic radiation and low-temperature plasma were applied as short-term (2-15 min) seed treatments to two perennial woody plant species, including Smirnov's rhododendron (Rhododendron smirnowii Trautv.) and black mulberry (Morus nigra L.). Potential effects were evaluated using germination indices and morphometry. The results suggest that treatment with electromagnetic field stimulated germination of freshly harvested R. smirnowii seeds (increased germination percentage up to 70%), but reduced germination of fresh M. nigra seeds (by 24%). Treatment with low-temperature plasma negatively affected germination for R. smirnowii, and positively for M. nigra. The treatment-induced changes in germination depended on seed dormancy state. Longer-term observations revealed that the effects persisted for more than a year; however, even negative effects on germination came out as positive effects on plant morphometric traits over time. Treatments characterized as distressful based on changes in germination and seedling length increased growth of R. smirnowii after 13 months. Specific changes included stem and root branching, as well as increased leaf count and surface area. These findings imply that longer-term patterns of response to seed stressors may be complex, and therefore, commonly used stressor-effects estimates, such as germination rate or seedling morphology, may be insufficient for qualifying stress response. Bioelectromagnetics. 37:536-548, 2016. © 2016 Wiley Periodicals, Inc.

The authors have studied the physicochemical properties of aqueous dispersions containing carbon, silver, and iron nanoparticles which were produced by elastic-spark synthesis under the conditions of subaqueous spark discharge, and also the influence of preliminary acoustic and high-frequency electromagnetic action on them and the change in the functional indices of the glass-ionomer cement tempered by these dispersions.

The dynamics of the gas mixture in the cylindrical resonator of a CO2 laser with periodic heat release in the region of its axis was defined on the basis of the numerical solution of the system of Navier–Stokes equations by the explicit MacCormack method with splitting of the initial operator in space directions. The space fields of the gas-dynamic functions of the gas mixture and the ranges of their change were determined, and the character of the averaged flow of this mixture was investigated.

This paper presents the results of experimental studies of the influence of a high-frequency electromagnetic field on the physical, mechanical, and tribological properties of polymer friction composites for automotive brakes. It was shown that, in some cases, the treatment with an electromagnetic field results in the transformation of the polymer supramolecular structure. In the case of treatment of initial powder compositions, significant changes (up to 20%) in the dynamic modulus of elasticity and the tribological properties of the final materials were found. The possible mechanisms of the effect of pulsed high-frequency electromagnetic treatment on the physical and mechanical properties of friction materials, as well as the correlation of the properties with the acoustic noise of friction units, are under discussion.

Optical spectroscopic techniques are used to study the spectral and energy characteristics and to determine the gas temperature of rf discharges for treating cereal and legume seeds. It is shown that active plasma particles produce a change in the morphology of seed coats. The optimal conditions for plasma processing prior to planting, such that its biological effectiveness is greatest, are realized for a specific discharge power of ~0.35 W/cm3 and an exposure time of 5–7 min.

We have studied the effect of shallow modulation of the discharge current on the burning regime and the plasma parameters of a diffusion-cooled glow discharge in CO2/N2/He laser gas mixtures. We have established that modulation of the discharge current leads to excitation in the discharge of pulsations in the acoustic pressure, the electric current, and the intensity of the generated laser radiation, with the frequency of standing acoustic waves arising in the discharge tube and also with the frequencies of the current modulation, its harmonics, and combinations of all these frequencies with the frequency of the current pulsations in the power supply. We have shown that when self-sustaining resonant oscillations in the discharge current are excited or when the current is modulated, the IR luminescence intensity from the upper laser level of the CO2 molecule and the power of the radiation generated by the laser vary because of plasma heating in the positive column of the discharge, due to its contraction in the acoustic wave field initiated by the current pulsations.

We have studied the effect of the regimes of high-frequency (radio wave) electromagnetic treatment of gauging water on the process of structurization and on the technological characteristics of portland-cement systems. It has been established that the radio wave electromagnetic activation of water leads to a reduction in its surface tension, dynamic viscosity, and shear stress, as well as intensifies the formation of coagulation structures in a portlandcement slurry and aids in increasing the mobility of cement-sand mixtures.

The change in the structure of M1 copper on exposure to a nonequilibrium low-temperature plasma produced by a high-frequency capacitive discharge in air at a pressure of about 1 Torr was investigated. The influence of the duration of plasma action on the structure and mechanical properties of copper has been studied. The increase in the dispersity of copper and in the homogeneity of its structure under the action of plasma has been established. It is shown that transformation of the copper structure is accompanied by the formation of static distortions of its crystal lattice at a level of about 0.007∙10–10 m.

The results of studying the effect of high-frequency magnetic-pulse treatment of electrodeposited chromium coatings on their structure are described. It is shown that the effect of magnetic-pulse treatment depends on the deposition conditions, which are responsible for significant changes in the initial structure and microhardness of the coatings.

Variations in spectral coefficients of specular reflection and Raman scattering spectra were detected during exposure of a cast-iron surface to an electromagnetic field in the radio-wave range. The observed variations were supposed to be caused by both field-induced changes in the surface morphological structure, density, and crystalline state and ordering of the carbon structures accompanied by a reduction in the amount of defects. Spectral reflectometry and Raman scattering methods were shown to be applicable to nondestructive remote monitoring of the morphological state of the cast-iron surface and changes in the structure and size of its microcrystalline graphite inclusions.

We have investigated the influence of the regimes of high-frequency magnetic-impulse and acoustic action on the physicochemical properties of water solutions of polycarboxylate superplasticizers and technological indices of fine concretes plasticized by them. The dependences of technological properties of concretes on the concentration of water solutions of the superplasticizers, the content of impurity ions in the water used for dilution, and the conditions of acousto-radiowave treatment have been determined. The regimes of activation of superplasticizer solutions, which permit increasing the mobility and keeping quality of concrete and solution mixes tempered with water and the density and strength of fine concretes formed from them, have been established.

ISO brightness, fluorescence spectra, and the fluorescence integrated intensity of papers from domestic and foreign manufacturers were studied. The contrast index of the tested paper samples, which is defined as the ratio of the ISO brightness to the paper integrated fluorescence intensity in the spectral range from 380 to 700 nm, was estimated. An alternative method for controlling the paper background fluorescence level was proposed.

Comprehensive optical spectroscopic studies of the combustion process of solid-state pyrotechnic mixtures based on Mg and Sr(NO3)2 have been carried out. Emission spectra of the mixtures in the ultraviolet, visible, and infrared wavelength regions have been studied under various atmospheric conditions taking into account radiation transfer in air along an optical path of observation up to 5 km long.

The effect of the complex acoustic-radio wave treatment of water on the index of activity of the hydrogen ions, the rheological characteristics of the cement-sand mixtures tempered by this water, and the technological parameters of the obtained plasticized fine-grained concretes was studied. Two methods were used to reach the maximum effect on the index of the activity of the hydrogen ions of the water, the mobility, the storability of the prepared concrete mixes, and the density and compressive strength of the concretes. The first method was a four-minute complex acoustic-radio wave treatment of the water (high frequency (5.28MHz) + ultra sound (44 kHz)) that was followed by the four-minute additional impact of a high-frequency field. The second method used was a four-minute complex treatment of used water (high frequency (5.28 MHz) + ultra sound (1 MHz)) followed by the two-minute extra impact of a high frequency field. The assumptions concerning the mechanism of the acoustic-radio waves activation of the water and the effect of this water on the process of hardening used and the structure of the Portland cement systems are expressed.

The variation in the structure and properties of cast-iron sealing rings (content in wt %: 2.8–3.0 Si; 0.4–0.6 Mn; 0.1–0.2 Cr; 0.5–0.6 Ni; 0.7–0.9 Cu; 0.04–0.06 Mg; 2.8–3.0 C) under their exposure to a 5.28-MHz pulsed magnetic field is studied. Variations in the eutectoid morphology, the internal structure of the graphite inclusions, and the size of the free cementite inclusions, which result in the enhancement of the hardness, are observed. The magnetic-pulse treatment of rings induces compression stresses in them. The physicomechanical properties of the rings change periodically upon the variation of the number of treatment cycles. The optimum mode corresponds to two cycles.

The influence of the time of treatment of the tap and distilled water used for tempering of plasticized fine concretes by a high-frequency magnetic field on the technological characteristics of these concretes was investigated. The optimum regimes of treatment of the mixing water by this field and the dependence of the properties of the concretes obtained with it on the time of its storage after the treatment were determined.

The effect of a low-intensity radio wave (5.28 MHz) electromagnetic field on the seeds of annual and perennial legumes has been investigated. It has been shown that the presowing electromagnetic treatment of the seeds with a duration of 10–15 min contributes to their laboratory and arable germination enhancement, survival, and crop capacity increase and can be considered as a mediator of the seeds’ cell receptors that initiate intracellular mechanisms that lead to the improvement of the seeds’ sowing quality.

The bactericidal action of the plasma of a high-frequency discharge excited at a frequency f = 5.28 MHz and a low pressure in air on different test-strains of microorganisms has been investigated. The high-efficiency plasma inactivation of strains of E. coli, B. subtilis, C. albicans, and S. aureus at an initial contamination N 0 ≤ 103 CFU / ml was detected. It was established that the most probable sterilization agents of the plasma generated are the “hot” and “cold” OH radicals, the excited electrically neutral N2 and O2 molecules, and the UV plasma radiation.

The space-time structure of fast jets flowing out from the cumulative groove of the detonating charge of a brisant explosive has been investigated. The velosity field of the jet and the flow of detonation products have been determined. We have revealed a change in the structure of the front end of the jet followed by an increase in its luminescence intensity and a decrease in the efflux velocity upon introduction into the cumulative groove of mixtures of metals and graphite. The sizes of the jet inhomogeneities reflecting the spatial scale of zones of selective change in its thermodynamic parameters have been estimated.

It has been shown that digital dynamic speckle photography is an effective method for quantitative diagnostics of changes in the structure of paper processed by pulsed discharge. A theory of the dynamic statistics of speckle fields and mathematical relations are given. In using optical magnification \(\mathfrak{M}\) = 1, the software developed permits fast statistical processing of up to 250,000 microzones in a two-dimensional CCD image of size 20 × 30 mm. The results obtained point to a high spatial and temporal resolution of the method and the possibility of its real-time realization. It has been shown that noise filtering is an important part of speckle image processing. The software permits filtering both in direct calculation of the correlation function and in the Fourier plane with the use of the fast Fourier transform.

We have used laser Stokes polarimetry to study changes in the structure of paper for offset printing when exposed to a high-frequency electromagnetic field. We have shown that the effect of a high-frequency electromagnetic field on paper appears as a decrease in the structural ordering of the material and a change in the shape of the indicatrix of the reflected radiation power from an He-Ne laser at the wavelength 632.8 nm, a decrease in the bidirectional reflection and transmission coefficients of the paper. We have established that when the force lines of the magnetic component of the high-frequency electromagnetic field are oriented perpendicular to the plane of the sheet of paper, we observe a more substantial decrease in the anisotropy in the surface layer and within the interior (the volume) of the paper than when the lines of force are oriented parallel to the plane of the paper.

A capacitively coupled planar rf discharge in CO2/N2/He gas mixtures at pressures up to 50 Torr is investigated using optic emission spectroscopy methods. The spatial distribution of the gas kinetic temperature has been measured and the mechanisms of the heating of plasma’s neutral component in various zones of the electrode gap have been considered. The influence of small additives of water vapor on luminescence intensity and plasma parameters is also discussed.

An automated spectral complex for controlling the parameters of the plasmachemical‐reactor working medium by the emission and absorption spectra in the 200–1100‐ and 2000–5000‐nm ranges has been developed. To record radiation, a CCD array and a pyroelectric detector are used. Control of the spectral device functions, data recording, and the obtaining of results reflecting the working‐medium parameters and the concentration in it of components being measured are carried out by means of a personal computer. The complex makes it possible to study the temporal behavior of the working‐medium parameters being measured with a resolution of up to 10−2 sec.

Using the methods of emission spectroscopy, we studied the influence of generated radiation on heating the active medium of a fast-flow electric-discharge CO2 laser.

The optical radiation spectra and the spatial structure of a planar high‐frequency capacitive discharge in N2/CO2/He gas mixtures have been investigated depending on the excitation frequency, discharge current, pressure, and chemical composition of the mixture.

The possibility of using a multijet electric arc plasma‐chemical reactor for decontamination and destruction of different powder pesticides with an expired effective date and storage life which have not been used in agriculture is studied. Studies of heat transfer are conducted on a setup operating without processing of raw material and with supply of pesticides (isophen and butyl ester of 2,4‐dichlorophenoxyacetic acid) to the reactor. The composition of waste gases at the reactor outlet is studied.

Using methods of emission spectroscopy, we have determined the gas‐kinetic temperature fields of planar high‐frequency capacitive discharge plasma in N2/CO2/He gas mixtures depending on the excitation frequency, discharge current, pressure, and chemical composition of the mixture. It is shown that the dominant contribution to the neutral component heating in the center of the discharge chamber is made by the processes of V–T relaxation of vibrationally excited molecules N2(X1Σ, V″) and CO2(X1Σ, V″), whereas in the zones near the electrodes an important role in the heating is played, along with the V–T relaxation of the N2(X1Σ, V″) and CO2(X1Σ, V″) molecules, by the processes of deactivation of the metastable states A3Σ of the N2 molecule.

Based on investigating the spatial distribution of the radiation intensity in molecular bands of nitrogen ions the authors determined the widths of the layers of positive space charge in mixtures of molecular gases in transverse HF excitation. It is shown that contrary to predictions of the elementary theory these widths depend relatively weakly on the excitation frequency and the gas pressure.

Emission spectroscopy methods were used in an investigation of thermodynamic parameters of a surface plasma formed by the action of cw CO2 laser radiation of (2–5)×106 W cm-2 intensity on stainless steel in a protective He or Ar atmosphere. The spatiotemporal structure and pulsation characteristics of the plasma plume were used to determine the fields of the plasma electron density and temperature.

An influence of RF plasma and RF electromagnetic field pre-treatments on level of fungal infection of some important agricultural plants has been studied. It is shown that pre-sowing plasma and radio-wave seeds treatments contribute to their germination enhancement and plant productivity improvement owing to stimulative and fungicidal effect of plasma and RF electromagnetic field irradiation.

In the present paper a gas kinetic temperature change of active medium of high-power TEA CO 2 laser that is conditioned by a self-influence of laser radiation on plasma parameters, is investigated. The active medium was pumped by a self-sustained transverse glow discharge. The gas kinetic temperature T g of plasma has been deduced from the half-width of rotationally unresolved spectral bands of the (2+)N 2 . It is shown that the laser radiation propagation through the inverse medium causes a cooling of the active medium. The degree of the gas mixture cooling δTg≈5K at W~2.2 W/2.2 W/cm 3 and δTg≈60 K at W~4.4 W/cm 3 . We suppose that the effect of the active medium cooling is connected with the change of a kinetic of V-T relaxation in asymmetrical mode of the active medium cooling is connected with the change of a kinetic of V-T relaxation in asymmetrical mode of the active medium cooling is connected with with the change of a kinetic of V-T relaxation in asymmetrical mode of vibrationally-excited CO 2 molecule when the lasing takes place in the laser resonator. Analytical estimation of light-induced temperature change δT* g of fast-flow TEA CO 2 -laser active medium are compared with the experimental ones.

The spectroscopic parameters of transversal RF discharge in gas mixtures CO2 + N2 + He are investigated. It hasbeen observed that the width of the shields in a capacity RF discharge in such mixtures is almost independent on thefrequency of RF field; it sufficiently differs from the theoretical predictions. The spatial distribution of the neutralgas temperature in various gas mixtures has been measured and discussed. The influence of the small additives ofwater vapour on luminescence intensity and its spatial distribution is also discussed.Keywords: Radio frequency discharge, temperature spatial profile, space charge 1. Introduction The high-frequency capacitive discharge (RFCD) at average pressure is widely used in a lot of various practicalapplications. Recently it has been reached a great progress in an engineering of electrical discharge CO2 lasers with RFpumping as well as in the plasma-chemical reactors designing. For successful development of these devices and otherfields of application it is necessary to have an adequate model of RFCD plasma. It, in turn, demands a reception of newexperimental data about the features of RF discharge in various conditions; for instance, a spatial structure and spectralparameters of the planar RFCD plasma in molecular gases are not yet satisfactory investigated. In our previous works

The outcomes of spectroscopical investigations of RF-discharge plasma parameters are represented for the CO2 laser mixtures. The main emphasis is made on the exploration of spatial instabilities of luminescence intensity and gas temperature distribution in such discharge. Unlike the theoretical prediction it is shown that sizes of the sheath in a RF discharge weakly depend on excitation frequency and gas pressure.© (2000) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Optical and spectroscopic methods were used in studying near-surface plasma that is formed under the effect CW CO2 laser of (2- 5)x106W/cm2 power density upon stainless steel in He and Ar shielding gases. The variation of plume spatial structure with time has been studied, the outflow of gas-vapor jets from the interaction area has been characterized. The spectra of plasma plume pulsations have been obtained for the frequency range Δf = 0-1 MHz. The temperature and electron concentration of plasma plume have been found under radiation effect upon the target of stainless steel. Consideration has been given to the most probable mechanisms of CW laser radiation-metal non-stationary interaction.© (2000) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

A qualitative analysis of the role of some hydrodynamic flows and instabilities by the process of laser beam-metal sample deep penetration interaction is presented. The forces of vapor pressure, melt surface tension and thermocapillary forces can determined a number of oscillatory and nonstationary phenomena in keyhole and weld pool. Dynamics of keyhole formation in metal plates has been studied under laser beam pulse effect ((lambda) equals 1.06 micrometers ). Velocities of the keyhole bottom motion have been determined at 0.5 X 10 5 - 10 6 W/cm 2 laser power densities. Oscillatory regime of plate break- down has been found out. Small-dimensional structures with d-(lambda) period was found on the frozen cavity walls, which, in our opinion, can contribute significantly to laser beam absorption. A new form of periodic structure on the frozen pattern being a helix-shaped modulation of the keyhole walls and bottom relief has been revealed. Temperature oscillations related to capillary oscillations in the melt layer were discovered in the cavity. Interaction of the CW CO 2 laser beam and the matter by beam penetration into a moving metal sample has been studied. The pulsed and thermodynamic parameters of the surface plasma were investigated by optical and spectroscopic methods. The frequencies of plasma jets pulsations (in 10 - 10 5 Hz range) are related to possible melt surface instabilities of the keyhole.

An interaction ofthe CW CO2 laser beam and a moving metal surface has been studied. The pulsed and thernzodynamical parameters of the surface plasma were investigated by optical and spectroscopical methods. The subsonic radiation wave propagation in the erosion plasma torch has been studied. 1. INTRODUCTIONThe investigations of CO2 laser beam materials interaction are practically important in laser - materials processing R&D. The processes of CW laser beam deep penetration welding, when laser beam power density is of order of 1>2 106 W/cm2 are being used in many applications [1]. These processes are accompanied by intense evaporation ofthe welded material and by low-threshold optical breakdown (LOB) of the metallic vapor and the assist gas. This LOB causes the beam defocusing and consequently the welding depth [2]. The LOB plasma influence on CW CO2 laser beam-metals interaction with I>2 106 W/cm2 is insufficiently studied [3, 4]. Present contribution is devoted to a complex study of pulsed

A paper for offset printing was exposed to radio frequency discharge plasma and radio frequency electromagnetic field. Optical response and structural features of paper before and after the treatment have been investigated by several techniques: digital laser speckle photography, laser Stokes polarimetry and attenuated total reflectance (ATR). The changes of statistical distributions of speckle patterns has been observed for plasma treated paper as a result of increase of correlative dimensions of structural heterogeneity of modified paper. It is shown also that the radio wave treatment leads to anisotropy reduction in the paper structure that is more apparent if the magnetic field lines are oriented transversely to the plane of a paper sheet.

The influence of an external acoustic field on the temperature of an air-discharge plasma in the channel of a sectional plasmatron is investigated.

Bands of the sequence &V = --2, --3, --4 of the second positive system of nitrogen N~(2+) were used in the capacity of the pyrometric component when studying glow discharge in sealed or weakly permeable tubes [6, 7]. The present work examines the usefulness of MURS for operational monitoring of the gas temperature in a glow discharge in an atmosphere of nitrogen with a pumping rate v through an interelectrode gap of ~i00 m/sec at an operating pressure of p > 1.33 kPa. The need for similar studies is caused by lasers being used in technology which have separate excitation of the gain medium's components [8] along with closed cycle CO2-EDL's. The merit of identifying the rotational temperature Tro t with the gas temperature Tg follows from the relationship between the rotational relaxation time TR-T [9-11] and the lifetime ~c of the C3Eu of nitrogen allowing for its deactivation due to collisions with other molecules [12]. For p = 1.33 kPa in correspondence with the data of [9-12], Tc/TR_T - i0, i.e., in the course of rc = 40 nsec rotational--translational relaxation does not take place and a Boltzmann distribution of the molecules is established in the CSHu state with respect to the rotational levels with a temperature Tro t = Tg. The validity of the proposition just made is demonstrated experimentally in [13].

The solution of several problems of high-temperature radiation gas dynamics requires information on the emission and absorption coefficients of a plasma over a wide wavelength range with high spectral resolution. The plasma sources most widely used for the experimental determination of these parameters are stabilized electric arcs [I-4]. In contrast to shock tubes and ultrasonic ballistic setups, as a result of the spatial inhomogeneities of the plasma column they provide simultaneously experimental information on the emission coefficients of the plasma at different temperatures.