Vol 43, No 12 (2017)
- Year: 2017
- Articles: 27
- URL: https://journals.rcsi.science/1063-7850/issue/view/12832
Article
Plasma-Immersion Formation of High-Intensity Ion Beams
Abstract
For the first time, the possibility of forming high-intensity beams of low-energy metal and gas ions is demonstrated experimentally. The use of a hybrid system for ion-beam formation including plasmaimmersion extraction and ion acceleration and their subsequent ballistic focusing in an equipotential space with neutralization of the space charge of the beam made possible the pulse-periodic formation of titanium and nitrogen ion beams with an ion-current density of more than 1 A/cm2 and a pulsed power density of 2.6 kW/cm2.
Dynamics of Changes in the Infrared Spectrum of Distilled and Heavy Water upon Exposure to an Electron Beam of Nanosecond Duration
Abstract
The absorption spectra of distilled and heavy water upon exposure to an electron beam of nanosecond duration are investigated. The changes in the absorption spectrum of distilled water after exposure to an electron beam are that the absorption band of valence vibrations of the OH groups becomes broadened, the amplitude of the valence asymmetric band increases, and a shift of the absorption maximums toward shorter wavelength frequencies and an increase in the amplitudes with insignificant band broadening are observed for absorption bands comprised of the sum of deformation and libration vibrations of water molecules and the deformation band of water. The changes in the absorption spectrum of heavy water after its irradiation with an electron beam consist in that the band of valence vibrations of the OH groups of the H2O and HDO molecules is broadened, while the absorption band of the OH overtones of the deformation vibrations of the HDO molecule becomes stronger and the absorption range is preserved. A shift of the absorption maximum toward higher frequencies is observed for the deformation vibrations of the H2O and HDO molecules of heavy water, and the maximum of deformation vibrations of the D2O molecules remains unchanged.
Structural Properties of CdxHg1–xTe Solid-Solution Nanoparticles
Abstract
It is shown that CdxHg1–xTe solid-solution nanoparticles can be produced by ball milling, but their presence is masked by larger particles. The methods of laser-correlation spectroscopy and X-ray-diffraction analysis have been used to study the structure of the nanoparticles and their size distribution. The presence of a compositional disordering of the solid solution structure was experimentally confirmed.
The Effect of Krypton Consumption through the Accelerator Channel on Thrust Efficiency of a Morozov’s Stationary Plasma Thruster
Abstract
Morozov’s stationary plasma thrusters (SPTs) operating on xenon have been successfully used in space technology for many years. At the same time, due to the high cost of xenon, now there is an increased interest in alternative working substances. One of them is krypton. Therefore, research has been conducted earlier on the features of operation and characteristics of SPTs using krypton, which have showed that they are traditional for SPTs. Here, we consider the results of studying the effect of krypton consumption on the thrust efficiency of SPTs. The importance of these results is determined by the fact that they determine the appropriate ranges of SPT regimes when working on krypton.
The Structure of a Hypersonic Air Flow near a Plane Surface at Various Intensities of Magnetogasdynamic Interaction
Abstract
This Letter presents a systematization of the effects observed in experiments on the magnetogasdynamic interaction near the surface of a plate in a high-speed gas flow. Ranges of the hydromagnetic-interaction parameter determining various levels of influence on the shock-wave structure of the flow are established.
Detection of Alfvén Oscillations on the Globus-M Tokamak Using the Doppler Backscattering Method
Abstract
The method of Doppler backscattering (DBS) has been applied for the study of Alfvén oscillations in the tokamak plasma for the first time. The oscillations of the plasma rotation velocity at the Alfvén frequency have been able to be registered using DBS during the studies on the Globus-M spherical tokamak. The area of the development of Alfvén instability has been determined. The measurement of the amplitude of rotation velocity oscillations has allowed the estimation of the absolute values of the amplitudes of the oscillations of the electric and magnetic fields of Alfvén oscillations in the region of their existence in the plasma-discharge volume in tokamak.
Asymmetry of Ceramic Destruction under a High-Velocity Impact
Abstract
Destruction of ceramic barriers under an axisymmetric high-velocity impact has been studied experimentally. The results of the investigations testify to the existence of a significant influence of the structure of ceramic materials on the process of their destruction. The process becomes asymmetric, which can lead to rotation of the impactor with conservation of its initial direction of motion. There are still no models describing the asymmetric character of high-strength ceramic destruction. The probabilistic approach to describing strength characteristics of materials is a possible approach to creating such models.
Increasing the Luminescence Yield of Zirconia
Abstract
The effect of high-temperature treatment in vacuum in the presence of carbon as a reducing agent on the luminescent properties of zirconia is studied. It is shown that an increase in the intensity of pulsed cathodoluminescence at 480 nm and thermoluminescence in the dominant peak at 500 K is due to the thermochemical coloration of the initial samples with the formation of oxygen vacancies detected by electron paramagnetic resonance. The described procedure for increasing the luminescence yield of ZrO2 can be applied when it is used in optoelectronics, photonics, and radiation dosimetry.
A Study of the Thermovoltaic Effect in Heterostructures Based on Sm1–xGdxS Solid Solutions
Abstract
The influence of doping of samarium monosulfide with gadolinium has been investigated. Experiments have been carried out in the temperature range of 300–450 K. A decrease in the effect value with increasing gadolinium content in the Sm1–xGdxS heterostructure with x ranged from 0 to 0.13 has been found and explained. Formulas for calculating the output signal in dependence of the doping value have been derived.
The Effect of Liquid Viscosity on the Formation of Thermocapillary Structures
Abstract
An experimental study of the formation of thermocapillary structures at low Reynolds numbers and temperature gradients at the surface of the film in a wide range of the liquid viscosity is performed. The data on the distance between the jets are generalized. It is demonstrated that the transverse dimension of the structures is determined by the capillary constant and does not depend on either the liquid viscosity or the flow rate (Reynolds number of the film).
Photothermal Infrared Radiometry in Experimental Studies of the Pyroelectric Properties of Bulk Materials
Abstract
A simple and efficient method for determining the pyrolelectric coefficients of ferroelectric and pyroelectric bulk materials by taking into account the heat exchange of a sample with the environment is proposed on the basis of the radiometric registration of the variation dynamics of the temperature of the surface when it is exposed to laser radiation in the form of a temporal step.
Thermodynamic Analysis of the Conformational Stability of a Single-Domain Therapeutic Antibody
Abstract
The stability of a new single-domain therapeutic antibody to the ErbB3 receptor was studied by fluorescence spectroscopy at different concentrations of a denaturing agent and temperatures. The analysis of experimental denaturation curves allowed us to build a complete thermodynamic model of unfolding and to determine all parameters of the transition: ΔG = 8.5 kcal mol–1, Tm = 76°C, ΔHm = 107 kcal mol–1, ΔCp = 1.8 kcal K–1 mol–1. The obtained data evidence the high stability of the antibody in a broad range of conditions, which is essential for further structural and functional studies and possible therapeutic application.
Modification of the Magnetic Properties of α-Fe2O3 Powders by Ultrasonic Processing
Abstract
Hematite (α-Fe2O3) powders after ultrasonic treatment (UST) in the regime of cavitation in aqueous suspension and in that with an organic component (albumin protein) have been studied by Mössbauer spectroscopy and ferromagnetic resonance techniques. It is established that the UST in aqueous hematite suspensions with albumin results in the formation of a new magnetic phase with parameters coinciding with those of the α-Fe metallic phase.
The Formation of Carbide-Free Bainite in High-Carbon High-Silicon Steel under Isothermal Conditions
Abstract
It is shown that a carbide-free bainite structure can be formed in high-carbon steel of the Fe–Si–Mn–Cr–V system using a traditional furnace facility. The structural aspects of bainitic transformation developing under isothermal conditions at 300°C have been studied by the methods of X-ray diffraction and transmission electron microscopy. Orientation relationships between crystalline lattices of γ and α phases have been established. A superequilibrium carbon concentration in the bainite α phase has been determined.
Peaking of Optical Pulses in Vertical-Cavity Surface-Emitting Lasers with an Active Region Based on Submonolayer InGaAs Quantum Dots
Abstract
Vertical-cavity surface-emitting lasers with an active region based on submonolayer InGaAs quantum dots with an oxide-aperture diameter of ~1 μm have been studied. It is established that peaking of the output optical pulses to 50–100 ps can be achieved by pumping these lasers with 10–100 ns electric pulses at a repetition frequency of 10–100 kHz.
An Organic Memristive Element Based on Single Polyaniline/Polyamide-6 Fiber
Abstract
Conducting hybrid polyaniline-coated polyamide-6 fiber has been obtained and used as the basis for an organic memristive element. The proposed device exhibits resistive switching with a continuous character of conductance variation. The results show that the proposed organic memristor can be used for creating three-dimensional stochastic networks based on hybrid nonwoven materials.
The Influence of the Shape of Model Hydrometeors on the Formation of Discharge between an Artificial-Thunderstorm Cell and the Ground
Abstract
We have experimentally studied how arrays of model coarse hydrometeors influence the initiation and propagation of discharge between an artificial-thunderstorm cell of negative or positive polarity and the ground. It is established for the first time that the probability of initiation and stimulation of a channeled discharge between negatively or positively charged cloud and the ground significantly depends on the shape and size of coarse hydrometeors occurring near the thunderstorm cell boundaries. The obtained results can be used in developing methods for the artificial initiation of the cloud–ground type lightning of both polarities and targeted discharge of thunderstorm clouds.
Interfacial Stresses and the Anomalous Character of Thermoelastic-Deformation Curves of a Cu–Al–Ni Shape-Memory Alloy
Abstract
Thermoelastic-deformation curves of a single-crystalline Cu–13.5 wt % Al–4.0 wt % Ni shapememory (SM) alloy have been studied. Cyclic temperature variation in a 300–450 K interval revealed an anomalous character of thermoelastic hysteresis loops with regions of accelerated straining at both heating and cooling stages. The observed phenomenon can be used for increasing the response speed of SM-alloy based drive and sensor devices. Analysis of this phenomenon in the framework of the theory of diffuse martensitic transformations showed that the anomalous character of thermoelastic hysteresis loops may be related to the influence of interfacial stresses on the dynamics of martensitic transformations in these SM alloys.
Optical Diagnostics of WSe2 Monolayers
Abstract
WSe2 films have been studied by the method of second harmonic generation (SHG) in the 1200–1420 nm wavelength range at room temperature. Preliminary investigations of photoluminescence spectra and atomic force microscopy showed that the film consists of extended microcrystals and has a thickness of about 1 nm, which corresponds to a single monolayer. The SHG intensity spectrum showed the presence of a 1s (B)-exciton for 1.95-eV photon energy.
Controlling the Flow past a Semicircular Airfoil at Zero Angle of Attack Using Slot Suction in One or Two Vortex Cells for Attaining Extremal Lift
Abstract
Calculations using multiblock computational technologies and a model of shear-stress transport modified with allowance for the curvature of streamlines in turbulent airflow were performed at a zero angle of attack for a semicircular airfoil containing one or two surface vortex cells with slot suction. The results showed evidence of stabilization of a nearly undetached flow and attainment of an extremal lift of Cy = 5.2 and a lift-to-drag ratio of K = 24 with allowance for energy losses for suction in the vortex cells.
Analysis of an Electromagnetic Wave with Circular Electron Beam Interaction in a Slow-Wave System of “Ribbed-Metal-Rod” Type
Abstract
The interaction of an electromagnetic wave and external annular electron beam in a slow-wave system (SWS) of ribbed-metal-rod type was analyzed and expressions for the equivalent parameters of inductance and capacitance of the structure were found. A dispersion equation describing the excitation of axisymmetric electric waves in the SWS was derived in the impedance approximation. The dispersion characteristics and coupling coefficient have been modeled depending on the geometry of the rod and dielectric permittivity of the material filling the grooves in the SWS structure.
A CVD Diamond-Based Photodetector for the Visible and Near-IR Spectral Range
Abstract
A photodetector for the visible and near-IR spectral range has been created on the basis of a chemical- vapor-deposited diamond modulation-doped with boron. The detected electromagnetic radiation is absorbed in a thin Cr (7 nm)–Au (5.5 nm) bimetallic sublayer deposited on the surface of a modulationdoped diamond film comprising a highly doped (up to 5 × 1019 cm–3) 3-nm-thick delta-layer, low-doped (~1017 cm–3) 800-nm-thick sublayer, and highly doped (1020 cm–3) ~10-μm-thick sublayer with an ohmic Ti(50 nm)/Pt(15 nm)/Au(30 nm) contact. Holes generated in the bimetallic sublayer diffuse into diamond and are accelerated by an electric field in the low-doped sublayer to form a response photocurrent. The ampere/watt responsivity of the photodetector reaches 1 μA/W at a radiation wavelength of 445 nm and 0.18 μA/W at 1.06 μm.
Mechanisms of Current Transfer in Electrodeposited Layers of Submicron Semiconductor Particles
Abstract
Current–voltage (I–V) characteristics of conductance in multigrain layers of submicron particles of silicon, gallium arsenide, indium arsenide, and indium antimonide have been studied. Nanoparticles of all semiconductors were obtained by processing initial single crystals in a ball mill and applied after sedimentation onto substrates by means of electrodeposition. Detailed analysis of the I–V curves of electrodeposited layers shows that their behavior is determined by the mechanism of intergranular tunneling emission from near-surface electron states of submicron particles. Parameters of this emission process have been determined. The proposed multigrain semiconductor structures can be used in gas sensors, optical detectors, IR imagers, etc.
Nonstationary Infrared Testing of Coatings on Exterior and Interior Surfaces of Metal Shells
Abstract
A new method for nondestructive testing of coatings on exterior and interior surfaces of metal shells is proposed that is based on video monitoring of the infrared radiation emitted from the shell excited by shortterm external heating. Computer processing of the measured nonstationary field of temperature distribution on the outer surface allows defects with lateral dimensions on the order of or greater than the shell thickness to be revealed on the inner (inaccessible to observation) surface. Geometric characteristics of these defects can be evaluated.
The Influence of the Surface Neutralization of Active Impurities on the Field-Electron Emission Properties of p-Type Silicon Crystals
Abstract
Correlation dependences between variations of the structural-phase composition, morphology characteristics, and field-electron-emission (FEE) properties of surface-structured p-type silicon singlecrystalline (100)-oriented wafers have been studied during their stepwise high-dose carbon-ion-beam irradiation. It is established that the stepwise implantation of carbon decreases the FEE threshold and favors an increase in the maximum FEE-current density by more than two orders of magnitude. Physicochemical mechanisms involved in this modification of the properties of near-surface layers of silicon under carbon-ion implantation are considered.
Precise Magnetometric Diagnostics of Critical-Current Inhomogeneities in High-Temperature Semiconductor Tapes
Abstract
We present a new precise method of contactless magnetometric determination of the local critical current in high-temperature superconductor (HTS) tapes, which involves (i) measurement of the spatial distribution of a magnetic field of currents induced due to magnetization of the tape by an array of permanent magnets and (ii) processing of the obtained results using a modified algorithm of solution of the Biot–Savart–Laplace inverse problem. The use of an array of permanent magnets is an important feature that distinguishes the proposed method from other existing techniques, since it allows the spatial distribution of critical current to be thoroughly analyzed over the entire tape area.
The Catalytic Effect of Electronegative Additives on Removal of Perchloroethylene Vapor from Air by Pulsed Corona Discharge
Abstract
It is established that electronegative additives (CCl4, freon-113) produce a catalytic effect on the conversion of volatile organic compounds (VOCs) under the action of atmospheric-pressure nonequilibrium plasma generated in pulsed corona discharge. At concentrations below 0.1%, these additives significantly decrease the discharge current, but the energy efficiency of the process of VOC removal from air increases. The catalytic effect of electronegative additives on the VOC conversion in air and nitrogen is quantitatively demonstrated in the case of perchloroethylene C2Cl4 (PCE) vapor removal. The addition of 0.085% CCl4 to air reduces the energy consumption for PCE removal at initial concentration of 0.09% by half (from 12 to 6 eV per molecule) at a 63% degree of cleaning. Mechanisms explaining the active inf luence of electronegative additives on the discharge current and the process of impurity removal are suggested.