ISSN 0869-6632 (Print)
ISSN 2542-1905 (Online)

численное моделирование

Numerical simulation of oscillations of an electrically charged heterogeneous medium due to inter-component interaction

Aim. The aim of the work is the numerical study of the oscillations of two-phase medium (a mixture of gas and a dispersed phase of solid particles) which caused by electric charge of the dispersed component, and the reciprocal effect of the dynamics of gas and solid particles, as well as the effect of linear size of dispersed particles on the dynamic processes. Methods. With the help of numerical models of electrically charged suspension was modeled in different modes of oscillatory dynamics in a dusty environment.

Features of time­-spatial structure formation of the multiwave cherenkov-­oscillator radiation

The analysis of influence of the reflection coefficient of the electromagnetic field from the cathode on the radiation characteristics of Cherenkov generators was carried out by the methods of computer simulation. It is shown that the optimal parameters of generation can be achieved at the values of the reflection coefficient close to unity.

Method for calculation of lyapunov exponents spectrum from data series

The new method for the calculating of the spectrum of the Lyapunov exponents from data series is proposed. The already known methods of the same thematic are investigated. The Roessler system is given as an example for describing the proposed method. The results of numerical modeling are presented.

Investigation of particularities formation spatially periodic structures of multieddy isothermal electroconvection

Electroconvective ?ow in plane horizontal layer of dielectric liquid due to the crisis of the equilibrium layer stability loss in homogeneous electric ?eld are numerically modeled.

Three-­dimensional simulation of virtode with toroidal cavities

The results of preliminary 3D fully electromagnetic simulation of microwave generator with virtual cathode and external feedback loop (virtode) are discussed in this paper. The feedback is realized by the velocity modulation of electron beam in the accelerating gap of electron gun with the electromagnetic signal taken with output cavity placed in the virtual cathode area.

Noise-­induced phase transitions in competition processes in the external fluctuated media

The influence of external additive homogeneous isotropic field of Gauss fluctuations to evolution of competition processes, which described by Lotka–Volterra equations, where taking into account the mobility of weak population individuals and spatial and temporal fluctuations of resource, has been researched. The numerical simulation of considered model was performed.

Wideband chaotic generation and optimization of characteristics in microwave generator with electronic feedback and magnetic periodic focusing system

With the help of 2D numerical model it has been investigated the nonlinear dynamics and generation of wideband chaotic signals in the generator based on electron beam with the virtual cathode. It has been discovered the strong influence of the external non­uniform magnetic field on the nonlinear dynamics of the virtual cathode in the system. It has been analyzed the physical processes responsible for the discovered dependency of dynamics of the electron beam with the virtual cathode on the parameters of the external non­uniform magnetic field.

Nonlinear dynamics of long mirrorless fiber raman laser

Numerical model of long fiber Raman laser is proposed. The model based on the equations, describing the propagation of pump and Stokes waves, linear coupling of oppositely running waves due to scattering and its nonlinear interaction. The derivation of equations for slowly varying pulse envelopes uses the field decomposition in terms of spatial harmonics rather then commonly used temporal harmonics, which allows to avoid the two­point boundary conditions, and to employ the numerical scheme of Courant–Isaakson–Rees.

On the mechanism of «compressed»­state formation at relativistic electron beam in two­section drift tube

This paper is devoted to the three­dimensional numerical simulation of the «compressed» state of the relativistic electron beam in two­section vircator system with drift tubes with different diameters. We have discovered the mechanism of formation of the «compressed» state of the relativistic beam through the formation of two virtual cathode near the anode grid and between connected sections, which will eventually merged into one distributed in the drift space virtual cathode (compressed state of the beam).

Numerical simulation of electron-beam «squeezed» state in purpose to study the possibility of effective plasma frequency increase

Three-dimensional electromagnetic numerical simulation is carried out of «squeezed» state of the electron beam in two-section vircator system with drift tubes of different diameters. We have studied the influence of two-section system geometric parameters on the nonlinear dynamics of electron beam. We have obtained an effective plasma frequency depending on the system parameters.