Exisymmetrical excitation of an ideally conducting body of revolution covered with a thin layer of dielectric

Conclusions An approximate integral equation of the first kind has been obtained for the problem of the excitation of a body of revolution with a thin layer of dielectric. The equation is written with respect to the surface charge density. The thickness of the layer and its dielectric permittivity can vary along the generatrix of the body of revolution.Numerical results of calculations for a sphere are given for evaluation of the exactness of the solution of the integral equation and are of a methodological character. The method of solution proposed and the algorithm developed make it possible to consider the problem of the excitation of bodies of revlution with an arbitrary form of the generatrix, covered by a layer of dielectric. This method has been used to solve the problem of the excitation of a metallic cone and several other bodies covered with a thin layer of dielectric.Moscow Power Institute. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 21, No. 10, pp. 1505–1512, October, 1978.     

Dynamics of the free surface of a conducting liquid in a near-critical electric field

Near-critical behavior of the free surface of a perfectly conducting liquid in an external electric field is considered. Based on an analysis of three-wave processes using the method of integral estimates, sufficient criteria for hard instability of a planar surface are formulated. It is shown that the higher-order nonlinearities do not saturate the instability, for which reason the growth of disturbances has an explosive character.     

Electrostatic charging of a conducting sphere using another conducting sphere at constant voltage

This study uses results of classical electrostatics to predict the resulting voltage of a conducting sphere that is charged by a second sphere maintained at a constant voltage. The voltage of the charged sphere is calculated as a function of the charging voltage and the size ratio of the two spheres. Theoretical predictions are verified experimentally using conducting spheres of various sizes and a Faraday ice pail apparatus. The results may seem somewhat counterintuitive. For example, a charging sphere held at 100 V will charge another sphere of equal size only to 69.3 V by contact.     

Observation of depression solitary surface waves on a thin fluid layer

We report the observation of depression solitary surface waves on a layer of mercury when its depth is thin enough compared to the capillary length. These waves, as well as the well known elevation solitary waves, are studied with a new measurement technique using inductive sensors. The shape of the solitary waves, their amplitude-dependent velocity, and their damping rates by viscosity are found in good agreement with theoretical predictions.     

Influence of a magnetically permeable surface layer on transient fields for a thin circular loop antenna

The transient fields, in the time-domain, of a thin circular loop antenna, on a two-layered earth’s model are reexamined when the usually neglected magnetic permeability contrast is considered. It is shown that for a two-layered earth model, where the upper layer is permeable, the transient fields are modified over the nonpermeable case. The fields in the time domain are obtained as the inverse Laplace transforms of derived full wave time-harmonic solution. These time-domain solutions are obtained as a summation of waveguide modes plus contributions from branch cuts in the complex plane of the longitudinal wave number. The results should be useful for interpreting airborne electromagnetic systems and in cases where super-paramagnetic mineral constant is present.     

Transition radiation emitted by a particle moving along the axis of a perfectly conducting conical surface

The spatial field distribution is determined for the transition radiation emitted by a relativistic particle moving along the axis of a perfectly conducting circular conical surface with a fixed apex. Emission from particles moving away from and towards the apex is examined. Expressions are obtained that can be used to calculate the angular distribution of radiation intensity for various apex angles between 0 and π. Significant differences are demonstrated between the spatial distributions of radiation generated by outgoing and incoming particles.     

On the possibility of initiating a corona discharge at the crests of nonlinear waves on the surface of a charged thin layer of a viscous conducting liquid

An analytic expression for the electrostatic field strength at the free surface of a thin layer of a uniformly charged viscous incompressible liquid is obtained in second-order asymptotic calculations in the amplitude of a periodic capillary-gravity wave propagating over the liquid surface. It is shown that a corona discharge at the crests of the waves can be initiated at subcritical values of the field strength (in the sense of possible realization of the Tonks-Frenkel instability). The electrostatic field strength at the crests of nonlinear waves increases with the wavenumber and the wave amplitude.     

Effect of surface conduction on the dynamics of induction charging of particles

The purpose of this paper is to investigate the dynamics of induction charging for spherical particles assuming finite volume and surface conductivities. It is assumed that the thickness of the surface layer is a small percentage of the particle radius. All results were obtained using COMSOL commercial software. The results show that the rate of charge accumulation is affected by the conductivity, permittivity and the contact area with the ground electrode. It is shown that the actual charging time constant for a material with fixed bulk properties can differ considerably from the relaxation time.     

Influence of a thin surface layer on light scattering by spherical particles

The Mie problem with modified boundary conditions that take into account the influence of a thin surface layer on the scattering of an electromagnetic wave by a spherical particle is considered. Analytical equations are derived for the partial amplitudes of scattered waves and forced oscillations. These equations are applicable in the case of anisotropy and gyrotropy of an optical response from the surface layer.     

Nonlinear oscillations of a charged layer of a conducting liquid on the surface of a solid spherical core

Nonlinear oscillations of a layer of an ideal incompressible perfectly conducting liquid on the surface of a charged melting hailstone (solid core) are studied using analytical asymptotic calculations of the second order of smallness in initial deformation amplitude. Specifically, it is shown that, when the thickness of the layer is much less than the characteristic linear size (radius) of the solid core, the size of the core considerably influences the amplitudes of capillary oscillation modes arising on the surface of the charged layer via nonlinear interaction. It is found that, as the liquid layer on the surface of the solid core gets thinner, the energy in the spectrum of nonlinearly excited modes is redistributed with its maximum shifting toward higher (larger number) modes.     

Dynamics of self-organization in a thin layer of a magnetic fluid placed in a constant electric field

Structuring in the form of rotating rings, which has not been observed previously in magnetic fluids, is revealed, and the parameters of these structures are determined. Also, the evolution of vortices in a magnetic fluid layer is traced. The electrical properties of the layer exposed to a constant electric field are studied as functions of the field magnitude and exposure time.     

Voltage self-sustained oscillation and phase separation dynamics in a thin layer of a weakly conducting ferromagnetic liquid with periodically emerging electrohydrodynamic flows

It is shown that voltage self-sustained oscillations, which are determined by the properties of the near-electrode layer and electrohydrodynamic flows that are periodically formed in the colloid layer, emerge for a preset direct current at the electrodes of a plane-parallel cell filled with a colloid system consisting of stabilized magnetic nanoparticles dispersed in a weakly conducting liquid. The effect of self-sustained oscillations and periodic electrohydrodynamic flows in phase separation in the colloid system is analyzed. It is found that new dynamic formations are generated, which are regions of elevated concentration of magnetite particles having the shape of labyrinths of millimeter size. The emergence of a negative real part of the permittivity of the colloid layer is detected and attributed to the fact that the normal component of the internal electric field produced by volume charges becomes codirectional with the applied field when steady-state electrohydrodynamic flows appear in the system.     

Polarization spectroscopy of a conducting surface

A method of polarization spectroscopy for a conducting surface characterized by a high sensitivity to the state of the surface and its transition layer is proposed. The method uses excitation of surface electromagnetic waves (SEWs) by a linearly polarized probe beam incident on the surface under study and compensation for the phase shift between the p and s components arising upon the SEW excitation. The applicability and competitiveness of the method in both the visible and the IR range is established. The method is tested on an LEF-3M ellipsometer in the visible range by studying the oxidation process in an evaporated copper film.     

板底薄层的超声谐振检测分析

理论上研究了带有薄层的板的超声谐振频率随薄层的厚度或物性改变而发生变化的规律,研究结果表明,在0 ≤ ω<c₂/d₂ arctan (Z₁/Z₂)范围内,板的半波谐振频率因薄层厚度的增加向低频飘移;在一阶近似条件下,飘移量的大小正比于薄层和板的单位面积质量之比。在此基础上,提出了利用板的谐振频率飘移量进行板底薄层厚度检测的方法,并对6.24 mm厚铝板下不同厚度(54-324 μm)的薄层进行了厚度检测,实验得到的厚度相对误差在6%以下。实验结果进一步证实了该规律是正确的,以及基于该规律的板底薄层检测方法是可行的。     

Electromagnetic mass correction for a charged particle due to conducting boundaries

The mass correction of a charged scalar particle is calculated in terms of the energy shift of the ground state in a constant magnetic field localized between ideally conducting plates.     

Screening of a charged dust particle within a nonlocal charging theory

We study the influence of the nonlocality of the electron energy distribution function on the dust particle charge screening in a two-component plasma of various inert gases and nitrogen at atmospheric pressure. For our analytical and numerical calculations, we have chosen the point sink model in the diffusion-drift approximation, which, in addition to the bulk production and loss of electrons and ions, also includes the heterogeneous processes of their absorption by a dust particle. We have established that the dust particle potential distribution in the problem under consideration is a superposition of three Debye exponentials with three different screening constants. The first constant practically coincides with the inverse Debye length. The second constant is determined by the inverse length travelled by the electrons and ions in the ambipolar diffusion process in the characteristic recombination time. The third constant coincides with the inverse characteristic distance of electron energy transfer through heat conduction in the characteristic time of electron energy establishment in the processes of heating by a beam of fast electrons and energy losses in elastic and inelastic collisions. We compare our numerical calculations of the screening constants with the analytical estimates obtained in the ambipolar diffusion approximation.     

粗糙面上粒子层矢量辐射传输方程的二阶迭代解法

为了探究典型粗糙面上随机粒子层中能量传输的多次散射机制,提出了一种基于矢量辐射传输方程的建模二阶计算方法.该建模方法将建模场景(粗糙面上粒子层)在高度维(Z轴)划分为多个传输散射层,基于矢量辐射传输理论中的一阶迭代散射解,利用典型粗糙面的半经验半解析方法,求解出整个场景的二阶迭代散射解.同时,研究粒子层能量在粒子与粒子间的多次散射机制,以及粒子与地表粗糙面间的多次散射机制.数值结果表明,该二阶迭代解法相较于矢量辐射传输方程的一阶迭代散射解,能够更完整地探究互作用的散射特性,且可从能量传输角度解译建模场景中物体间的相干作用,从而可用于植被地物环境下的多次散射机制的解析以及散射系数变化趋势的预估.     

On the new procedure for the determination of surface conditions in thin films with internal layer inhomogeneity

A method for determining the surface conditions on both surfaces of the film, based in the thickness dependence of localized states is proposed.