Action Of Electron Beam Research Articles

Structure formation in syntactic foam based on metal-coated glass microspheres and polysiloxane under the action of a nanosecond relativistic electron beam

Structure formation in syntactic foam based on metal-coated glass microspheres and polysiloxane under the action of a nanosecond relativistic electron beam

Computational and Experimental Modeling in Magnetoplasma Aerodynamics and High-Speed Gas and Plasma Flows (A Review)

This paper provides an overview of modern research on magnetoplasma methods of influencing gas-dynamic and plasma flows. The main physical mechanisms that control the interaction of plasma discharges with gaseous moving media are indicated. The ways of organizing pulsed energy input, characteristic of plasma aerodynamics, are briefly described: linearly stabilized discharge, magnetoplasma compressor, capillary discharge, laser-microwave action, electron beam action, nanosecond surface barrier discharges, pulsed spark discharges, and nanosecond optical discharges. A description of the physical mechanism of heating the gas-plasma flow at high values of electric fields, which are realized in high-current and nanosecond (ultrafast heating) electric discharges, is performed. Methods for magnetoplasma control of the configuration and gas-dynamic characteristics of shock waves arising in front of promising and advanced aircraft (AA) are described. Approaches to the control of quasi-stationary separated flows, laminar–turbulent transitions, and static and dynamic separation of the boundary layer (for large PA angles of attack) are presented.

All-Water Etching-Free Electron Beam Lithography for On-Chip Nanomaterials.

Electron beam lithography uses an accelerated electron beam to fabricate patterning on an electron-beam-sensitive resist but requires complex dry etching or lift-off processes to transfer the pattern to the substrate or film on the substrate. In this study, etching-free electron beam lithography is developed to directly write a pattern of various materials in all-water processes, achieving the desired semiconductor nanopatterns on a silicon wafer. Introduced sugars are copolymerized with metal ions-coordinated polyethylenimine under the action of electron beams. The all-water process and thermal treatment result in nanomaterials with satisfactory electronic properties, indicating that diverse on-chip semiconductors (e.g., metal oxides, sulfides, and nitrides) can be directly printed on-chip by an aqueous solution system. As a demonstration, zinc oxide patterns can be achieved with a line width of 18 nm and a mobility of 3.94 cm2 V-1 s-1. This etching-free electron beam lithography strategy provides an efficient alternative for micro/nanofabrication and chip manufacturing.

SPECIFIC FEATURES OF PULSED CATHODOLUMINESCENCE UNDER EXCITATION BY NANOSECOND AND SUBNANOSECOND ELECTRON BEAMS

Pulsed cathodoluminescence of crystals and ceramics was excited by runaway electron beams with a duration of 10–12 ps and electron beams with a duration of 2 ns generated in a vacuum diode. The results of comparative studies of their pulsed cathodoluminescence parameters are presented. The luminescence spectrum and the decay kinetics of the bands are shown to coincide in both cases. When excited by a beam of runaway electrons, a lower luminescence intensity is observed. Also in some cases a delay in the appearance of luminescence relative to the onset of the electron beam action was found. The mechanism for the delay appearance under excitation by a runaway electron beam is associated with the process of luminescence rise.

Generation of Plasma with High Calcium Content by Electron Beam Action on Calcium Carbonate-Based and Calcium Sulfate-Based Materials

Generation of Plasma with High Calcium Content by Electron Beam Action on Calcium Carbonate-Based and Calcium Sulfate-Based Materials

Plasma chemical conversion of methane by pulsed electron beams and non-self-sustained discharges

Investigations of methane conversion in atmospheric-pressure mixtures of various composition and temperature, irradiated by pulsed nanosecond electron beams and non-self-sustained discharges initiated by electron beams, were carried out. It was shown that during direct conversion at room temperature, the energy cost of the conversion of one CH4 molecule (5.6 eV molecule−1) was commensurate with that obtained in the experiments with the use of continuous electron beam. The main products of direct conversion were hydrogen and ethylene. If a small amount of oxygen was present in the mixture, methanol was added to the conversion products, which in turn decomposed into CO, CO2 and H2O. The results of numerical simulations and experiments were basically the same. The use of a non-self-sustained discharge increased the degree of direct conversion of methane, but the energy cost of conversion also increased. The main products of carbon dioxide conversion of CH4 (dry reforming) under the action of pulsed electron beam at room temperature were CO, H2, C2H6, and carbon. Energy cost of conversion (12 eV molecule−1) was about two times higher than in the case of direct conversion of methane. However, the use of pulsed electron beam for dry reforming turned out to be energetically more efficient than the use of the most types of discharges. The main products of CH4 oxidative conversion by pulsed electron beam were H2, C2H6, and C2H4. At room temperature, the energy cost of methane conversion without a catalyst was 9 eV molecule−1, whereas the use of Ni catalyst resulted in a seven-fold increase, and the use of NaOH/CaO one—in a 14-fold increase in the conversion efficiency compared to irradiation without a catalyst. When the temperature of the catalysts rised to 623 K, the conversion efficiency increased by another four times. The processes in electron-beam plasma that provide the implementation of the main mechanisms of methane conversion are also discussed in the paper.

Two-level model of the grain boundary diffusion under electron beam action

A two-level model of transition zone formation between a polycrystalline substrate and its protective coating under pulsed electron beam exposure with the isolation of individual grain boundaries at the mesolevel has been proposed. Possible chemical reactions and different nature of diffusion in the volume of the grains and along the grain boundaries are taken into account. Physical processes at the mesolevel are reflected in the thermal macro model for the whole sample. Both diffusion coefficients and chemical reaction rates depend on temperature. The different nature of the transition zone formation process between the coating and the substrate is revealed for grains of different sizes. The modification of coatings from tantalum and from silicon on TiNi-surface is studied as examples. The method for effective properties estimation suggested in this work uses the averaging and the integral rule taking into account the form and size of grains and the composition changing during electron beam treatment.

Атомная структура и оптические свойства слоев CaSi-=SUB=-2-=/SUB=-, выращенных на CaF-=SUB=-2-=/SUB=-/Si-подложках

In this work, we study the growth features, as well as the structural and optical properties of CaSi2 layers formed in the process of successive deposition of Si and CaF2 on a Si (111) substrate with simultaneous irradiation with high energy electron beam. The Raman spectra recorded in the regions of the electron beam action showed peaks characteristic of crystalline CaSi2 layers. The study of the surface morphology of the grown structures demonstrated that, under the chosen synthesis conditions, the formation of CaSi2 layers during electron irradiation occurs according to a two-dimensional layer mechanism. The photoluminescence spectra measured in the region modified by the electron beam have significant differences from the spectra measured outside this region.

Electrical effects in polymers and composite materials under electron beam irradiation

The modern state of experimental and theoretical studies of the radiation-induced conductivity and charging of polymeric dielectrics under the action of electron beams is considered. The effect of the molecular mobility on the transport of excess charge carriers is discussed.

ANALYSIS OF CHANGES IN THE PHASE AND STRUCTURAL STATE OF AN ALUMINUM ALLOY 1933 SURFACE LAYER, MELTED BY A PULSED ELECTRON BEAM

The structural and phase changes in the surface layer of an aluminum alloy 1933 caused by the action of a relativistic pulsed electron beam are studied. The structural and phase state of this layer is determined by the impact action of the electron beam and by the kinetics of crystallization from the melt under ultrafast cooling. The impact of a pulsed electron beam is accompanied by the formation of a developed surface relief and the appearance of microcracks on it. The structure of the modified layer is nonequilibrium. X-ray diffraction studies and the results of energy dispersive X-ray microanalysis made it possible to determine that magnesium oxide inclusions are present in the remelted layer. MgO inclusions are generally uniformly distributed in the remelted layer. The maximum size of MgO inclusions does not exceed 1 μm. The causes and mechanisms of the formation of magnesium oxide during the action of a pulsed electron beam are discussed.

Radiation-Induced epitaxial CaSi2 film growth at the molecular-beam epitaxy of CaF2 on Si

We report on the studies of the 20 keV electron-beam irradiation (current density 50 μA/m2) effects on the epitaxial CaF2 film growth on a Si surface. It was found that, during the CaF2 growth on Si, the area exposed to the electron beam suffers strong modifications, such as in the surface morphology and film chemical composition. With reflection high-energy electron diffraction, atomic force microscopy and Raman spectroscopy, it is shown that the electron beam action leads to the CaSi2 layer synthesis at the interface of the silicon substrate and epitaxially growing CaF2 film.

Increasing the electron beam melting process efficiency in a scull crucible

The paper considers the issues of increasing the efficiency of electron beam scull melting (EBSM) by optimizing the param-eters of electromagnetic stirring (EMS) of the melt. The example of titanium melt preparation process in a copper water-cooled sectional crucible is shown on example of an EMS system consisting of two coils. The analysis of melting and casting technological parameters, as well as modeling of temperature and hydrodynamic processes, are reviewed. The optimum parameters of a liquid metal bath in the formed volume of metal inside the scull are determined, after which the most effective growth of the liquid metal amount could be achieved. The expediency of increasing the efficiency of electromagnetic stirring by controlling the phase shift angle between the electrical voltages fed by the adjacent coils of the crucible electromagnetic stirring system is shown. It has been determined and shown that in the process of melt bath forming, it is advisable to change its motion directions at different stages of the process. The conditions of the highest energy efficiency of the melting process, which are to maintain a moderate thickness of the scull side walls, are investigated. This feature is up to reduce the heat dis-sipation from the melt and also to reduce the intensity and the area of evaporation of the metal under the action of electron beam. This approach also improves the lifetime of the crucible and reduces the risk of accidents. The possibility of reducing the melting time by introducing into the crucible a fixed mass of the melt obtained in another melting tank after preheating the charge with an electron beam to a temperature at which the explosive emission of the melt is eliminated is considered.

Влияние слабого магнитного поля на чувствительность порошкообразного аммината перхлората кобальта различной дисперсности к воздействию сильноточного электронного пучка наносекундной длительности

The paper presents results of the experimental study of the impact of the weak magnetic field in the sensibility of the powder of ammine cobalt perchlorate to the action of the nanosecond-durability high-current electron beam (HCEB). The powder of ammine cobalt perchlorate of two types of dispersity, coarse particles and microparticles, was utilized in our study. We discovered that both weak magnetic field and powder dispersity have a strong impact on the sensibility to the effect of the HCEB.

A Determination of the Relationship between Energies of Vavilov–Cherenkov Radiation and Cathodoluminescence Excited by an Electron Beam in Diamond

The ratio between energies of Vavilov–Cherenkov radiation and cathodoluminescence excited by an electron beam in diamond samples is determined taking into account electron scattering in these samples, energy distribution of beam electrons, ionization losses of the electron energy, and dispersion of the diamond refractive index. Experimental results on measuring spectral characteristics of the glow of natural and synthetic diamond samples under the action of a subnanosecond electron beam with electron energy of up to 200 keV are presented. It is shown that most of the radiation of the diamond samples in the region of 240–750 nm under the action of an electron beam with electron energy of up to 200 keV belongs to cathodoluminescence.

Morphology stability of polymethylmethacrylate nanospheres formed in water–acetone dispersion medium

The aim of this study is to develop a manufacturing technique of polymethylmethacrylate (PMMA) nanospheres to produce a more stable opal template. Water–acetone mixture was used as a dispersion medium to synthesize a PMMA opal structure. Morphology features, IR vibrational spectra and glass transition temperatures of the PMMA nanospheres formed in the water–acetone dispersion medium (nanospheres A) have been studied comparing with the same prepared in distilled water solution without acetone (nanospheres B). A dependence of a shrinkage degree of the nanoparticles on the acetone volume has been investigated. It has been revealed that under an electron beam action the shrinkage degree of the nanospheres A is in the range of 7–16% while the shrinkage of the nanospheres B is 18–25% at the same conditions. The nanospheres A are less flexible and soft as compared to the nanospheres B. Additionally, an ability of the PMMA nanoparticles fabricated in the water–acetone dispersion medium to form the ordered opal structures is demonstrated to be the similar to the nanospheres B.

Оценка соотношения энергий излучения Вавилова--Черенкова и катодолюминесценции, возбуждаемых электронным пучком в алмазе

AbstractThe ratio between energies of Vavilov–Cherenkov radiation and cathodoluminescence excited by an electron beam in diamond samples is determined taking into account electron scattering in these samples, energy distribution of beam electrons, ionization losses of the electron energy, and dispersion of the diamond refractive index. Experimental results on measuring spectral characteristics of the glow of natural and synthetic diamond samples under the action of a subnanosecond electron beam with electron energy of up to 200 keV are presented. It is shown that most of the radiation of the diamond samples in the region of 240–750 nm under the action of an electron beam with electron energy of up to 200 keV belongs to cathodoluminescence.

Surface layer evolution under the external heating

Generalized equation system is written to describe the surface layer evolution under electron beam action. Chemical reactions and porosity evolution are taken into account. The model was used to describe the electron beam treatment of thin layer with varied thickness. The review is made for some previous particular models of electron beam surface treatment with chemical reactions and shrinkage. It was pointed that the model permits the existence of self-sustaining regimes and quasi-stationary technology regimes.

Electron Beam Action and High Charging of Dust Particles

A theory is developed which describes the processes of dust particle charging in the situation when dust particles are subjected to the action of a beam of electrons. It is shown that in this situation it is necessary to consider the electron field emission in addition to the influence of the electron beam on the dust particle. We calculate the current of the electron field emission modified by the Schottky effect and find the steady-state dust particle charge. We show that in the situation considered the electrostatic energy of the dust particle is much smaller than the electron energy in the beam.

Zirconia ceramics processing by intense electron and ion beams

Beam technologies are considered promising for surface modification of ceramics. The processes related to modification of zirconia and alumina-zirconium ceramics properties under intense electron and ion beam action are investigated. The ceramics samples were sintered by the thermal method and processed by electron and ion beams in vacuum. The electron beams had the following parameters: E = 15 keV, current density per pulse, 18 A/cm2, pulse duration, 50 μs, and pulse repetition rate, 0.1 Hz. For ion irradiation, we used C+ ion beams with the following parameters: energy of accelerated ions, 200 keV; current pulse duration, 100 ns; and pulse current densities, 40 and 150 A/cm2. It is shown that radiation processing causes significant changes in the microstructure, phase composition and electrical conductivity of the near-surface layer. It is established that the mechanical properties of irradiated modified ceramic layers depend mainly on the source porosity of the samples before processing. In particular, radiation exposure of low porous ceramics decreases the hardness of the near-surface layers. On the contrary, radiation-exposed highly porous ceramics exhibits increased hardness, which is caused by a local increase in the density of the near-surface layers as a result of fusion.

Substantiation of the Possibility of Predicting Behavior of Solids under Extreme Conditions at Various High-Intensity Impacts

The paper is devoted to the data analysis on the amplitude-time regularities of the dynamic failure process of solids under various types of high-intensity impact in the ranges of nonequilibrium states from 3 × 10−10 to 10−5 s and establishing general regularities of behavior of unstudied materials under extreme conditions. We have analyzed the process of dynamic destruction of solids of different nature using the method of magnetic-pulse loading in the microsecond range of nonequilibrium states, as well as the dynamic failure process for a number of metals in the mode of pulsed volume heating under the action of pulsed relativistic electron beams in the nanosecond and subnanosecond range of nonequilibrium states. It has been shown that, upon using different methods of pulsed loading in the dynamic longevity range, the failure time as a function of amplitude of applied load has an exponential form for various solid materials. This indicates the scaling nature of the destruction process. The foregoing determines the possibility of predicting the behavior of unstudied solid bodies in the dynamic range of nonequilibrium states.