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Акишев, Юрий Семенович

Организационные подразделения

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Институт лазерных и плазменных технологий

Стратегическая цель Института ЛаПлаз – стать ведущей научной школой и ядром развития инноваций по лазерным, плазменным, радиационным и ускорительным технологиям, с уникальными образовательными программами, востребованными на российском и мировом рынке образовательных услуг.

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Акишев

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Юрий Семенович

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Теперь показываю 1 - 10 из 28

Только метаданные
Effect of High-Voltage Electrode Potential Bias on the Breakdown Induced by Ionization Wave in Discharge Tube
(2020) Meshchanov, A. V.; Ionikh, Y. Z.; Akishev, Y. S.; Акишев, Юрий Семенович
© 2020, Pleiades Publishing, Ltd.Abstract—: An experimental study has been done of the bias effect of the active (high-voltage) electrode potential on the breakdown characteristics in a discharge tube 15 mm in diameter, filled with neon, argon, or their mixture (3 : 1) at a pressure of ~1 Torr. The bias of the potential is carried out by parallel connection to the electrode with an additional constant voltage or additional pulses with an amplitude less than the voltage for maintaining self-sustained discharge. In this case, a change in the breakdown voltage, the velocity of the pre-breakdown ionization wave, and the brightness of radiation from its front is observed. In particular, the breakdown voltage can increase up to 1.5–2 times, and this state of the discharge gap can be maintained for tens of minutes. The observed effects are assumed to be caused by the appearance of a charge on the tube wall and a change in its potential near the electrode, which affect the characteristics of the primary breakdown between the electrode and the wall and, in turn, the processes of discharge ignition. The mechanisms of appearance of the surface charge on the wall when feeding a bias voltage to electrode are investigated.
Только метаданные
Electrical analysis and ultra-fast sequential imaging of surface barrier discharge with streamer-leader sequence generated with 100 kHz frequency at the water interface
(2019) Synek, P.; Petryakov, A.; Trushkin, N.; Vorac, J.; Akishev, Y.; Акишев, Юрий Семенович
A time resolved study of the electrical parameters and ultra-fast 2D imaging of the surface barrier discharge emerging from liquid electrodes in atmospheric pressure argon is reported. Analysing the electrical measurements and the charge-voltage (Q-V) plots, a resistive component of the electrical system impedance is revealed and described by the logical progression of the method to current-voltage (I-V) plots. The necessity to include a resistive component in the simplest equivalent circuit is demonstrated. Net discharge current, charge or effective gap voltage are linked to the light emission. A special nanosecond-gated camera enabling multiple expositions within a few hundreds of nanoseconds is applied and reveals the spatiotemporal development of the discharge luminosity. Propagation of the streamer-leader stepping sequence on the dielectric surface is observed and the mean velocities and axial light-emission development is quantified. A light emission of an excited gas prior to and after the discharge's main current peak is detected revealing an increased activity between the subsequent discharges. This is caused by the high pre-ionisation of the gas volume and the intensive charging of the surface. The generation of subsequent streamers emerging from/between the surface charge domains is evidenced.
Только метаданные
The "memory" effect of microdischarges of a barrier discharge in airflow Эффект "памяти" микроразрядов барьерного разряда в потоке воздуха
(2019) Usenov, E. A.; Petryakov, A. V.; Ramazanov, T. S.; Gabdullin, M. T.; Akishev, Yu. S.; Акишев, Юрий Семенович
© 2019 Federal Informational-Analytical Center of the Defense Industry. All rights reserved.The experimental results on the dynamics of microdischarges of the volume barrier discharge in rail electrode geometry along which the atmospheric pressure airflow was blown are presented. The aim of this work is the clarification of a role of volume plasma and surface charges in the “memory” effect of microdischarges. On the basis of the analysis of the microdischarges images taken with the use of the high-speed camera, it is established that transportation of plasma channels by a gas flow defines the localization of emergence of every microdischarge in each subsequent half-cycle of the sinusoidal voltage. An important role plays the turbulence of airflow and existence in it of whirlwinds which determine both the speed of plasma channels transportation and the possibility for the appearance of microdischarges in a concrete half-cycle. Results show a possibility to control the parameters of a barrier discharge by gas dynamics.
Только метаданные
About the possible source of seed electrons initiating the very first breakdown in a DBD operating with the air at atmospheric pressure
(2021) Karalnik, V.; Medvedev, M.; Petryakov, A.; Shao, T.; Akishev, Y.; Акишев, Юрий Семенович
© 2021 IOP Publishing Ltd.The conditions of the very first breakdown happening in a periodical dielectric barrier discharge (DBD) are not the same as those in the discharge established regime. The main intriguing problem in the very first breakdown is the source of the initial seed electrons. In this work, the role of atmospheric small negative ions in the appearance of seed electrons is investigated. The very first breakdown was studied by using a pin-to-plane barrier corona and plane-to-plane DBD operated with ambient air. These discharges were driven by fast- and slow-growing applied voltage. The experimental data related to the very first breakdown are presented. A short summary sounds as follows. In the case of a barrier corona initiated by a fast-growing voltage, seed electrons can appear due to their detachment from background negative ions in the bulk. Under a slow-increasing voltage, background ions have the time to be fully adsorbed on the cathode and the anode long before breakdown occurs. In such a case, seed electrons can appear from negative ions desorbed from the cathode. This desorption is induced by a strong electric field in the gap. The latter mechanism can work in a plane-to-plane DBD driven by both fast- and slow-growing applied voltage. Based on numerical calculations, a qualitative explanation of the obtained results is given. The influence of UV irradiation on the very first breakdown was also studied.
Только метаданные
On the Development of Ionization Waves Preceding Breakdown in a Long Capillary Tube Filled with Helium at Low Pressure
(2021) Karal'nik, V. B.; Petryakov, A. V.; Ionikh, Y. Z.; Akishev, Y. S.; Акишев, Юрий Семенович
© 2021, Pleiades Publishing, Ltd.Abstract: Experiments that revealed the main trends in the development of complete breakdown in a long capillary tube for different electrode configurations are reported. It is demonstrated that, in the presence of an additional external electrode around the tube, a fast stage completing the breakdown is preceded by a slow stage caused by development of a weak-current surface barrier discharge inside the tube. This discharge is realized due to propagation of forward (from the high-voltage electrode) and backward (from the grounded electrode) surface ionization waves. The presence of preliminarily, locally deposited charge of the sign opposite to polarity of the voltage pulse leads to acceleration of propagation of ionization waves in the tube. In the absence of the external electrode, the breakdown occurs much faster but is characterized by a large scatter in the delay time (up to complete lack of breakdown) relative to the applied voltage pulse. Unstable operation of the gas-discharge device determined by development of breakdown represents a much more serious problem in many applications compared to the situation in which it turns on slowly but stably. Therefore, the results demonstrating the possibility of controlling the breakdown are of great scientific and practical value.
Только метаданные
Radial current distribution along the ionization wave propagating in a long dielectric capillary tube filled with a low-pressure helium
(2021) Karalnik, V. B.; Petryakov, A. V.; Akishev, Y. S.; Акишев, Юрий Семенович
© 2021 Institute of Physics Publishing. All rights reserved.The experimental results on the study of the ionization wave propagating along a long capillary tube are presented. The ionization wave was initiated by high-voltage pulse of positive or negative polarity. The propagation of this surface ionization wave precedes and influences the establishment of complete electric breakdown within the tube. The spreading of this wave is accompanied by the surface charge deposition. The usage of the fine-sectioned outer electrode allows one to find out the general features of the ionization waves.
Только метаданные
Features of a negative ionization wave development preceding the full breakdown in a long capillary tube wrapped with a continuous or fine-sectioned grounded electrode
(2021) Karalnik, V. B.; Petryakov, A. V.; Akishev, Yu. S.; Акишев, Юрий Семенович
© 2021 Institute of Physics Publishing. All rights reserved.The experimental results on the study of negative ionization wave propagating along a long capillary tube are presented. The ionization wave was initiated by high-voltage pulse of negative polarity. The propagation of this surface ionization wave precedes and influences the establishment of complete electric breakdown within the tube. The spreading of this wave is accompanied by the surface charge deposition. The usage of the fine-sectioned outer electrode allows one to find out the general features of a negative ionization wave. The main of them is the tight correlation between local currents determining the formation of local surface charge and visual discharge images taken by the fast camera characterizing the pace of the ionization wave propagation.
Только метаданные
Use of non-thermal plasma for decontamination of titanium implants
(2022) Sysolyatina, E.; Petryakov, A.; Abdulkadieva, M.; Vasilieva, E.; Chernukha, M.; Avetisyan, L.; Alekseeva, T.; Barsuk, V.; Ermolaeva, S.; Titov, N.; Akishev, Y.; Акишев, Юрий Семенович
Non-thermal plasma (NTP) has a non-specific bactericidal effect as a result of the synergistic activity of biologically active components contained in the plasma torch. As part of this work, we investigated the potential of using NTP for the antibacterial treatment of titanium implants. Applying samples made of the VT6 titanium alloy used to create implants and a strain of antibiotic-resistant staphylococcus MRSA, we showed that 1) plasma pretreatment of the sample surface led to the formation of a film containing titanium oxides which have a weak bactericidal effect reducing the colonization of the surface with staphylococcus; 2) direct plasma treatment of a polished titanium disk for 120 seconds reduced the contamination of S. aureus by 563 times; 3) the relief of the titanium surface itself plays an important role in the effectiveness of decontamination: the bacteria on the rough surface were less susceptible to the effects of NTP than the bacteria on the polished surface. In total, the data obtained indicate the need to continue research aimed at increasing the effectiveness of the bactericidal activity of NTP against bacteria on the surface of titanium implants. © Published under licence by IOP Publishing Ltd.
Только метаданные
On constriction and striation of a diffuse DBD in large gap filled with moderate pressure helium diluted by the air and easily ionized impurity
(2022) Akishev, Y.; Alekseeva, T.; Karalnik, V.; Petryakov, A.; Акишев, Юрий Семенович
The experimental results on studying the plane-to-plane dielectric barrier discharge (DBD) excited in a very large volume (120 × 120 × 120 mm3) are presented. The DBD was powered by sinusoidal voltage with a frequency of 100 kHz. The plasma-forming gas is helium, which is slightly diluted by the air and trace impurity of an easily ionized gas. The total pressure of the working gas was varied within of 20-100 Torr. A moderate gas pressure allowed one the creation of non-typical DBD with a very long plasma column of 12 cm in length. Such a long gap DBD exhibits new features in its behavior compared to the well-known DBD in short gaps of several millimeters in length. Immediately after the discharge ignition, a long and uniform diffuse plasma column occurs that occupies the entire space of the inter-electrode bulk. However, this transversally homogeneous plasma mode is unstable. The ionization-thermal instability develops in the plasma owing to gas heating by the discharge. Therefore, the transversally uniform plasma breaks into several separate narrow current channels that move chaotically relative to each other. After a while, they eventually integrate into a single constricted plasma column located in the center part of the discharge volume. At the very beginning of its formation, the constricted plasma column is longitudinally uniform. But soon, it becomes streated. The strata are almost standing and their shape differs from that in a DC glow discharge at low pressure in a sealed tube. The revealed features in the slow spatial-temporal behavior of the long gap DBD are discussed with the involvement of mathematical analysis describing the small plasma disturbance development in the linear approximation. © 2022 IOP Publishing Ltd.
Только метаданные
On the slow ionization waves forming the breakdown in a long capillary tube with helium at low pressure
(2022) Akishev, Y.; Alekseeva, T.; Karalnik, V.; Petryakov, A.; Акишев, Юрий Семенович
The results of studies of an electrical breakdown leading to the glow discharge ignition in a long capillary quartz tube are presented. Under such conditions, the breakdown completion is preceded by the development of direct, backward, and counter slow ionization waves (IWs) traveling in the tube. The initiation of the waves was created in helium at low pressure (P = 10 Torr) by the high-voltage pulses of positive and negative polarity with amplitude of several kilovolts. In the beginning, the regime without the breakdown completion in the tube was studied. In this regime, the propagation of only direct positive and direct negative IWs happens. The research on dynamics of the direct, backward, and counter positive and negative waves followed by a complete breakdown was done as well. The influence of the pre-existing plasma on the IWs propagation was also studied. The plasma was created in advance by low-current glow discharge being formed in the tube. The instant images of IWs were correlated with the electrical currents formed by the waves, that is, with the displacement current through the dielectric wall and the conductive current through the plasma column. In the experiments, the fine-sectioned electrode wrapped around the lateral tube surface was used. The usage of such electrode allowed one to study the dynamics of the surface charge deposition and deletion happening during the direct and backward wave propagation, respectively. Finally, a strong difference in the spatial structure and velocity of positive and negative direct waves traveling through non-ionized gas was revealed. Contrary, both the positive and negative backward waves traveling through the plasma formed by previous direct waves have the parameters close to each other.