HIGH-ENERGY AND ACCELERATOR PHYSICS, PHYSICS OF HIGH-TEMPERATURE PLASMA
This paper presents the test results of a radiofrequency (RF) plasma generator, developed for neutral beam injectors. A water cooled faraday screen is installed into the generator for multi-second pulse operation. Consistent operation achieved for 20-second long pulses with input power of 38 kW is described. The density of the ion current was measured. The experiments were conducted to measure the density of the ion current at the driver’s output and to evaluate the heating of the driver’s elements. Main factors affecting the power losses were determined. The power loss caused by the eddy currents in the driver’s clamping flanges were reduced.
PHYSICS OF A FLUID, NEUTRAL AND IONIZED GASES
The paper presents the results of experimental studies of scenarios of diffusion combustion of a microjet of hydrogen flowing out of a cylindrical micronozzle with a diameter of 200 μm. The hydrogen microjet is ignited near the nozzle exit and at a distance. The experimental data are compared with the data previously obtained, and the results are expressed in dimensionless parameters (in terms of Reynolds numbers). It is established that the stabilization of flame during the outflow of a circular micro jet of hydrogen is associated with the presence of heating of the nozzle by a spherical flame region covering the nozzle section. The hysteresis of the diffusion combustion process of circular hydrogen microjets is shown depending on the ignition location of the microjet (near or far from the nozzle exit) and the change in the flow rate (growth or decrease).
Methods for restoring aerodynamic forces based on the use of measurement data by balance elements and an accelerometer have been expanded. A signal processing method has been developed that makes it possible to correct the measurement data of balance elements using additional data on the acceleration of support elements. Examples of the application of the proposed method under the conditions of a pulsed wind tunnel in experiments on massive models, both with constant and decreasing flow parameters during the test, are given. An increase in the measurement accuracy of single-component force-measuring sensors is shown.
SOLID-STATE AND SEMICONDUCTOR PHYSICS, PHYSICS OF NANOSTRUCTURES
We investigated the physicochemical aspects of the gas-phase nanopowder synthesis using a cyclic compression reactor. Compression of precursors (methane, ethylene, acetylene) under conditions close to the adiabatic ones in the atmosphere of buffer monatomic gases (argon, helium, neon) was used. The influence of pressure in the reactor and volumetric ratio of precursor/buffer gas mixture on the composition, morphology, and structure of carbon-containing particles representing the pyrolysis product was studied. Complete pyrolysis was observed for all studied precursors, but under different conditions. Thermal decomposition of methane, having the minimum enthalpy of formation, was observed in an atmosphere with argon content 97.5 % at a peak pressure more than 10 MPa. Helium showed limited possibilities for thermal relaxation under the conditions of fast reactions (< 50 ms). Only acetylene with the maximum enthalpy of formation was decomposed in the atmosphere of helium. The solid reaction products represented black colored powders with a bulk density of 20–30 mg/cm3. The powders were examined by transmission electron microscopy and scanning electron microscopy, Raman scattering and X-ray diffraction analysis. The particles represent globular bulbous structures up to 100 nm in size, either hollow or filled inside. X-ray diffraction analysis showed the presence of a graphite-like structure with crystallite sizes less than 10 nm in all samples. Raman analysis showed mainly sp2 hybridization of carbon. The cyclic compression method demonstrates wide range of opportunities for the pyrolysis of hydrocarbons aiming at the production of a variety of carbon structures, which enables for the fine tuning in terms of the yield of products of the required morphology for practical use.
In the present work, an experimental study of the effect of aluminum and boron carbide powder mixture composition on the microstructure and basic properties of the cold sprayed coatings was carried out for the first time. A series of coatings deposited on stainless steel substrates was obtained. The microstructure of the deposited coatings was analyzed by scanning electron microscopy and X-ray diffraction analysis. The microhardness and bonding strength of the coatings were measured. It was shown that an increase from 0 to 72 vol.% in the boron carbide content in the powder mixture leads to an increase in its content from 0 to 15-17 vol.% in the coating, its microhardness – from 46.3 to 72.4 HV0.3, and bonding strength – from 17.4 to 61.4 MPa. The obtained results open up broad prospects for the application of the cold spray method to deposition of functional coatings, which are highly demanded in the nuclear industry.
In this article, an optoelectronic method, technique and technology for obtaining a stabilized electric field using external, natural renewable sources of various types has been developed. The proposed device operates on the basis of the anomalous photovoltaic effect (AFN effect) where the heat of human body is converted into an electric field. It is shown that using the potential of an electric field it is possible to develop individual, autonomously operating micro-miniature optoelectronic devices for various purposes.
EDUCATIONAL AND METHODICAL PROVISION OF TEACHING OF PHYSICS
The article is dedicated to the Chair of Aerophysics and Gas Dynamics of the Physics Department of Novosibirsk State University based at the Khristianovich Institute of Theoretical and Applied Mechanics SB RAS.
The article provides information about the history of formation, development, main recent activities and achieved results of the Analytical and Technological Research Center of the Faculty of Physics of Novosibirsk State University (ATRC NSU) during its 15 years of operation. The main areas of physical research are: modern materials science, nanomaterials, nanotechnologies and technological processes, experimental diagnostics of structures and substances, development of methods for nanostructures fabrication, computer simulation of low-dimensional structures, improvement of the characteristics of solid-state semiconductor electronics, search for materials for storage and transfer of digital information, study of technological properties of low-dimensional semiconductors, catalysts, metamaterials and organic optoelectronics, study of materials and systems for terahertz electronics. Due to the organization of the Shared Research Facilities “High Technologies and Analytics of Nanosystems” (CCU “VTAN”) within the structure, ATRC successfully cooperates with scientific and educational organizations and with industrial companies of the real sector of the economy in the Siberian region, Russia and neighboring countries. The main part of scientific research is carried out by the staff of the youth Laboratory of Functional Diagnostics of Nanoscale Systems for Nanoelectronics (LabFDNS) that contributes to the involvement of students and young employees of NSU into the implementation of relevant in-demand research work, and thus provides them with a high level of training in their chosen specialty.
Information about the resources of the laboratory “AMS Golden Valley” and the state of affairs in accelerator mass spectrometry (AMS) in Russia is presented. The key differences of the AMS method from traditional methods for determining radiocarbon are described, the principle of operation of accelerator mass spectrometers of Russian (unique scientific facility “AMS BINP SB RAS”) and Swiss (MICADAS-28) production is given, and basic information is given about the methods for preparing graphite targets for AMS-analysis.
The article presents the department of nanocomposite materials of the Novosibirsk State University, describing the history of its creation. The reader can also find here some general information about the staff and the courses taught.