Microwave Electromagnetic Field Research Articles

Destruction of water-in-oil emulsions in electromagnetic fields

In this paper, we study the degree of exposure of electromagnetic fields to water-oil emulsions with different physical and chemical properties, as well as the characteristics of their heating and delamination when exposed to radio frequency and microwave frequencies in electromagnetic fields. Experimental research methods are described. The results of experimental studies of heating emulsions in radio frequency and microwave electromagnetic fields under dynamic conditions and the results of their separation are presented. As a result of the research, it has been found that when exposed to radio frequency or microwave electromagnetic fields on oil-water emulsions, the degree of heating and the efficiency of emulsion stratification depend on the total content of asphaltene and resins, the water content in the emulsion, and the operating frequency of the generator in the region of resonant frequencies for emulsions. For all types of emulsions, radio frequency action is more effective than a microwave field, with low water contents. With increasing water content the efficiency of microwave exposure increases. Also, with an increase in the water content, the intensity of heating the emulsion in the microwave field increases with the same energy inputs.

Optimization Design of Fixed-Length Bond-Wire Interconnection in Multichips Module

This paper studies signal integrity problems caused by parasitic parameters and skin effect of bond wire. Based on the low-pass filter theory, this paper proposes a new design of bond-wire interconnection circuit in microwave multichip modules. The transmission characteristics of bond-wire interconnection circuit can be significantly improved when the length of bond wire is fixed. A compensation structure based on the third-order Butterworth low-pass filter is presented. In comparison with the uncompensated structure, the bandwidth of the bond wire is increased by 25.1 GHz with the proposed design. Moreover, a compensation structure based on the fifth-order Chebyshev low-pass filter is presented, too. In comparison with the uncompensated structure, the parasitic effects of the bond wire are minimized, and the bandwidth is increased by 56.8 GHz with the proposed design. The microwave circuit design software and electromagnetic field software were used to model and analyze the microwave characteristics of this circuit. The circuit was verified by the results of the simulation.

Effects of TiO2 Content on Microwave-Attenuating Properties of TiO2-Al2O3 Composite Ceramics

Microwave attenuation ceramic is a kind of dielectric loss material, which is used to absorb some unnecessary microwave electromagnetic field energy. For this attenuation material, it is required to have a large attenuation ratio, a sufficient mechanical strength and a good thermal stability. In this work, TiO2-Al2O3 composite ceramics were prepared via the conventional pressureless sintering method. The addition of CuO as liquid phase sintering aid was used to lower the sintering temperature of TiO2-Al2O3 composite ceramics. The effects of TiO2 content on sintering properties, phase composition, microstructure, mechanical properties and microwave-attenuating properties were investigated. With the increase of TiO2content, the sintering temperature decreased from 1300°C to 1100°C, meanwhile the dielectric constant rose from 15.42 to 23.80 and the dielectric loss increased from 0.042 to 0.314, which improved the attenuation of the TiO2-Al2O3 attenuation ceramics. When the content of TiO2 was 10 wt%, TiO2-Al2O3 composite attenuation ceramics with good properties could be obtained.

Temperature Assessment Of Microwave-Enhanced Heating Processes

In this study, real-time and in-situ permittivity measurements under intense microwave electromagnetic fields are proposed as a powerful technique for the study of microwave-enhanced thermal processes in materials. In order to draw reliable conclusions about the temperatures at which transformations occur, we address how to accurately measure the bulk temperature of the samples under microwave irradiation. A new temperature calibration method merging data from four independent techniques is developed to obtain the bulk temperature as a function of the surface temperature in thermal processes under microwave conditions. Additionally, other analysis techniques such as Differential Thermal Analysis (DTA) or Raman spectroscopy are correlated to dielectric permittivity measurements and the temperatures of thermal transitions observed using each technique are compared. Our findings reveal that the combination of all these procedures could help prove the existence of specific non-thermal microwave effects in a scientifically meaningful way.

Microwave heating in industry

The article presents an analytical review of publications highlighting the possibilities of innovative application of technologies using the energy of the electromagnetic field of ultrahigh frequency (EMF microwave) in various industries. As the analysis of technologies based on the action of the electromagnetic field of the ultrahigh frequency range shows, they are already used to solve a variety of problems: from sterilizing compotes and drying lumber to producing thermally expanded graphite and the use of these technologies in medicine. This article highlights the main advantages of using the microwave electromagnetic field, regardless of the scope of its practical application. The implementation of innovations, based on the energy of the electromagnetic field of the microwave range in the technological schemes of various industries will reduce energy consumption and improve the efficiency of the technological processes themselves. This implementation will ultimately lead to increased productivity and lower capital and operating costs, it will allow to significantly modernize production in terms of reducing energy consumption per unit of the processed product, and in terms of improving the quality of raw material processing. Possible deficiencies and their solutions in production processes are described. A significant obstacle to the intensive implementation of these technologies is the fact that the nature of wave propagation in different materials, under different initial and final conditions, can differ significantly from each other. This, in turn, implies careful design of the hardware component (emitters and chambers) as well as finding the optimal process parameters (temperature and heating rate, installation power, intensity, frequency and electromagnetic field intensity).

EFFECT OF MICROWAVE RADIATION ON STRENGTH CAPPED POLYMER COMPOSITION MATERIALS WITH LIGHTNESS PROTECTIVE RETAINED COATING LOW-CYCLE LOADING

ObjectivesThe analysis of the features of application of fiber-reinforced polymer composite materials (PCM) of different nature in the structural elements of aviation technology and methods of increasing the strength of their products.MethodIt is indicated on the positive effect on the strength of the bending stress and interlayer shear finish treatment of cured PCM in the microwave electromagnetic field. It is noted that the peculiarity of the elements of the skin of PCM is the presence in the surface layer of the built-in metal mesh, or lightning-proof coating (MFP), necessary to ensure the stability of structural elements to the effects of atmospheric electricity discharges.Result. The tests of the control and processed in the microwave electromagnetic field samples from PCM with MSP on low-cycle fatigue at the number of loading cycles-60 and strain amplitudes-10 mm. it was Found that in the control samples with the grid MEU primary crack appears after 6 cycles. After microwave processing, the samples retain their integrity, but the load causing the set deformation is reduced by 14% already on the 35th cycle.ConclusionDurability of samples with the heat-treated grid "Тekstilmash" and with a grid without heat treatment after influence of microwave electromagnetic field increases respectively by 59,5% and 71%. At the same time, the samples retain their integrity after 60 loading cycles, and the maximum stresses are reduced by 13.7% and 5.8%, respectively, compared to static tests. The limit of low-cycle fatigue increases after microwave treatment from 37 to 210%.

Portable neutron generator with microwave ion source for wide applications

The paper presents the issues related to the development of a portable neutron generator with a microwave source of heavy hydrogen ions for a wide range of applications. The paper analyzes the effect of electromagnetic microwave field strength and the magnetic induction value of a constant external magnetic field on the ionization rate of molecular deuterium and determines their optimal ratios. It also describes the configuration of the magnetic system of permanent magnets made of NdFeB material, which provide a homogeneous magnetic field with an induction of 850 Gs necessary for the effective operation of the device using the electron cyclotron resonance (ECR). The dynamics of the primary deuteron flux, as well as secondary particles in the ion-optical system are analyzed. Elements of a conceptual design of a portable neutron generator are described.

Electromagnetic Field Intensity Imaging by Thermofluorescence in the Visible Range

Methods to measure the electromagnetic field intensity on a large scale should be improved to meet the growing demand in civil and military applications. The recent development and an application of a microwave electromagnetic field imaging method using a thermofluorescent device and detection in the visible-light range are described. The sensor is a flexible film sensitive to either an electric field (slightly conductive film) or a magnetic field (insulating film with ferromagnetic particles) coated with a polymer doped with fluorescent molecules displaying temperature-dependent emission. We use a lock-in thermog-raphy protocol consisting of modulation of the field at low frequency, which allows us to suppress the noise due to heat-transfer phenomena and the part of the signal not directly related to field absorption. Two applications of the method are presented: (i) imaging the microwave magnetic field emitted by a resonator antenna and (ii) the local probe measurement of the electric field inside a multibeam antenna. The process to develop the sensitive film, its detailed characterization, and the thermofluorescence-image demodula-tion postprocessing are presented in detail. This approach is much cheaper than one based on infrared thermometry and could permit democratization of microwave-and radio-frequency electromagnetic field imaging.

Kinetic modeling of microwave extraction of polysaccharides from Astragalus membranaceus

Astragalus is one of the traditional Chinese herbs used for both medicine and food, and the extraction of polysaccharides from Astragalus is popular for its pharmacological activities. In this present study, a new theoretical kinetic model for microwave extraction of polysaccharides was developed by combining Fick's law with microwave electromagnetic field enhancement diffusion theory. Based on fitting to experimental data, a semi-empirical kinetic model was then established using multiple nonlinear regression, achieving a high determination coefficient (R2) of 0.9223. The semi-empirical model was used to provide more insights in microwave extraction and mass transfer mechanism of Astragalus polysaccharides. Astragalus cellular structures as affected by microwave extraction were also analyzed by scanning electron microscopy, revealing that the extraction was mainly due to the action of microwave-induced pressure in Astragalus cells, causing destruction of Astragalus cellular structure. Practical applications Astragalus is a traditional Chinese herb that can be used for both medicine and food. Extraction of polysaccharides from Astragalus is popular as Astragalus polysaccharide (APS) has high biological activity for reducing blood sugar, anti-oxidation, anti-virus, anti-tumor, anti-inflammatory, and enhancing immunity. Therefore, optimizing the extraction process plays an important role in enhancing extraction rate. In this study, kinetic models for microwave extraction of APS were established, scanning electron micrograph revealed that microwave treatment could generate Astragalus intracellular pressure, which caused destruction of the Astragalus cellular structure, thus improving the extraction efficiency. Results indicated that higher degree of Astragalus cellular structure damaged by microwave would lead to higher extraction rate of polysaccharide. The study would thus provide guidance for improving the microwave extraction process of polysaccharides from Astragalus for the industry.

STUDYING THE INFLUENCE OF MICROWAVE RADIATION ON THE THERMOPHYSICAL CHARACTERISTICS OF REVERSED POLYMER COMPOSITION MATERIALS REINFORCED BY CARBON FIBERS

Objectives. The aim of the research is to study the influence of the microwave electromagnetic field on the thermophysical characteristics of PCM reinforced with carbon fibers as one of the factors indicating a certain restructuring of the material, leading to a change in its operational properties.Method. The use of modifying hardening effects that do not lead to excessive destructuring heating of materials.Result. Based on the analysis of scientific and technical literature and trends in the development of technical transport and energy systems, a steady increase in the cons umption of fibrous polymeric composite materials (PCM) in their structures has been revealed. The prospects of applying the effects of microwave radiation (microwave electromagnetic field) on the formation of the required properties of products from PCM and the feasibility of studying the mechanisms of interaction of microwave radiation with the structure of solidified PCM are shown. Experimental studies of the thermophysical interaction of PCM reinforced with carbon fibers with a microwave electromagnetic field with a frequency of 2450 MHz were performed.Conclusion. The fact of more intensive heating of samples of greater thickness and their greater shielding capacity was established. In the study of the thermophysical parameters of PCM subjected to preliminary processing in the microwave electromagnetic field by the modified Parker method, an increase in certain exposure modes of the thermal and thermal conductivities by 20% was observed, which indicates an increase in adhesive bonds in the interfacial zones and an increase in the structure density. This fact can be used in the development of technologies for modifying products from PCM, designed to work in conditions of elevated temperature gradients, which will reduce the magnitude of thermal stresses.Acknowledgment. The research was supported by RFBR grant No. 17-03-00720 «Methodology of optimising microconstruction of composite materials for complex shape objects with increased dynamic strength, formed layer-by-layer by electrotechnological methods».

Investigation of elastic deformations of cured CFRP structures with embedded cellular metallic elements subjected to a microwave electromagnetic field

Based on the analysis of trends in the development of aviation equipment for various purposes, the expansion of the use in its bearing structures of polymer composite materials, reinforced with carbon fibres with a combined structure containing distributed in the volume of metal honeycomb fillers is shown. This increases the anisotropy of the physical and mechanical properties of such structures of different chemical composition and properties of materials, which makes it difficult to manoeuvre the aircraft due to the different stability of metals and composites to multidirectional dynamic bending and shear loads. It is stated that the problem of increasing the strength characteristics of PCM can be solved by their quasi-structuring in the microwave electromagnetic field, but the influence of this factor on complex structures containing metal regular elements needs further study. Experimental studies of the effect of short-term exposure to microwave electromagnetic field with a frequency of 2450 MHz on the modulus of material elasticity, which is a structure of two plates of carbon fibre with aluminium cellular elements located between them. It was found that compared with the control samples, the samples exposed to microwave electromagnetic field have an increased modulus of elasticity by 31.8%. Limit shear stresses also increase by 29%. Thus, the treatment of formed and cured polymer composite materials with built-in cellular metal structures in the microwave electromagnetic field is possible and allows to perform hardening quasi-structuring of such products and increase their performance parameters.

Ni-Co-Cr/Al2O3/Al Catalysts with a Nanostructured Active Component: Microwave-Assisted Synthesis and Activity in the Reaction of Toluene Steam Dealkylation

It is shown that the reaction of toluene steam dealkylation can be intensified in the presence of microwave radiation-absorbing Ni-Co-Cr/Al2O3/Al catalysts with the nanostructured active component under application of a microwave electromagnetic field to the reaction medium. It is found that the favorable effect of microwave radiation on the rate of reaction and selectivity for the target product benzene is most probably related to the formation of a more developed active surface owing to the formation of Ni and Co chromites as uniformly distributed nanosized clusters with linear sizes of 20–80 nm.

Study of mechanical and protective characteristics of composite materials based on aramid fabrics modified in a microwave electromagnetic field

The studies of the protective characteristics of samples of armor packages, which are compositions of aramid fabric TSVM-J and glue 88, after influenced by the microwave electromagnetic field, have been carried out. A reduction in the number of maximum punctured layers to 7, and an armor effect to 10 mm was stated. In this case, compared with the control sample, a significant change in the mechanical characteristics of the composite armor package was found. Density increased by more than 10%. At the same time, the tensile ductility decreased by (40-47)%, and the elastic deformation with indentation increased almost 5 times. The results obtained after their refinement and substantiation of the physical mechanism can be used as the basis for the development of technologies for enhancing the characteristics of armor protection elements made of composite ballistic materials and structural organoplastics for aircraft.

Study of the microstructure of aramid fabrics for structural and protective organoplastics modified in a microwave electromagnetic field

The microstructure of samples of aramid fabric TSVM-DZh, subjected to the influence of the microwave electromagnetic field of an average power level with a frequency of 2450 MHz, was investigated. A significant change in the conditions of contact of individual filaments at the level of the interfibrillary bond of fibers, expressed in the integration of fibrils into agglomerates, filling gaps between the fibers with an increase in the interaction area and in the convergence of individual fibers, which improves the reliability of intermolecular bonds was established. The obtained results can be used as one of the mechanisms for increasing the strength characteristics of structural organoplastics and protective materials from aramid fabrics after microwave exposure.

Experimental results of increasing the bending strength of construction glass after microwave radiation exposure

The analysis of the scientific and technical literature and trends in the development of transport and energy technology showed that advanced plastic complexes and fiberglass plastics are widely used in promising aviation complexes and ground-based robotic complexes for various purposes. The promising point of application of the effects of microwave radiation (microwave electromagnetic field) on the formation of enhanced strength properties of products made of glass-reinforced plastics, especially in terms of bending stresses and interlayer shear, is shown. Experimental studies of the effect of microwave electromagnetic field with a frequency of 2450 MHz on the microstructure of hardened laminated fiberglass and their flexural strength have been performed. A 60% increase in the flexural strength of the samples was achieved after exposure to microwave radiation of an average power level for 2 minutes compared to the control ones. With shorter and longer time of processing, the increase of strength was less pronounced. The reason of hardening is an increase of the solidity of the structure by increasing the contact points of the matrix and fibers during the formation of the characteristic “star” structures. The fact of embrittlement of samples processed at maximum radiation power with an increase in exposure time was revealed.

Modeling of Passive Intermodulation in Connectors With Coating Material and Iron Content in Base Brass

Ferromagnetic materials in coaxial connectors are one of the main contributors to passive intermodulation (PIM) in radio frequency systems. In this paper, the effects of coating materials and iron content in base brass on PIM performance were theoretically modeled and analyzed, and the results experimentally verified. A finite-element analysis model for a cross section of the inner conductor was developed to evaluate the current density distribution in connectors with different materials, coating thickness, and iron content in the base copper alloy. Simulation calculations were performed to study the nonlinear characteristics induced by ferromagnetic materials in the communication frequency band. The relationship between the PIM products power and the current density distributions was investigated based on the theory of microwave electromagnetic fields and nonlinear mathematical modeling. This model was used to theoretically predict the intermodulation (IM) products power resulting from connectors with various material properties. In addition, a series of experiments based on two-tone testing was conducted to measure IM products of specific connectors. Good agreement was observed between experimental measurements and the predictions of the analytical model, validating the PIM analysis method and results.

Combined Spatially Resolved Optical Emission Imaging and Modeling Studies of Microwave-Activated H2/Ar and H2/Kr Plasmas Operating at Powers and Pressures Relevant for Diamond Chemical Vapor Deposition.

Microwave (MW) activated H2/Ar (and H2/Kr) plasmas operating under powers and pressures relevant to diamond chemical vapor deposition have been investigated experimentally and by 2-D modeling. The experiments return spatially and wavelength resolved optical emission spectra of electronically excited H2 molecules and H and Ar(/Kr) atoms for a range of H2/noble gas mixing ratios. The self-consistent 2-D( r, z) modeling of different H2/Ar gas mixtures includes calculations of the MW electromagnetic fields, the plasma chemistry and electron kinetics, heat and species transfer and gas-surface interactions. Comparison with the trends revealed by the spatially resolved optical emission measurements and their variations with changes in process conditions help guide identification and refinement of the dominant plasma (and plasma emission) generation mechanisms and the more important Ar-H, Ar-H2, and H-H2 coupling reactions. Noble gas addition is shown to encourage radial expansion of the plasma, and thus to improve the uniformity of the H atom concentration and the gas temperature just above the substrate. Noble gas addition in the current experiments is also found to enhance (unwanted) sputtering of the copper base plate of the reactor; the experimentally observed increase in gas phase Cu* emission is shown to correlate with the near substrate ArH+ (and KrH+) ion concentrations returned by the modeling, rather than with the relatively more abundant H3+ (and H3O+) ions.

THE DEPENDENCE OF MALIGNANT CELLS' GROWTH RATE ON THE CHARACTERISTICS OF THE STATIC MAGNETIC FIELD

We identified patterns of K562 cell line of human erythroleukemia growth speed change depending on such magnetic field characteristics as magnetic field strength, direction and time of exposure. We identified presence of growth speed extremum in the function of magnetic field exposure time. Based on the generally accepted assumption that main biochemical reactions of energy carriers’ synthesis in biological objects have spin-spin relationships between chemical elements participating in chemical reactions, they depend on magnetic field and electromagnetic microwave field. Hopefully, clarification of energy carriers’ synthesis mechanism in cancer cells will allow us to evaluate the probability of decrease of its effectiveness in terms of proliferation and probably establish examples of magnetobiological effects practical use for cancer cell growth regulation.

EMF Induced in a p–n Junction under a Strong Microwave Field and Light

The effect of a strong electromagnetic field on currents and electromotive forces in a p–n junction is considered. It is shown that a p–n junction upon exposure to an electromagnetic wave becomes a source of electromotive force (emf) dependent on current. An analytical expression for the emf and internal resistance of such a source is derived. Dependences of the electromotive force and internal resistance on diode currents are obtained from the experimental current–voltage characteristic of a p–n junction placed into a strong microwave (UHF) electromagnetic field.

Experimental study of the influence of high frequency and microwave electromagnetic fields on oil shales

Experimental study of the influence of high frequency and microwave electromagnetic fields on oil shales