Alexander V. Lazukin

One of the key tasks in the framework of creating a prototype plasma rocket thruster based on a quasi-stationary high-current plasma accelerator (QSPA) is the operation of the QSPA in a pulse-periodic mode. The transition from a single-pulse mode, in which the QSPA has been operated until now, to a pulse-periodic mode requires the significant change of a control system. This paper presents the requirements on the control, acquisition and archiving system, which ensures the operation of the QSPA in a pulse-periodic mode. The proposed control system architecture is based on the principles of distributed control and minimal connectivity. Also, the paper describes the testing of a control system key task, namely, the execution a sequence of acquisition and analysis of diagnostic data. Test results demonstrate, that the control system architecture developed using standard hardware is able to ensure the operation of the QSPA in a pulse-periodic mode with a frequency of up to 10 Hz for up to 20 min.

A sinusoidal high-voltage high-frequency (20 kHz) power supply is simulated in the Matlab environment. In the power supply model developed, the principle of constructing the control system feedback signal from the load represented by the plasma jet equivalent circuit is proposed. The power supply main functional units are presented, including a rectifier with a filter, a step-down converter, an inverter, and a step-up transformer. To obtain better simulation quality, the characteristics of the chokes and the step-up transformer were refined on the mockups of these components. The feedback signal pickup points (the charge transferred to the nozzle wall) and the control signal application points (the controller and the step-down converter) are selected. The possibility of influencing the load through the obtained control channel is shown; the response time to the model disturbance was found to be 17 ms. The control system functional diagram demonstrates the possibility of regulating the plasma jet operation mode by using the charge transferred to the nozzle wall as the feedback signal. The control is performed by adjusting the voltage applied to the inverter-transformer-gas discharge system. The proposed model can be applied in constructing devices that use a plasma jet as an actuator, and also in designing high-voltage power supplies. Статья посвящена моделированию в среде MATLAB источника синусоидального высокого напряжения повышенной частоты (20 кГц). В разработанной модели источника питания предложен принцип построения сигнала обратной связи системы управления от нагрузки, представленной схемой замещения плазменной струи. Рассмотрено наполнение основных функциональных блоков источника питания: фильтр-выпрямитель, понижающий преобразователь, инвертор, повышающий трансформатор. Для повышения качества моделирования характеристики дросселей и повышающего трансформатора уточнялись на макетах этих изделий. Выбраны точки снятия сигнала обратной связи (заряд, перенесенный к стенке сопла) и точки приложения сигналов управления (регулятор и понижающий преобразователь). Показана возможность влияния на нагрузку по созданному каналу управления; время отклика на модельное возмущение составило 17 мс. Функциональная схема системы управления демонстрирует возможность регулирования режима работы плазменной струи по перенесенному к стенке сопла заряду. Управление осуществляется путем регулирования напряжения, подводимого к системе инвертор–трансформатор–газовый разряд. Предложенная модель необходима при создании устройств, использующих плазменную струю в качестве исполнительного, и при проектировании высоковольтных источников питания.

Background. Presently, a selection of environmentally friendly technologies for pre-sowing treatment of wheat seeds is conducted in agriculture. Ozone, an allotropic form of oxygen, is highly reactive, acts as an effective insecticide, promotes seed improvement, and reduces soil contamination. The impact of ozone on seeds is one of the promising technologies to improve the quality of seedlings. It is known that the field germination of winter wheat may be less than 50%, depending on the environmental conditions, and therefore the quality of seedlings is very important. Purpose. To evaluate the effect of different ozone concentrations on morphological parameters and synthesis of fatty acids (FA) in winter wheat seedlings. Materials and methods. The object of the study was the seeds of soft winter wheat (variety Irkutskaya). The ozonation was conducted with ozone concentrations of 2, 4, 6 and 8 g/m3 during 15, 30, 45 and 60 min. The germination of treated and control seeds was carried out for three days in the dark in a thermostat (24±1°C). On the third day, the morphometric characteristics were measured. The extraction of lipids from shoots and roots was carried out according to the method of Bligh, Dyer [14]. The methyl esters of lipid fatty acids were analyzed by chromato-mass spectrometry. Statistical data processing was conducted with the use of R programming language and SigmaPlot v. 12.5. Results. Ozone in concentrations of 2, 4, 6 g/m3 has a stimulating effect on seedling germination, the length of the shoots and roots increases. At ozone concentration of 8 g/m3, the length of the shoots and roots decreases. There is a general trend in the content of fatty acids, in the shoots of seedlings there is some decrease in lipid unsaturation, and in the roots - some increase in lipid unsaturation. Conclusion. Ozone in concentrations up to 8 g/m3 is suitable for pre-sowing seed treatment and improves seedling performance. Обоснование. В настоящее время в сельском хозяйстве идет подборка безопасных для окружающей среды технологий предпосевной обработки семян пшеницы. Озон, аллотропная форма кислорода, обладает высокой реакционной способностью, выступает как эффективный инсектицид, способствует оздоровлению семян, снижению зараженности почвы. Воздействие озоном на семена входит в группу перспективных технологий по повышению качества всходов. Известно, что полевая всхожесть озимой пшеницы в зависимости от окружающих условий может быть менее 50% и поэтому важно качество всходов. Цель. Оценить влияние разных концентраций озона на морфологические показатели и синтез жирных кислот (ЖК) в проростках пшеницы озимой. Материалы и методы. Объектом исследования являлись семена мягкой озимой пшеницы сорта "Иркутская". Озонирование проводилось при концентрациях озона 2, 4, 6 и 8 г/м3 и экспозициях 15, 30, 45 и 60 мин на каждой из концентрации. Проращивание обработанных и контрольных семян проводили в течение трех суток в темноте в термостате (24±1°С). На третьи сутки измеряли морфометрические характеристики. Экстракцию липидов из побегов и корней проводили по методу Bligh, Dyer [14]. Метиловые эфиры жирных кислот липидов анализировали методом хромато-масс-спектрометрии. Статистическая обработка данных проведена с помощью языка программирования R, программы SigmaPlot v. 12.5. Результаты. Концентрации озона 2, 4, 6 г/м3 оказывают стимулирующее действие – увеличивается длина побега и корня. При концентрации озона 8 г/м3 длина побега и корня уменьшается. В содержании ЖК наблюдается общая тенденция, в побегах проростков идет снижение, а в корнях – увеличение ненасыщенности липидов. Заключение. Концентрации озона до 8 г/м3 подходят для предпосевной обработки семян и улучшают показатели всходов.

Cold argon plasma (CAP) and metal oxide nanoparticles are well known antimicrobial agents. In the current study, on an example of Escherichia coli, a series of analyses was performed to assess the antibacterial action of the combination of these agents and to evaluate the possibility of using cerium oxide and cerium fluoride nanoparticles for a combined treatment of bacterial diseases. The joint effect of the combination of cold argon plasma and several metal oxide and fluoride nanoparticles (CeO₂, CeF₃, WO₃) was investigated on a model of E. coli colony growth on agar plates. The mutagenic effect of different CAP and nanoparticle combinations on bacterial DNA was investigated, by means of a blue–white colony assay and RAPD-PCR. The effect on cell wall damage, using atomic force microscopy, was also studied. The results obtained demonstrate that the combination of CAP and redox-active metal oxide nanoparticles (RAMON) effectively inhibits bacterial growth, providing a synergistic antimicrobial effect exceeding that of any of the agents alone. The combination of CAP and CeF₃ was shown to be the most effective mutagen against plasmid DNA, and the combination of CAP and WO₃ was the most effective against bacterial genomic DNA. The analysis of direct cell wall damage by atomic force microscopy showed the combination of CAP and CeF₃ to be the most effective antimicrobial agent. The combination of CAP and redox-active metal oxide or metal fluoride nanoparticles has a strong synergistic antimicrobial effect on bacterial growth, resulting in plasmid and genomic DNA damage and cell wall damage. For the first time, a strong antimicrobial and DNA-damaging effect of CeF₃ nanoparticles has been demonstrated.

The erosion of nanostructured tungsten and titanium by high-heat plasma flux, laser, and arcing is investigated. To fabricate nanostructural fuzz layers and hierarchical granularity on the surfaces, samples were exposed to helium plasma in the steady-state plasma device PLM-M, which is a linear plasma trap of an eight-pole multicusp magnetic field with parameters similar to the scrape-off layer and divertor plasma in a tokamak. Arcing ignited with a Nd:YAG laser pulse on the target fuzzy surface in the helium plasma resulted in the melting of fibers and the creation of craters of several microns in depth and several tens of microns in diameter.

This work compares the presowing treatment of winter wheat seeds with a low-temperature plasma, a constant high-voltage electric field, a plant protection disinfectant, and cold hardening on the resistance of seedlings to freezing and their morphophysiological characteristics at the initial stage of germination. Various treatment combinations were considered, including the effect of the disinfectant jointly with low-temperature plasma treatment. The greatest stimulating effect from the point of view of seedlings’ morphophysiological characteristics was achieved when seeds were cold-hardened. The action of low-temperature plasma is noticeable up to the third day of germination. The treatment with the low-temperature plasma of seeds pretreated and not-pretreated with the disinfectant had a similar effect on the morphophysiological characteristics of seedlings. The plasma treatment and the electric field were combined with each other, i.e., the plasma treatment effects were added to the electric field effects. Resistance to low temperatures was increased with the hardening of seeds treated with the electric field and the disinfectant. Resistance to low temperatures was reduced when treated with the electric field and/or low-temperature plasma after being treated with the disinfectant.

This study investigated the effect of ozone and constant electric field on the morphological and physiological characteristics of tomato and wheat seedlings with the purpose of creating an effective and environmentally friendly technology for increasing the growth potential of crop seeds. Seeds of cv. Ventura tomato (Solanum lycopersicum L.) and cv. Irkutskaya soft winter wheat (Triticum aestivum L.) were exposed to ozone concentrations of 1, 3, and 5 g/m3 and electric field strengths of 1.6 and 2 kV/cm. The exposure time was 15 and 30 min. Both ozone and constant electric field were found to expand the spread of data on the shoot and root length, as well as alter the energy of seed germination. Depending on ozone concentrations and electric field strengths, the effect of seed treatment was established to be both positive and negative. The most optimal mode for ozonization of tomato seeds was achieved at an ozone concentration of 5 g/m3 for 15 minutes. The optimal mode for treating tomato seeds by electric field was achieved at an electric field strength of 1.6 kV/cm for 15 min. Wheat was determined to response to treatment not as intensively as tomato. When treating wheat seeds, ozonization is a more preferable method, since it stimulates germination even at an ozone concentration of 1 g/m3 for 15 minutes. However, our experimental results showed that even small changes in the mode of exposure both to ozonization and electric field can result in seed damage, thereby inhibiting the development of plants and decreasing the seed germination energy.

The results of an experimental study of the dependence of the energy of a surface barrier discharge on the value of the supply sinusoidal voltage with a frequency of 4 and 20 kHz in the electrode system of parallel stripes with a distance between them of 5 and 30 mm are presented. At a distance of 5 mm between the strips, there is a self-limited surface discharge in the electrode system. Self-limiting of the discharge leads to the fact that with an increase in the applied voltage, the energy invested in the electrode system increases more slowly than in the case when the discharge exists without restrictions. The energy of a self-limited discharge is 15-40% lower than the energy of a discharge that exists without restriction. Keywords: surface discharge, energy, volt-coulomb characteristic, self-limited discharge.

In this work, the experimental results of surface barrier discharge plasma products affection to winter rye seed germination at the initial stage of growth and seedling tolerance to low temperatures are shown. The treatment was carried out for 10, 60, and 180 s in the plane-parallel electrode system with sinusoidal voltage of 2.7 kV with frequency 4.4 kHz applied to the strip electrodes at a distance of 5 mm from each other. It is shown that the treatment has no effect on seed germinating ability. In 180 s exposure treatment mode the stimulation of 3-day seedling shoot and root system length occurs. The freeze tolerance response of two-stage cold hardened seedlings grown from treated seeds shows that both the exposure of seed and the freezing temperature affect on the formation of positive response.

The results of an experimental study of the dependence of the energy of a surface barrier discharge on the value of the supply sinusoidal voltage with a frequency of 4 and 20 kHz in the electrode system of parallel stripes with a distance between them of 5 and 30 mm are presented. At a distance of 5 mm between the strips, there is a self-limited surface discharge in the electrode system. Self-limiting of the discharge leads to the fact that with an increase in the applied voltage, the energy invested in the electrode system increases more slowly than in the case when the discharge exists without restrictions. The energy of a self-limited discharge is 15-40% lower than the energy of a discharge that exists without restriction