arXiv subjects

Yuri Kornyushin

Publications and source records attributed to Yuri Kornyushin.

31 records · Page 2Linked to original sources

arXiv2007

An attempt to control a manmade nuclear fusion

A detailed simple model is applied to study a high temperature hydrogen plasma ball. It is assumed that the ions and delocalized electrons are distributed randomly throughout the charged plasma ball (extra/missing charge is assumed to be found in a thin layer on the surface of a ball). The energy of the microscopic electrostatic field around the ions is taken into account and calculated. It is shown in the framework of the model that charged hydrogen plasma ball can be stable as a metastable state, when subjected to external (atmospheric) pressure. Equilibrium radius of a ball, the barrier and the enthalpy of the equilibrium ball are calculated. It looks like the charged plasma ball in a metastable equilibrium should be used to conduct controllable nuclear fusion. Changes in the electric charge can be used to control the volume of a plasma ball.

physics.plasm-ph↗

arXiv2007

A model for a plasma ball

A detailed simple model is applied to study a high temperature plasma ball. It is assumed that the ions and delocalized electrons are distributed randomly throughout the charged plasma ball (extra/missing charge is assumed to be found in a thin layer on the surface of a ball). The energy of the microscopic electrostatic field around the ions is taken into account and calculated. It is shown in the framework of this model that regarded charged plasma ball can be stable as a metastable state, when subjected to an external (atmospheric) pressure. Equilibrium radius of a ball is calculated.

physics.plasm-ph↗

arXiv2007

A jelly model for a ball of an extremely hot plasma

A simple model is applied to study a high temperature rather dense plasma ball. It is assumed that the ions and delocalized electrons are distributed uniformly throughout the ball, and extra/missing charge is found in a thin layer on the surface of a ball. It is shown in the framework of this model that regarded plasma ball can be relatively stable as a metastable state. Calculations show that electrostatic forces, repulsive forces between the ions, and atmospheric pressure can provide stability of a plasma ball. Presented model could be useful to understand the nature of a ball lightning.

physics.plasm-ph↗

arXiv2007

Donor type semiconductor at low temperature as maser active medium

In some semiconductors donor impurity atoms can attract additional electrons, forming negative donor impurity ions. Thus we have 3 energy levels for electrons: zero energy levels at the bottom of the conductivity band, negative energy levels of the bounded electrons of the negative donor impurity ions, and deeper negative energy levels of the outer electrons of the neutral donor impurity atoms. So the donor impurity atoms could serve as active centres for a maser. The maximum achievable relative population is 0.5. Typical wavelength of the generated oscillation is 0.14 mm; three level scheme could be realized at rather low temperatures, considerably lower than 6 K.

cond-mat.mtrl-sci↗

arXiv2007

Theoretical introduction to express way of the complex determination of the thermophysical parameters of metals

A method to measure thermophysical characteristics (TPC) of conductive materials is described. The method is based upon controlled bulk (e.g., Ohmic) heating and measurement of the averaged over the volume of a sample temperature and the temperature of the surface of a sample. To measure averaged over a sample volume temperature a dilatometric technique could be used and surface temperature could be measured by x-ray method. This allows one to avoid distortion of the temperature field by the thermocouples and directly takes into account heat losses from the surface of a sample. The treatment of the experimental data should be based upon theoretical calculations presented in this paper. The measured values of the averaged over the volume of a sample temperature and a surface temperature allow for the calculation of TPC of the material. The experimental data obtained on the iron-based materials prove the high accuracy of the described approach [1-3].

cond-mat.mtrl-sci↗

arXiv2007

An introduction to the polaron and bipolaron theoretical concepts

A simple model for the autolocalization of a free charged particle is presented. The polarization well in the model is deep enough for only one localized level. In dielectric materials with a sufficiently large dielectric constant, two charged identical particles can be localized in one polarization potential well, forming a bipolaron. Although several localized levels can be found in more realistic self-consistent models of this type, the more realistic theories require a high level of knowledge of mathematics. Hence, the proposed model can serve as an introduction to the ideas and concepts of autolocalized states.

cond-mat.mtrl-sci↗

arXiv2007

Microcracks and inhomogeneously distributed defects in solids

A conception of inhomogeneous locally random distribution of microdefects in crystalline solids is proposed. A method to calculate some physical properties of solids, containing inhomogeneously distributed defects, is developed. A contribution of this inhomogeneity to a series of physical properties is calculated and discussed. This contribution exceeds that of homogeneously distributed defects by the orders of magnitude. A contribution of the inhomogeneity to electric conductivity, Hall effect and magnetoresistance is calculated. Elastic energy and volume of inhomogeneously dislocated crystal are regarded. It was shown that the relaxation of the elastic energy of random dislocations during propagation of a crack facilitates the process. These results explained a phenomenon of lamination of overdeformed metals.

cond-mat.mtrl-sci↗

arXiv2007

Local and regular plasma oscillations in bulk donor type semiconductors

Restoring force acts on the electronic cloud of the outer electrons of a neutral or charged impurity atom when it is shifted relative to the inner charged core. Because of this the dipole oscillation arises, which influences considerably the dispersion law of the plasma oscillation in bulk donor semiconductors. Assuming that only one transition of the outer electron from the ground state to the first excited state is essential, the dispersion law is calculated. It is shown that calculated dispersion law consists of two separate branches, one of them originates from the regular plasma oscillation of the free electrons of a conductivity band, and the other one stems from the local oscillation of the outer electrons bounded to the impurity atoms.

cond-mat.mtrl-sci↗

arXiv2007

The plasma spectrum effect on acoustic wave amplification by carrier drift in semiconductors

The effect of plasma oscillations on acoustic wave amplification by carrier drift in semiconductors is discussed. A continuum theory is developed on the basis of hydrodynamical equations for the conduction electrons, the equations for the elastic vibrations of the crystal, and the Poisson equation. It is shown that if the plasma frequency is much lower than the reciprocal value of the electron relaxation time for the scattering on phonons and impurities, the results are in agreement with available calculations based on the electrical conductivity - diffusion equation. However, in the opposite case the amplification factor is orders of magnitude larger compared to the value predicted by those calculations, while the optimum drift velocity is much smaller.

cond-mat.mtrl-sci↗

arXiv2007

Studying Thermodynamics of Metastable States

Simple classical thermodynamic approach to the general description of metastable states is presented. It makes possible to calculate the explicit dependence of the Gibbs free energy on temperature, to calculate the heat capacity, the thermodynamic barrier, dividing metastable and more stable states, and the thermal expansion coefficient. Thermodynamic stability under mechanical loading is considered. The influence of the heating (cooling) rate on the measured dynamic heat capacity is investigated. A phase shift of the temperature oscillations of an ac heated sample is shown to be determined by the relaxation time of the relaxation of the metastable nonequilibrium state back to the metastable equilibrium one. This dependence allows one to calculate the relaxation time. A general description of the metastable phase equilibrium is proposed. Metastable states in AB3 alloys are considered. Reasons for the change from the diffusional mechanism of the supercritical nucleus growth to the martensitic one as the heating rate increases are discussed. The Ostwald stage rule is derived.

cond-mat.mtrl-sci↗

arXiv2007

Kinetic Theory of the Heat Capacity of Two-Level Systems

It is shown that measured heat capacity depends on the rate of the temperature variation and on the initial state of a system. It is calculated here in the framework of two-level model. Fenomenological approach gives the same results.

cond-mat.mtrl-sci↗

arXiv2007

Uniform plasma oscillations in ellipsoid of conductive material

The influence of the shape of a sample on the type of uniform dipole collective electrons oscillations is discussed. In samples of a bulk shape uniform bulk dipole oscillation (Langmuir oscillation) cannot exist. It exists in samples of a thin slab shape only. As uniform bulk dipole oscillations cannot penetrate ellipsoidal samples of conductive material, they exist in the surface layer of a sample only (Mie oscillations). Frequencies of Mie oscillations are alculated for a sample of the shape of an arbitrary ellipsoid.

cond-mat.mtrl-sci↗

arXiv2007

Thermodynamic Theory of Sintering and Swelling

The General Thermodynamic Theory of Sintering, formulated by the author in 1998 is given. This theory is applied to the problem of swelling of materials under conditions of radiation. Driving forces, caused by the presence of the evolution of heat in the volume of a sample (electric contact, hf, inductive heating or penetrating radiation, e.g., neutrons could be the sources of the heat in the bulk of a sample) are considered. The influence of these driving forces on sintering, structure and properties is discussed. The role of mobile and immobile dislocations, grain boundaries, and pores is regarded. Cycling and pulsing regimes of sintering are investigated. A mesoscopic approach, described in present paper, which had been used for years to solve sintering problems, also could help solving problems of nucleation, decomposition, and other problems in the theory of alloys. Described relaxation time technique could help simplifying calculations and give more clear physical picture. Bulks heating driving forces, important for small size objects of microelectronics or/and heat evolving elements in nuclear reactors, are important also for the problems of nucleation and decomposition in these objects.

cond-mat.mtrl-sci↗