Ultra High-Frequency Electric Installation with a Hybrid-Type Working Chamber

Ultra-high frequency (UHF) electric installations, using the energy of UHF electromagnetic oscillations, can perform thermal UHF modification of dielectric materials and products. As a result, its properties and parameters change in an object processed in a UHF electromagnetic field faster and more uniformly than when the heat is transferred to a heated dielectric by thermal conductivity, convection, thermal radiation. The exact change in the properties and parameters of polymers of living and inanimate nature, uniform in volume and significantly in a shorter time spent in a UHF electromagnetic field, can be obtained in UHF electrical installations, and practically without heating the object as a result of the so-called non-thermal UHF modification. The paper proposes the design and design of a UHF electric installation with a hybrid-type working chamber. Such a working chamber makes it possible to simultaneously carry out non-thermal UHF modification of a polymer and thermal UHF modification of a dielectric in one installation. A UHF electric installation with a hybrid-type working chamber is cheaper. It takes up less space than two separate installations producing the same products with the same productivity.

Study of the effects of ultra-low intensity electromagnetic fields on biological objects

The object of research is the efficiency of exposure to electromagnetic field (EMF) of ultra-low intensity on biological objects, which is formed by a generator of broadband radiation. The principle of action of the generator is based on formation of electromagnetic radiation induced by periodic pulsed gas discharge in coaxial system of electrodes, which is loaded on a dielectric rod antenna. The method of selection of signals and corresponding equipment, which energy characteristics of radiation correspond to the criterion of non-thermal influence on bioobjects, is developed for obtaining a comparative assessment of influence bioefficiency. The proposed new method for processing experimental data using statistical calculations that meet the requirements for the processing and interpretation of the results. The seeds of wheat and interaction of millimeter range electromagnetic oscillations with bone marrow cells of rats were used as biological objects for investigating the effect of millimeter range electromagnetic oscillations. A biosensory effect was obtained when exposed to broadband radiation of ultra-low intensity, compared to the control sample. A change in the properties of the seeds, in particular, heat resistance, is observed. According to the experimental data, seeds turn out to be less susceptible to heat as a result of their pretreatment with EMF. The biological response is observed to depend on the frequency and time of irradiation. Also, the dependence of the decrease in the number of dead cells on the time of EMF irradiation was experimentally proved. The equation of dependence of selective average proportion of dead cells in rat bone marrow on irradiation time was calculated. Biosensory effect of exposure to broadband ultra-low intensity EMF of the developed emitter was revealed. It was established and statistically proved that the minimum time with the maximum positive effect of exposure to electromagnetic radiation of millimeter range on bone marrow cells of rats is 30 minutes, compared with an unirradiated sample. The results make it possible to evaluate the positive effect of electromagnetic oscillations on biological objects and propose the results of studies for practical use in the development of medical systems.

Investigation of the disinfecting properties of low-frequency electromagnetic oscillations

The drawbacks of the existing methods of disinfection of grain and seeds are shown, a conclusion is made about the absence of a highly effective “green” method, which may be based on low frequency electromagnetic oscillations (up to 1 kHz), which have an inhibitory me chanism. The possibility of deep disinfection and an increase in laboratory germination of seed satcertain low frequencies has been investigated; thanks to their directional (resonant) action, energy savings and other advantages are achieved.

Numerical Investigations of Electromagnetic Oscillations and Turbulences in Hall Thrusters Using Two Fluid Approach

The first part of the contributed chapter discuss the overview of electric propulsion technology and its requirement in different space missions. The technical terms specific impulse and thrust are explained with their relation to exhaust velocity. The shortcoming of the Hall thrusters and its erosion problems of the channel walls are also conveyed. The second part of the chapter discuss the various waves and electromagnetic instabilities propagating in a Hall thruster magnetized plasma. The dispersion relation for the azimuthal growing waves is derived analytically with the help of magnetohydrodynamics theory. It is depicted that the growth rate of the instability increases with magnetic field, electron drift velocity and collisional frequency, whereas it is decreases with the initial drift of the ions.

DISSIPATIVE INSTABILITIES AND SUPERRADIATION REGIMES (CLASSIC MODELS)

The generation of an electromagnetic field by oscillators in an open resonator is discussed in a one-dimensional approximation. In this case, the development of the so-called dissipative instability  the dissipative generation regime. Such an instability with the generation of electromagnetic oscillations arises when the decrement of oscillations in an open resonator in the absence of oscillators turns out to be greater than the increment of the resulting instability of the system of oscillators placed in this resonator. It is assumed that the oscillators do not interact with each other, and only the resonator field affects their behavior. If the resonator field is absent or small, the superradiance regime is possible, when the radiation of each oscillator is essential and the field in the system is the sum of all the eigenfields of the oscillators. In the dissipative regime of instability generation, the system of oscillators is synchronized by the induced resonator field. The synchronization of the oscillators in the superradiance mode owes its existence to the integral field of the entire system of oscillators. With a weak nonlinearity of the oscillators, a small initiating external field is required to excite the generation regime. It is noteworthy that the maximum value of the superradiance field is approximately two times less than the maximum field that the same particles could generate if they were at the same point. In all cases, for a given open resonator, the superradiance field turned out to be somewhat larger than the resonator field. Nevertheless, for the same resonator, the increments and attainable field amplitudes in both cases are of the same order of magnitude.

RESONANT ELECTROMAGNETIC PROCESSES AT UNSTABLE OPERATION OF SLIDING CURRENT COLLECTOR UNITS OF TURBOGENERATOR

The article is devoted to study of the resonance electromagnetic oscillations arising during unstable operation of the sliding current collection unit of turbo-generators. Mathematical modeling of these processes is carried out. It has been established that it is these processes that are the main cause of increased sparking and “ring fire” or “breakdown of commutation” on contact rings.

Simulation of the Propagation of Electromagnetic Oscillations by the Method of the Modified Equation of the Telegraph Line

The article considers the physical processes associated with the propagation of electromagnetic oscillations in a long line, the size of which is the same or slightly greater than the length of the electromagnetic wave (not more than ten times). As a research method, the differential-symbolic method is used, which is applied to the modified equation of the telegraph line. The boundary conditions for the two-point problem as well as additional parameters that are coefficients for the first derivatives in terms of coordinate and time in comparison with the classical equation of the telegraph line are considered as parameters for controlling the process of propagation of electromagnetic oscillations. Based on the differential-symbolic method, the boundary conditions of the two-point problem are found, under which the most characteristic oscillatory processes are realized in a long line. Based on the research, it is possible to draw conclusions about the effectiveness of analytical methods for the analysis of specific technical objects and control of the processes that take place in them.

Demonstration of Damped Electrical Oscillations

Introducing mechanical oscillations in schools is a fairly simple and easy experimental feasible task. To demonstrate electromagnetic oscillations, we have difficulty in understanding by students. The explanation of electromagnetic circuits is more abstract. We offered an experiment where we make electromagnetic oscillations obvious and understandable to students. In our experiment we used the software and interface of the AMSTEL Institute (AMSTEL Institute – Amsterdam Mathematics, Science and Technology Education Laboratory) as well as elements from the sets of experimental tasks from the Physics Olympiads organized by the Sofia branch of physicists.

Nondestructive method of measurement of laminated plates dielectric parameters

The methods for measuring the parameters of dielectric materials of foil plates have been considered. It has been shown that for “non-destructive measurements” (i.e., without removing the metal foil from the dielectric plate), a method based on the excitation of electromagnetic oscillations in a rectangular plate considered as a resonator can be used. Based on the results of measurements of their resonant frequencies and Q-factors, the relative permittivity and the tangent of the dielectric loss angle of the material can be determined. The calculated relations obtained by the authors of the article in one of the early works using the electrodynamic model of a resonator with “magnetic walls” at the ends have been presented. The Q-factor of the resonator has been calculated by the perturbation method, taking into account the losses in the plate dielectric and metallization layers. The results of measurements for four samples from different dielectrics in the frequency range 200...1000 MHz have been presented. The experimental method has been described, in particular, the method of identifying the type of oscillation, the procedure for processing the measurement results. Due to the high sensitivity of the vector analyzer, measurements have been made with a possible small connection of the resonator (metallized plate) with the measuring circuit. This made it possible to minimize the influence of the coupling elements on the measured Qfactor of the oscillations and to consider this Q-factor close to its own. The presented results are in good agreement with the reference data for the materials. The conducted studies have shown the possibility of using a resonator model with “magnetic walls” at the ends for the analysis of electromagnetic oscillations in a foil dielectric plate and, accordingly, using the relations obtained in this case to determine the parameters of the dielectric plate. The conditions for using this model are the small thickness of the plate in comparison with its transverse dimensions and relatively low operating frequencies. The method, which is based on the calculated ratios of the electrodynamic model of the resonator with “magnetic” walls at the ends, provides a sufficiently high accuracy of determining the relative permittivity of the plate material, which led to the use of it (the method) in practice to control the parameters of foil dielectric plates intended for the manufacture of microwave and UHF-band microcircuits. The studies, the results of which have been presented in this paper, allow us to conclude that this method can also be recommended for determining the tangent of the dielectric loss angle of the plate material.