Vasily Yu. Kozhevnikov

Theoretical Simulation of a Gas Breakdown Initiated by External Plasma Source in the Gap With Combined Metal–Dielectric Electrodes

This paper is devoted to the theoretical investigation of the breakdown in short discharge gaps of different geometries under the influence of the plasma stream from an external source. The structural feature is the presence of dielectric elements in the electric discharge gap area, which have high emission activity and the ability to accumulate a surface charge. The simulation was performed for a 2-D planar geometry of the discharge gap between two metal electrodes with dielectric coating surrounded by the gaseous medium. Charged particles generation and dynamics have been described by a system of partial differential equations in the diffusion-drift approximation within the two-fluid hydrodynamics plasma model. The basic advantages of the proposed model (such as a wide variety of boundary conditions and geometries of the discharge gap, the scalability of the critical parameters of the environment, and a simple representation of surface reactions) are demonstrated successfully. During computations, the range of gas pressure and the external preionization level at which the probability of low-voltage self-sustained discharge is high enough were identified.

Design and diagnostics of arc-resistant electronics for satellite telecommunication systems

This paper proposes a modern theoretical approach for the complex diagnostics of on-board electronic equipment for the occurrence of primary electric arcing in satellite telecommunication systems. Our method is based on the gradual partitioning of an electronic device into regions that are potentially vulnerable to primary arcing. We solve the complete plasma physics problem with a parametric sweep for each vulnerable region as an independent computational plasma physics problem to obtain the critical parameter diagrams. Each diagram shows the most and least dangerous ranges of critical parameters with respect to the possibility of arcing in a spacecrafts operating conditions. A large set of two-/three-dimensional critical parameter diagrams is widely used for the complex diagnostics and development of electronic systems that are arc-resistance under various operating conditions.

Zero-Dimensional Theoretical Model of Subnanosecond High-Pressure Gas Discharge

This paper deals with the results of the breakdown process simulation in strongly overvoltage gaps under high pressures. The presented 0-D model of discharge enables the estimation of characteristic parameters of the initial stage of the breakdown: current rise rate, time of voltage decay across the gap, and current pulse duration of runaway electrons. The discharge model takes into account 0-D growth kinetics of the plasma density in the gap and the impact of the external power supply circuit of the discharge, including the interelectrode capacitance. The model enables estimation of the number and energy range of runaway electrons generated at the initial stage of high-pressure gas breakdown. As an example, computations were conducted for discharge in nitrogen. A comparison of the simulation results with the experimental data enables estimation of the level of the critical field in which we can expect the generation of runaway electrons in the gas discharge.

Diagnostics of primary arcing in electronics of satellite telecommunication systems

In this paper we propose a modern theoretical approach for complex diagnostics of onboard electronic equipment for the occurrence of primary electric arcing in satellite telecommunication systems. Our method based on the gradual partitioning of the electronic device into regions potentially vulnerable to primary arcing. We solve complete plasma physics problem with parametric sweep for each vulnerable region as an independent computational plasma physics problem in order to obtain the critical parameters diagram. It shows most dangerous and least dangerous ranges of critical parameters with respect to the possibility of arcing in spacecraft operating conditions. A large set of two- and three-dimensional critical parameters diagram is widely used for complex diagnostics and development of arc-resistant electronic systems.

Simulation and optimization of dummy loads for microwave calorimeters

A two-dimensional finite-difference time-domain method with uniaxial perfectly matched layers was applied to analysis of a three-layer wide-aperture microwave calorimeter. The method was shown to be an efficient tool for calculating the optimum geometric parameters of a semi-infinite model dummy load. Using the time-domain results, the frequency-dependent transmission/reflection coefficients of the load were calculated for normal incidence of a monochromatic plane wave at operating frequencies range of 1-12 GHz for the first time.

Phase stabilization effect in nanosecond microwave Gunn oscillators

The paper studies the influence of semiconductor structure on microwave oscillation phase stabilization in a nanosecond Gunn oscillator during the modulating voltage pulse rise time. The phase deviation depending on the pulse amplitude and rise time was determined by numerical simulation. The standard deviation of the microwave oscillation phase delay about a fixed level within the modulating pulse rise time and the standard deviation of the microwave oscillation phase difference in two electrodynamically decoupled oscillators were measured.

Modeling of Space Charge Effects in Intense Electron Beams: Kinetic Equation Method Versus PIC Method

In this paper, we present the simulation results for the most important 1-D problems of current flow in planar vacuum diodes. For the first time, classical problems of vacuum electronics have been solved using the basic principles of nonequilibrium physical kinetics. This approach is based on the accurate numerical solution of the Vlasov–Poisson equation system to find the electron distribution function. We have obtained time-dependent numerical solutions that satisfactorily agree with theoretical approximations and with particle-in-cell simulations as well.

Kinetic modelling of the one-dimensional planar virtual cathode oscillator

Our paper presents the simulation results for the one-dimensional virtual cathode oscillator problem solved in terms of computational physical kinetics. Current classical problem of the electron beam injection into vacuum equipotential gap has been solved for the first time using the approach based on accurate numerical solution of Vlasov-Poisson system. We also provide the comparison of obtained results with particle-in-cell simulation and approximate analytical assessments.

Coherent radiation summation of two X-band nanosecond Gunn oscillators synchronized by a modulating pulse

In the paper, we compare total wave fields in the X-band for two reference coherent microwave sources and for two nanosecond Gunn oscillators with initial phase stabilization by a common modulating voltage pulse. It is shown that the wave fields agree well.

Hybrid model of runaway electrons generation process in nanosecond high pressure gas discharge

Summary form only given. The paper deals with the results of theoretical modeling of runaway electrons generation which occurs in the high-pressure nanosecond pulsed gas breakdown. For these purposes a novel hybrid model of the gas discharge has been successfully built. It uses hydrodynamic and kinetic approaches simultaneously to describe the dynamics of different components of low-temperature discharge plasma. Namely, it uses corresponding equations of continuity with drift-diffusion approximation to consider motion of ions and low-energy (Maxwellian) electrons. On the other hand the description of high-energy (runaway) electrons is implemented by including the Boltzmann kinetic equation. Also this system is completed by Maxwell equations set to take into the account the agreed electric field distribution.Numerical solution of equations system allows to describe in details spatial and temporal structure of the plasma, the electric field distribution, as well as the quantity and energy spectrum of runaway electrons that are generated at highvoltage breakdown stage of nanosecond discharge. In contrast to the numerical methods operating with restricted ensemble of particles (i.e. Monte Carlo methods, PIC methods, etc.), the proposed approach allows to calculate the spectrum of a statistically small amount of fast electrons. In particular, it was shown that spectrum of fast electrons at anode depends on the peculiarities of the plasma density and electric field distributions at non-stationary stage of the gas breakdown.