Photosensitive memristor structures based on graphene oxide reduced under hydrothermal conditions are studied. The wavelength of light absorption in such structures was controlled by carbon nanoparticles deposited on the surface of a graphene oxide film. The obtained structures exhibited photomemristive states that were controlled by light of different wavelengths and bias voltages.

The results of studying SiO2 films implanted with 64Zn+ ions with a dose of 5 × 1016 cm–2 at energies of 20 and 120 keV and isochronously oxidized for 1 h at temperatures from 400 to 800°C with a step of 100°C are presented. The profiles of Zn and its oxide are studied using Rutherford backscattering and time-of-flight secondary-ion mass spectrometry. The chemical state of zinc and the phase composition of the film are determined by Auger electron spectroscopy and Raman scattering. It is found that after implantation, the zinc distribution has two maxima at depths of 20 and 85 nm, and after annealing at 700°C there is a broadened maximum at a depth of 45 nm. After implantation, a mixture of Zn and ZnO phases is formed in the sample. After annealing at 700°C, only the ZnO phase is formed in the sample, the distribution profile of which has a broadened peak at 45 nm.

The results of studying SiO2 films implanted with 64Zn ions with a dose of 5 × 1016 cm–2 at energies of 20 and 120 keV and isochronously oxidized for 1 h at temperatures from 400 to 800°C with a step of 100°C are presented. The profiles of Zn and its oxide were studied using Rutherford backscattering and time-of-flight secondary ion mass spectrometry. The chemical state of zinc and the phase composition of the film were determined by Auger electron spectroscopy and Raman scattering. It was found that after implantation, the zinc distribution had two maxima at depths of 20 and 85 nm, and after annealing at 700°C there was a broadened maximum at a depth of 45 nm. After implantation, a mixture of Zn and ZnO phases was formed in the sample. After annealing at 700°C, only the ZnO phase was formed in the sample, the distribution profile of which had a broadened peak at 45 nm.

The results of the synthesis and study of Zn-containing clusters at the interface of a Si3N4/Si film implanted with 64Zn+ ions with a dose of 5 × 1016 cm–2 and an energy of 40 keV are presented. A Si3N4 film is preliminarily deposited onto a silicon substrate using the CVD-method. Then, the implanted samples of 10 × 10 mm are annealed in an oxidizing atmosphere (in air) with a step of 100°С for 1 h at each step in the temperature range from 400 to 800°С. The Rutherford backscattering method is used to study the profiles of zinc during annealing. The structure and composition of the film are studied using scanning electron microscopy in combination with energy-dispersive spectroscopy, as well as photoluminescence. After implantation, individual clusters of metallic zinc with a size of about 100 nm or less are recorded near the surface of the Si3N4 film. It is established that, during annealing, Zn clusters grow in the sample and the phase of metallic Zn gradually transforms into phases of its oxide ZnO and then, presumably, silicide Zn2SiO4. After annealing at a temperature of 700°С, which is the most optimal for obtaining the ZnO phase, zinc-oxide clusters with a size of about 100 nm are formed in the Si3N4 film. A peak appears in the photoluminescence spectrum at a wavelength of 370 nm due to exciton luminescence in zinc oxide. After annealing at 800°C, the ZnO phase degrades and, presumably, the zinc-silicide phase Zn2SiO4 is formed.

This work is devoted to the problem of stable operation of a longitudinal–transverse discharge in a supersonic flow and its parameters. A longitudinal–transverse discharge in an air flow with parameters M = 2, V ~ 500 m/s, T g = 170 K, P st = 22 kPa is considered. High-speed imaging and data acquisition were used to obtain data on the variation of the discharge length, current, and voltage over time. The main purpose of the work was to investigate the dynamics of DC discharge and to describe relations between its geometrical and electrical parameters. Experiments were aimed at obtaining detailed data on the influence of interelectrode distance and discharge current on discharge length and, consequently, on voltage and power release, as well as to determine typical breakdown frequencies depending of discharge parameters. The electrode fall voltage was determined.

Исследованы свойства электрического разряда в сверхзвуковом потоке воздуха и проблема определения температуры контрагированного плазменного канала с радиальным распределением температуры. Рассмотрен прямой разряд длиной 30 мм вдали от стенок канала в ядре сверхзвукового потока с параметрами: число Маха M = 2, скорость потока V ~ 500 м/с, температура торможения T 0 = 300 K, статическое давление газа P st = 22 кПа. Осесимметричная геометрия экспериментов в конфигурации с двумя соосными электродами, расположенными параллельно потоку, была выбрана во избежание появления части канала тока, перпендикулярной потоку, и соответствующих пульсаций разряда. Получена вольтамперная характеристика разряда, и с помощью эмиссионной спектроскопии были установлены зависимости температуры электроразрядной плазмы от электрических параметров разряда. Также с помощью метода теневой визуализации и высокоскоростной съемки была получена оценка толщины теплового конуса, размера разрядного канала и их зависимость от тока разряда.

Представлены результаты численного моделирования разряда постоянного тока в высокоскоростном воздушном потоке с использованием газодинамического кода Plasmaero. Моделирование плазмы разряда было выполнено с использованием одножидкостного МГД-приближения и детальной схемы плазмохимических реакций. В расчетах была получена динамика разряда постоянного тока (в том числе, возникновение перепробоя), которая качественно соответствует экспериментальным данным. Была получена и проанализирована концентрация атомарного кислорода в разных частях разряда. В нульмерном расчете получена оценка влияния наработанного атомарного кислорода на горение этилен-воздушной смеси. Было показано, что наработка атомарного кислорода в разряде постоянного тока может значительно уменьшить время индукции, что важно для стимулирования горения в высокоскоростном потоке.

This paper presents the results of studying the composition, structure, and properties of amorphous SiO x film obtained by electron beam evaporation. This film was implanted by Zn ions with energy of 40 keV and a dose of 3×10 16 /cm 2 . Then, annealing was carried out in air at temperatures from 400 to 800°C with a step of 100°C for 1 hour at each stage. It has been found that, after implantation, metal Zn nanoclusters with a size of about 10 nm are formed on the surface and in the near-surface layer of silicon oxide. During annealing, the implanted layer becomes clear, since metallic Zn gradually oxidizes to transparent phases of its oxide ZnO and silicide Zn 2 SiO 4 . After annealing at 700°C, ZnO nanoclusters and surface craters were revealed on the surface and in the subsurface layer of the SiO 2 film.

This paper presents the results of testing and optimization of a plasma-assisted combustion scheme based on a pylon for fuel injection equipped with a plasma actuator. Electrodes were installed behind the stern of the pylon for the creation of Q-DC discharge with voltage U = 200–2500 V and current I = 3–7.5 A. The experiments were performed in the PWT-50 supersonic wind tunnel of the JIHT RAS under the following conditions: Mach number M = 2, static pressure ~200 Torr, stagnation temperature T0 = 300 K. Gaseous fuel ethylene was used and the fuel mass flow rate was 0.5–4 g/s. The pylon had a streamlined shape that prevented the formation of a stagnant zone; plasma-assisted combustion was performed under more difficult conditions compared to plasma-assisted combustion on a flat wall, where separated flows near the wall are easily formed by discharge. In this work, two new geometries of pylon equipped with electrodes were proposed and experimentally tested. A second version providing a longer discharge length demonstrates stable ignition and intense combustion in a fully discussed fuel mass flow rate. The process of ignition in a supersonic flow and flame front pulsations was described. A reduction in the energy input in comparison with the previously considered configurations of plasma-assisted combustion was also demonstrated.

We present the results of the synthesis of nanoclusters of metallic zinc and its oxide in crystalline quartz implanted with 64Zn+ ions with a dose of 5 × 1016 cm–2 and energy of 40 keV and annealed in oxygen at 400–900°C. Scanning electron microscopy combined with energy-dispersive spectroscopy, Rutherford backscattering spectroscopy and photoluminescence are used for the study. After implantation, separate nanoclusters of metallic zinc with a size of less than 1 μm are detected on the surface and in the surface layer of quartz. During annealing, metallic zinc passes to the phases of its oxide ZnO and silicate Zn2SiO4. After annealing at 700°C (optimal for obtaining the ZnO phase), zinc-oxide nanoclusters smaller than 500 nm are formed in the quartz surface layer. The photoluminescence spectrum exhibits a doublet peak at a wavelength of 370 nm, which is due to exciton luminescence in zinc oxide. After annealing at 800°C, the ZnO phase degrades, and the zinc silicate Zn2SiO4 phase is formed.

Изучена проблема устойчивой работы продольно-поперечного разряда в сверхзвуковом потоке и его параметры. Рассмотрен продольно-поперечный дуговой разряд в воздушном потоке с параметрами M = 2, V ~ 500 м/с, T g = 170 K, P st = 22 кПа. Для получения данных об изменении длины разряда, тока и напряжения во времени использовались высокоскоростная съемка и запись осциллограмм. Исследована динамика разряда постоянного тока и описаны связи между его геометрическими и электрическими параметрами. Эксперименты были направлены на получение подробных данных о влиянии межэлектродного расстояния и тока на длину разряда и, соответственно, на напряжение и выделяемую мощность, а также на определение типичных частот перепробоя в зависимости от параметров разряда. Также было определено падение напряжения в приэлектродных слоях.

В последние годы ведутся активные исследования электрических разрядов, используемых для воспламенения топливно-воздушной смеси и стабилизации фронта горения [1]. Для продольно-поперечного разряда постоянного тока было установлено, что процесс повторного пробоя происходит при необычно низком напряжении разряда. Этот процесс является лимитирующим фактором длины разряда в сверхзвуковом потоке воздуха. Для описания процесса повторного пробоя было проведено комплексное исследование, включающее эксперимент и численное моделирование в программах FlowVision и PlasmAero [2].

This work is devoted to the study of the properties of a discharge in a supersonic air flow and the problem of determining the temperature of a contracted (thin cylindrical) plasma channel with a radial temperature distribution. The paper considers a direct discharge 30 mm long far from the channel walls in the core of a supersonic flow with the following parameters: Mach number M = 2, flow rate V ~ 500 m/s, stagnation temperature T 0 = 300 K, and static gas pressure P st = 22 kPa. The axisymmetric geometry of the ex-periments with two coaxial electrodes located parallel to the flow was chosen to avoid the appearance of a part of the current channel perpendicular to the flow and the corresponding discharge pulsations. The current–voltage characteristic was obtained, and the dependences of the temperature of the electric discharge plasma on the electrical parameters of the discharge were obtained using emission spectroscopy. Also, with the help of shadow visualization and high-speed shooting, an estimate was obtained of the thickness of the thermal cone and the discharge channel and their dependence on the discharge current.

A physical and numerical model of a longitudinal–transverse discharge in a supersonic air flow is presented. The considered model takes into account not only the traditional mechanisms of interaction between the discharge and the flow (convection, diffusion, heat release, thermochemical nonequilibrium), but also the processes of dissociation and ionization in strong reduced electric fields. It is shown that, within the framework of a two-dimensional model of a direct current discharge, the current loop is carried away by the flow until the ionization rate due to a strong reduced electric field in the immediate vicinity of the electrodes provide a sufficient ionization to form an alternative current channel. In this case, a new current loop begins to form, and the old one dies off. The considered process of current reconnection has a periodic character. The current loop lifetime is proportional to the current amplitude.

Results of numerical simulation using Plasmaero CFD code are presented for direct current (DC) discharge in a high-speed airflow. Modelling of plasma was performed using single-fluid MHD approach and detailed plasma-chemistry. As a result of simulation, the dynamics of DC discharge was obtained which corresponds to dynamics of this object registered during previous experimental study including such effect as the discharge re-breakdown. Concentration of atomic oxygen in different parts of discharge and near them was obtained and analysed. The influence estimation of obtained atomic oxygen concentration on the fuel mixture induction time was performed using zero-dimensional calculation. It was shown that atomic oxygen generation by DC discharge dramatically reduce the ignition delay that could be important for combustion stimulation in a high-speed flow.

This paper presents the results of studying the composition, structure, and properties of amorphous SiO x film obtained by electron beam evaporation. This film was implanted by Zn ions with energy of 40 keV and a dose of 3·10 16 cm 2 . Then, annealing was carried out in air at temperatures from 400 to 800 o C with a step of 100 o C for 40 min at each stage. It has been found that, after implantation, metal Zn nanoclusters with a size of about 10 nm are formed on the surface and in the near-surface layer of silicon oxide. During annealing, the implanted layer becomes enlightened, since metallic Zn gradually oxidizes to transparent phases of its oxide ZnO and silicide Zn 2 SiO 4 . After annealing at 700 o C, ZnO nanoclusters and surface craters were revealed on the surface and in the subsurface layer of the SiO 2 film. Keywords: silicon oxide film, electron beam evaporation, Zn implantation, thermal oxidation, nanoclusters, ZnO.

Исследования характеристик электрического разряда в условиях высокоскоростного потока получили широкое развитие с начала 1960-х гг. [1] во многом в связи с острой необходимостью поиска новых эффективных технологий в области горения, аэрокосмической промышленности и преобразования энергии. В последнее время протяженный разряд постоянного тока, или дуговой разряд, рассматривается в основном применительно к задачам управления сверхзвуковым потоком [2], а также в работах по плазменно-стимулированному горению [3].

The supersonic wind tunnel facility SBR-50 at the University of Notre Dame was built in 2015 for experimental research related to shock wave (SW) interactions with obstacles and boundary layers (BL) as well as supersonic combustion and a plasma-based flow control. Currently, the facility provides the following range of flow parameters with a test section area at the nozzle exit of 76.2 × 76.2 mm: Mach number M=2 and 4, total pressure p0= 1–4 bar, stagnation temperature T0= 300–775 K, and typical duration of the steady-state flow t= 0.5–2 s. One distinct feature of the facility is the Ohmic gas heater installed in a long plenum section. Objective of this study is to characterize flow in the SBR-50 facility, specifically the dynamics of the gas temperature. Two measuring methods were applied for collection of a detailed dataset: thermocouple measurements and schlieren-based thermal mark (laser spark) velocimetry. The experimental data are compared with 3D Navier–Stokes modelling of the gas parameters over the entire flowpath. Particularly, this study proves that the original facility schematics (the concept of a virtual piston in the plenum) allow for a longer operation with a constant stagnation temperature compared to a constant plenum volume with adiabatic cooling of the stored gas.