Influence of the thermo-field electron emission from the cathode with a thin insulating film on the film emission efficiency and ignition voltage of the townsend gas discharge
A model of the thermo-field electron emission from the metal cathode with a thin insulating surface film at
temperatures of 200–400 K is developed. An expression for the film emission efficiency in the gas discharge is
obtained. The efficiency is equal to the fraction of electrons emitted into the film from the metal substrate,
which enter the discharge volume and increase the effective secondary-electron emission yield of the cathode.
It is shown that the thermo-field mechanism of electron emission influences noticeably the ignition voltage of
the low-current discharge with such cathode at rather low temperatures exceeding the room temperature by
less than 100 K.
The heat transfer process is simulated in a nano-sized cone-shaped cathode. A model of heat transfer is constructed using the phase field system and the Nottingham effect. We consider influence of the free boundary curvature and the Nottingham effect on the heat balance in the cathode.
The factors affecting the thermal degradation of a single silicon field-emission pointed cathode during the take-off of the emission current are described experimentally. The results of the numerical modeling of the temperature dynamics of the field-emission cathode in conditions of the presence of a free interface between the liquid and solid phases allowing for the surface tension are described.
An approximate analytical expression for the ion current density near the cathode in glow discharge is obtained in the presence of a periodic relief of small amplitude and an insulating oxide film of varying thickness on its surface. It is found that ion focusing at the cathode sections with the minimum film thickness, located on any parts of the surface relief, takes place, resulting in an increase of the film thickness non-uniformity with time. Therefore, under the existence of an oxide film on the cathode, its sputtering in glow discharge is determined mainly by the film thickness non-uniformity and not by the surface relief.
The materials of The International Scientific – Practical Conference is presented below.
The Conference reflects the modern state of innovation in education, science, industry and social-economic sphere, from the standpoint of introducing new information technologies.
It is interesting for a wide range of researchers, teachers, graduate students and professionals in the field of innovation and information technologies.
The ХХV International scientific – technical conference “Foundry 2018” was held of the 18-20 April 2018 at “Rostov” hotel in the city of Pleven, Bulgaria. Its aim is to provide a meeting place for scholars from different countries to present their scientific achievements and to discuss the problems of casting production.
In the paper the content of individual elements (Fe, Co, Zr, Ca and F) contained in nanocomposites FeCoZr ferromagnetic alloy in the CaF2 transparent ceramics dielectric matrix, depending on the content of the metal phase x was determined by the X-ray diffusion microanalysis (EDX) method. The nanocomposites were made by sputtering by argon ions. Investigations of changes in the chemical composition of nanocomposites under the influence of high-temperature treatments were carried out using the thermogravimetry method in the temperature range from 25 °C to 1000 °C with a temperature increase rate of 10 °C/min. On the basis of the research, a model of changes of the structural-phase state of nanogranular layers of ferromagnetic alloy Fe45Co45Zr10 in the transparent ceramics CaF2 matrix occurring under the influence of high-temperature treatments was proposed.
The article describes the formulation and solution of the axisymmetric problem of quantify SSS composite cylinder with a sandy soil under the influence of an external load of plate foundations, analytical and numerical methods based on elastic-plastic properties of soils. Shown that the axial force on the composite cylinder is distributed between the sand-pile and the surrounding previously compacted weak soil in proportion to their stiffness and diameter ratio. It is noted that at a certain load in the sand pile, plastic deformations occur as a result of which the stresses are redistributed, and the total deformation of the composite cylinder develops nonlinearly. It is shown that, depending on the calculation model adopted in the sandy soil pile at stresses close to the ultimate value various forms of destruction forming, including the barrel at different levels. Stresses that this phenomenon was observed for the first time and requires further research and theoretical basis.
This work describes the monitoring of structural reinforced concrete elements with additional strengthening elements. For reinforcing, the metal channels with rigid connection to the reinforced concrete beams were used. Subject. This work describes the study of potentialities of geodetic and strain-measuring monitoring during the operation of strengthened concrete beams with additional reinforcement elements when static loading. Purpose. Development of monitoring systems for factual work of reinforced concrete beams; assessment of reliability of the results obtained. The initial materials for this study were the data obtained from geodetic and strain-measuring monitoring in the process of a stage-by-stage static loading of reinforced concrete beams. Results. The time dependences of the deflection of reinforcement elements in the structures under reinforcement are obtained when their stage-by-stage static loading. Conclusions. The possibility of the studied methods application is found to be proved for the monitoring of concrete structures with additional reinforcement elements.
This volume presents new results in the study and optimization of information transmission models in telecommunication networks using different approaches, mainly based on theiries of queueing systems and queueing networks .
The paper provides a number of proposed draft operational guidelines for technology measurement and includes a number of tentative technology definitions to be used for statistical purposes, principles for identification and classification of potentially growing technology areas, suggestions on the survey strategies and indicators. These are the key components of an internationally harmonized framework for collecting and interpreting technology data that would need to be further developed through a broader consultation process. A summary of definitions of technology already available in OECD manuals and the stocktaking results are provided in the Annex section.