Features Of Thermal Processes Research Articles

Features of thermal processes and the influence of pulsed heating of surface layers of titanium on the diffusion transfer of dopants during high-intensity ion implantation

Methods for modification of surface and near-surface layers of materials and coatings by ion beamshave prospects for application in many fields of science and technology. The method of high-intensityimplantation by high-power density ion beams with submillisecond duration involves significantpulsed heating of the irradiated target’s surface layer, followed by its rapid cooling due to heatremoval into the material due to thermal conductivity and the implementation of repetitively-pulsedradiation-enhanced diffusion of atoms to depths significantly exceeding the projective ion range. Thispaper considers features of thermal processes and the effect of pulsed heating of near-surface titaniumlayers on diffusion transfer under conditions of synergy of high-intensity titanium ion implantationand energy impact of a high-power density repetitively-pulsed beam on the surface to increase iondoping depth due to radiation-enhanced diffusion under conditions of limited heating of the entiresample. The paper presents the data of numerical simulation of dynamic changes in temperature fieldsin titanium and titanium self-diffusion under the action of ion beams with a submillisecond durationand a pulse power of tens of kW/cm2 and fluence of ions in a pulse 1.25×1015 ion/cm2.

Some Features of Thermal Processes in Heating Systems with Woven Electric Heaters

Some Features of Thermal Processes in Heating Systems with Woven Electric Heaters

Physical principles of development of magneto-levitation systems based on the second generation high temperature superconducting composites (Review)

An overview of experimental and theoretical studies of the characteristics of maglev systems using high-temperature superconductors (HTSC) is presented. Materials used in maglev technologies, namely bulk superconductors and HTSC tape composites, are considered. The main experimental data obtained on both bulk and tape superconductors assembled in stacks of various configurations are demonstrated. The factors influencing the magneto-force characteristics are analyzed: geometric parameters, the influence of external alternating magnetic fields, temperatures, relaxation phenomena. A significant part of the review is devoted to the description of various methods for calculating maglev systems, including those based on stacks of HTSC composites. The features of thermal processes in maglev systems with cryocooler and nitrogen cooling are considered. General recommendations for the creation of optimal maglev systems based on tape HTSC composites are given. Keywords: magnetic levitation, high-temperature superconductors, strip composites, levitation force, lateral force, methods for calculating magnetic force characteristics.

Физические принципы создания магнитолевитационных систем на основе высокотемпературных сверхпроводящих композитов второго поколения (Обзор)

An overview of experimental and theoretical studies of the characteristics of maglev systems using high-temperature superconductors (HTSC) is presented. Materials used in maglev technologies, namely bulk superconductors and HTSC tape composites, are considered. The main experimental data obtained on both bulk and tape superconductors assembled in stacks of various configurations are demonstrated. The factors influencing the magneto-force characteristics are analyzed: geometric parameters, the influence of external alternating magnetic fields, temperatures, relaxation phenomena. A significant part of the review is devoted to the description of various methods for calculating maglev systems, including those based on stacks of HTSC composites. The features of thermal processes in maglev systems with cryocooler and nitrogen cooling are considered. General recommendations for the creation of optimal maglev systems based on tape HTSC composites are given.

Electrothermal models of structural elements of radioelectronic device

The paper considers basic features of thermal processes in structural modules of radioelectronic device (cell, microassembly) and elements of their electronic structure. The efficiency factors of modules and the indicators of energy performance of resistors, capacitors, and inductors were analyzed on the basis of models of equivalent two-pole networks. The mathematical model of microassembly thermal field was proposed and the analytical equation for determining temperatures of all its elements was derived.

Analysis of investigations of electric fields in different media and conditions

Based on the analysis of scientific-technical literature, the development of investigations and application of electric (electrostatic) fields in liquid and gaseous media in earth and space conditions is shown. A course of further investigations of electric wind in liquid and gaseous hydrocarbon fuels and coolants under the conditions of their natural and forced convection in wide ranges of pressure and temperature parameters with visualization of the characteristic features of thermal processes with the aid of Toepler’s optical device is traced.

Nonlinear effects in media heated by electromagnetic radiation

The features of thermal processes in dielectric absorbing media heated by high-frequency electromagnetic radiation are investigated. It is shown that the temperature dependence of the absorption coefficient of the electromagnetic radiation can result in the development of nonlinear effects: progressive heating in a regime with peaking and localization of the heating region, heating in a regime of lightening of the medium, and formation of quasistationary temperature waves.

Thermal regimes for super-high-frequency heating of dielectrics

The features of thermal processes in a dielectric under the action of a super-high-frequency electromagnetic field are studied. It is shown that the non-linear heat evolution due to the absorption of electromagnetic energy can result at a critical temperature in the development of a nonsteady thermal regime in the sample. For bodies of different geometry, the relationship is found between the critical temperature and the threshold value of the power of super-high-frequency generation and thermophysical properties of the dielectric and conditions of heat exchange with the surrounding medium.