Background. The work is devoted to the problem of evaluating the effectiveness of extinguishing open fires of solid combustible substances and materials, as well as internal (closed) fires (if it is impossible to ensure the sealing of the protected volume) by gas fire extinguishing installations when using gas extinguishing agents with special physicochemical properties. The aim of the work is to develop an analytical model for evaluating the effectiveness of extinguishing fires of solid combustible substances and materials with gas extinguishing agents having special physico-chemical properties, taking into account the dynamics of internal (closed) and external (open) fires and the intrinsic electrophysical properties of the flame. Materials and methods. Mathematical models of polarization of electron displacement, as well as ionization by electron impact of gas dielectrics are used in the work to determine the values of the velocity and cross-section of dissociative recombination, and as a consequence, estimation of the time of extinguishing the fire. Results. The physical mechanism of the extinguishing effect of gas extinguishing agents and their mixtures is substantiated, comparative quantitative estimates of the values of the time of the flame flare from the surface of the combustible substance are given, the values of the fire extinguishing time based on the comparison of the values of concentrations and energies of the electronic component during the process of dissociative recombination, accompanied by the decay of the intermediate complex, in the flow of extinguishing agent and flame torch in a stationary combustion mode. Conclusions. A necessary and sufficient condition for extinguishing fires of solid combustible substances and materials with gas extinguishing agents having special physico-chemical properties is the intensification of the rate of dissociative recombination occurring in the structure of flame flare zones when an electronic component of a gas extinguishing agent, polarized and ionized in an external static electric field, is introduced into the fire source. Also, the work shows a relatively higher efficiency of applying an external longitudinal static electric field to the flow of the extinguishing agent, which is due to higher concentrations of the electronic component in the electrode gap.

The article is devoted to the problem of studying the electrical properties of a flame in a fire. The article discusses a method for measuring the active electrical resistance of a diffusion flame when burning liquid combustible substances. The dependence of the electrical resistance of the flame torch on the geometric dimensions of the combustion zone and on the average volumetric temperature of the flame torch in the mode of the laminar flow of the combustible mixture has been established. An empirical dependence has been obtained, which makes it possible to calculate the value of the electrical resistance of the flame.

New socio-economic conditions for the development of Russia dictate new requirements for the protection of buildings, equipment and personnel of various facilities from fires and their consequences. In complex fire extinguishing systems, the timeliness of fire detection and the effectiveness of extinguishing is the key to preserving material values and human lives. An urgent task is not only the improvement of existing fire extinguishing systems, but also the development of new systems, the basis of which is based on previously unused approaches. These approaches are based both on the previously known physical and chemical methods of extinguishing fires, and on the methods being investigated and studied at present. One of the promising methods of extinguishing fires is the technology of extinguishing fires using the effect of an electromagnetic field on the diffusion flame. The study of this method involves the analysis of physical processes that are electromagnetic in nature of interaction occurring in the system “diffusion flame torch - electromagnetic wave”. In this work, a quantitative analysis of the parameters affecting the possible mechanisms of interaction of the elements of this system is carried out. A mathematical model of the considered physical processes is presented.

An approach to separate the metallic and dielectric losses in ferroelectric capacitors in all range of tuning under control dc voltages (U-dc) is considered. The procedure is based on measurements of the dc voltage dependencies of microwave losses (tan delta(t)(U-dc)) and capacitance (C(U-dc)) for a set of capacitors with similar layout but with different nominals. Linear extrapolation of tan delta(t)(C) dependencies at different control dc voltages to C = 0 allows to evaluate the dielectric losses tan delta d as a function of the control dc voltage. The procedure of separation was performed for a set of sandwich metal/(Ba0.5Sr0.5) TiO3/metal capacitors. Capacitors parameters were measured at a frequency of 2 GHz in a range of electric field strength in ferroelectric of E = (0 - 30) V/mu m. The intrinsic commutation quality factor of BSTO film itself was estimated by the method proposed.

A ferroelectric BaxSr1−xTiO3 (BSTO) thin film structure on a diamond substrate was developed for the first time to reduce an overheating in high power microwave applications. The BSTO/SiC/Diamond structure was produced by ion-plasma rf magnetron deposition technique with a silicon carbide (SiC) layer as a buffer to compensate the thermal expansion difference between the BSTO film and the diamond substrate. It was shown by an X-ray diffraction and Rutherford back-scattering analysis that the thin SiC crystalline buffer layer provides the growth of the (100) oriented BSTO perovskite films with good adhesion. The BSTO planar microwave capacitive elements were investigated at a frequency of 3GHz and the non-linear dielectric response of the BSTO capacitor on SiC/diamond substrate was demonstrated based on the temperature and voltage dependencies of the capacitance. The overheating of the BSTO/SiC/diamond capacitor under exposure of high level microwave power was observed to be an order of magnitude lower than that for the capacitors on Al2O3 substrate.

We have fabricated the 1.3-1.55 um PIN photodetector based on InGaAs/InP heterostructure. Measurement results of optical and electrical characteristics of PIN photodetector chip were the following: photoconductivity at 1550 nm was 0.65 A/W and internal capacitance was 0.025 pF. Microwave model of photodetector was developed and verified by measurements of scattering matrix. The implementation of broadband (up to 20 GHz) hybrid integrated matching and biasing circuit for high-speed photodetector is presented.

The possibility of radical increasing the output mm-wave power of the tripler (20 GHz/60 GHz) due to use of planar ferroelectric varactor is considered. A theoretical analysis of a planar ferroelectric varactor potentiality for frequency triplers is presented. The analytic expression for the tripler conversion efficiency is derived and proved by computer simulation of the output tripler parameters using experimental data on Ba 0.3 Sr 0.7 TiO 3 film nonlinearity. Thermal conditions and nonlinear behavior of the FE varactor being under the exposure to high input microwave power is analyzed. It is demonstrated that the output power of ~ 26dBm (corresponding to maximal conversion efficiency of 17%) can be obtained for 20 GHz/60 GHz tripler based on the planar ferroelectric varactor (Ba x Sr 1-x TiO 3 film on the diamond substrate).

Three types of an impedance matching circuits (MC) namely resistive, reactive and tunable reactive MC (TRMC) are analyzed to estimate the advisability of their application for directly modulated lasers (DML) in microwave (MW) photonic systems. Return loss (|S 11 |) and insertion loss (|S 21 |) frequency dependencies for MCs loaded by a DML are calculated for X-band broadly used in radar systems. Analysis of the TRMC characteristics is carried out taking into account the microwave parameters of tunable elements of different classes (semiconductor, ferroelectric and micro-electromechanical (MEM) elements). It is shown that in the instantaneous frequency band (Δf i ~ 1 GHz) the TRMC in comparison with the resistive MC provides more than 10 dB increase of the MW power delivered to an active region of the DML. Proposed TRMC demonstrate ~ 2.5 times increase of the total frequency operating bandwidth (Δf op ~ 5 GHz) due to a frequency scan possibility for the instantaneous band in contrast with the non-tunable reactive MC.

The surface morphology of aluminum alloys under irradiation by a high-power nanosecond ion beam with a low current density is investigated. The possible factors responsible for the change in the surface relief are considered.

A new design of electrically tunable multilayer structure (deflector) millimeter wavelength range based on the periodic structure of the ferroelectric/linear dielectric is proposed. Numerical simulation results show the parameters of the deflector increase efficiency of the deflection angle of the main beam of the radiation pattern due to the dispersive properties of the structure in comparison with existing analogues.

Using developed theoretical model of mode synchronization in semiconductor passively mode locked laser (PMLL) we have calculated influence of length and relaxation rate of saturable absorber (SA) on operation regimes of PMLL. We included in consideration the influence of emission rate of free carriers from the levels of dimensional quantization in the SA and found out the optimum operating voltage for PMLL in the fundamental synchronization mode (one harmonic component) as -1.5 - -2 V with optimal length of the SA as 0.637 mm.

Thin ferroelectric Ba x Sr1–x TiO3 (BST) layers have been grown for the first time on semi-insulating silicon carbide substrates by RF magnetron sputtering of a ceramic target without using buffer sublayers. Results of investigation of the structure of obtained BST films and the electrical properties of related planar capacitors are presented. The obtained structures are characterized by high nonlinearity and low dielectric losses at microwave frequencies.

A method of ion plasma deposition is proposed for obtaining thin multicomponent films with continuously graded composition in depth of the film. The desired composition–depth profile is obtained by varying the working gas pressure during deposition in the presence of an additional adsorbing screen in the drift space between a sputtered target and substrate. Efficiency of the proposed method is confirmed by Monte Carlo simulation of the deposition of thin films of Ba x Sr1–x TiO3 (BSTO) solid solution. It is demonstrated that, during sputtering of a Ba0.3Sr0.7TiO3 target, the parameter of composition stoichiometry in the growing BSTO film varies in the interval of x = 0.3–0.65 when the gas pressure is changed within 2–60 Pa.

We consider a method of control over the operating frequency of a resonator on bulk acoustic waves, which is based on the selective excitation of eigenmodes. The frequency switching is achieved by using several layers of a ferroelectric in the paraelectric state and applying a control voltage of appropriate magnitude and polarity to each layer. The principle of selectivity is formulated and the criterion function is defined, which ensure the most effective excitation of a selected eigenmode with the possible suppression of parasitic modes. An example of using this function for a resonator switched between four eigenmodes is presented.

Исследовано изменение морфологии и состава поверхности медных сплавов (латунь Л63, бронза ВБ23НЦ, сплав Cu–Al), содержащих компоненты с различной летучестью при воздействии мощного ионного пучка наносекундной длительности. Показано влияние различных компонентов сплавов на формирование кратеров на поверхности при таком воздействии. Рассмотрены возможные механизмы наблюдаемых явлений.

Changes in the morphology and surface composition of copper alloys (L63 brass, VB23NTs bronze, and a Cu-Al alloy) containing components with different degrees of volatility, under the action of a high power ion beam of nanosecond duration, are investigated. It is demonstrated that various alloy components affect the formation of surface craters during ion beam irradiation. The probable mechanisms of the observed phenomena are discussed.

Structural and phase transformations in copper and its alloys—brass and bronze, irradiated by a high-power ion beam are investigated by X-ray diffraction and scanning-electron microscopy. It is established that the phase reconstruction in brass is caused by the partial removal of zinc from the surface and its diffusion toward the surface from deeper surface layers. Copper and bronze undergo only structural transformations induced by the growth of stresses of type I, II, and III and dislocation density.

С помощью методов рентгеновской дифрактометрии и растровой электронной микроскопии исследованы структурно-фазовые изменения, происходящие под действием мощного ионного пучка в меди и ее сплавах – латуни и бронзе. Обнаружено, что фазовая перестройка в латуни связана с частичным удалением цинка с поверхности и диффузией его к поверхности из более глубоких приповерхностных слоев. В меди и бронзе происходят только структурные превращения, вызванные возрастанием напряжений I, II и III рода и увеличением плотности дислокаций.

The change in the composition of the surface layers of brass LS59-1 and bronze BrOS10-10 under the action of a high power ion beam has been studied. Zinc depletion of the brass surface at a beam current density of j ∼50 A/cm2 is shown; zinc enrichment of the surface layer is observed at j > 150 A/cm2, and a thin zinc layer is found to be formed across the entire surface. For bronze BrOS10-10, tin enrichment of the surface is registered only under a multiple effect of the beam at j >150 A/cm2. Various mechanisms of modifying the elemental composition are considered.

The change in the morphology and surface composition of copper alloys (brass LS 59-1, bronzes BrOS 10-10 and BrAJ 9-4) upon irradiation with a high power ion beam of nanosecond duration is studied. It is shown that craters are mainly formed at the location of lead or sulfur inclusions. The reverse deposition of zinc onto the surface of brass is found. Possible mechanisms of these phenomena are considered.