scholarly journals POTENTIAL, ELECTRIC FIELD AND SURFACE CHARGES CLOSE TO THE BATTERY FOR A RESISTIVE CYLINDRICAL SHELL CARRYING A STEADY LONGITUDINAL CURRENT

2004 ◽  
Vol 12 (2) ◽  
Author(s):  
J. A. Hernandes ◽  
E. Capelas de Oliveira ◽  
A. K. T Assis
Keyword(s):  
Cylindrical Shell ◽  
Electric Field ◽  
Surface Charges ◽  
Longitudinal Current

Electric-Field Induced Formation of Superconducting Granular Balls

2002 ◽  
Vol 16 (17n18) ◽  
pp. 2529-2535
Author(s):  
R. Tao ◽  
X. Xu ◽  
Y. C. Lan
Keyword(s):  
Surface Energy ◽  
Electric Field ◽  
Liquid Nitrogen ◽  
Applied Electric Field ◽  
Strong Electric Field ◽  
Particle Surface ◽  
Cooper Pairs ◽  
Surface Charges

When a strong electric field is applied to a suspension of micron-sized high T c superconducting particles in liquid nitrogen, the particles quickly aggregate together to form millimeter-size balls. The balls are sturdy, surviving constant heavy collisions with the electrodes, while they hold over 106 particles each. The phenomenon is a result of interaction between Cooper pairs and the strong electric field. The strong electric field induces surface charges on the particle surface. When the applied electric field is strong enough, Cooper pairs near the surface are depleted, leading to a positive surface energy. The minimization of this surface energy leads to the aggregation of particles to form balls.

Electrohydrodynamic Kelvin-Helmholtz Instability of Two Rotating Dielectric Fluids

1998 ◽  
Vol 53 (1-2) ◽  
pp. 17-26
Author(s):  
Mohamed Fahmy El-Sayed
Keyword(s):  
Electric Field ◽  
Electric Fields ◽  
Applied Electric Field ◽  
Rotation Frequency ◽  
Short Wave ◽  
Surface Charges ◽  
Rotation Surface ◽  
Dielectric Fluids ◽  
Fluid Velocities ◽  
Conditions Of Stability

Abstract A linear stability analysis of a novel electrohydrodynamic Kelvin-Helmholtz system consisting of the superposition of two uniformly rotating dielectric media is presented. The characteristic equation for such an arrangement is derived, which in turn yields a stability criterion for velocity differences of disturbances at a given rotation frequency. The conditions of stability for long and short wave perturbations are obtained, and their dependence on rotation, surface tension and applied electric field is discussed. Limiting cases for vanishing fluid velocities, rotation frequency, and applied electric field are also discussed. Under suitable limits, results of previous works are recovered. A detailed analysis for tangential and normal applied electric fields, in the presence and absence of surface charges, is carried out.

A calculation of the surface charges and the electric field outside steady current carrying conductors

1996 ◽  
Vol 17 (1) ◽  
pp. 37-42 ◽  
Author(s):  
N Sarlis ◽  
G Kalkanis ◽  
C A Londos ◽  
S S Sklavounos ◽  
P Tsakonas
Keyword(s):  
Electric Field ◽  
Surface Charges ◽  
Steady Current

scholarly journals Parameters characterizing the charge state of dielectrics

2017 ◽  
Vol 35 (3) ◽  
pp. 601-605 ◽  
Author(s):  
Bożena Łowkis
Keyword(s):  
Free Surface ◽  
Electric Field ◽  
Charge State ◽  
Free Volume ◽  
Infinite Number ◽  
Polarization State ◽  
Surface Charges ◽  
Volume Conductivity ◽  
Total Lifetime ◽  
Relaxation Decay

AbstractThis paper presents three physical sources of the electric field in dielectrics: excess free volume charges with the distribution qv(x,y,z), free surface charges with the distribution qs(x,y,z) and frozen polarization state in the dielectric. They have a deciding influence on the parameters of the electret, in particular they determine the total lifetime of the electret and technical components made of it. The indeterminacy related to the mutual proportions of the spatial and surface charges was discussed: one can find an infinite number of distributions of surface qse(x,y,z) and spatial qve(x,y,z) charges leading to the same distribution of the electric field E(x,y,z). A general case of electret was considered, where a coexistence of relaxation decay of frozen polarization and Maxwellian relaxation dependent on volume conductivity of the dielectric is assumed. An attempt to interpret the charge lifetime in real electrets was made.

scholarly journals Electromagnetic Casimir densities for a cylindrical shell on de Sitter space

2016 ◽  
Vol 31 (34) ◽  
pp. 1650183 ◽  
Author(s):  
A. A. Saharian ◽  
V. F. Manukyan ◽  
N. A. Saharyan
Keyword(s):  
Cylindrical Shell ◽  
Electric Field ◽  
Energy Momentum Tensor ◽  
Vacuum Expectation ◽  
Vacuum State ◽  
Momentum Tensor ◽  
Curvature Radius ◽  
Perfect Conductor ◽  
De Sitter ◽  
Proper Distance

Complete set of cylindrical modes is constructed for the electromagnetic field inside and outside a cylindrical shell in the background of [Formula: see text]-dimensional dS space–time. On the shell, the field obeys the generalized perfect conductor boundary condition. For the Bunch–Davies vacuum state, we evaluate the vacuum expectation values (VEVs) of the electric field squared and of the energy–momentum tensor. The shell-induced contributions are explicitly extracted. In this way, for points away from the shell, the renormalization is reduced to the one for the VEVs in the boundary-free dS bulk. As a special case, the VEVs are obtained for a cylindrical shell in the [Formula: see text]-dimensional Minkowski bulk. We show that the shell-induced contribution in the electric field squared is positive for both the interior and exterior regions. The corresponding Casimir–Polder forces are directed toward the shell. The vacuum energy–momentum tensor, in addition to the diagonal components, has a nonzero off-diagonal component corresponding to the energy flux along the direction normal to the shell. This flux is directed from the shell in both the exterior and interior regions. For points near the shell, the leading terms in the asymptotic expansions for the electric field squared and diagonal components of the energy–momentum tensor are obtained from the corresponding expressions in the Minkowski bulk replacing the distance from the shell by the proper distance in the dS bulk. The influence of the gravitational field on the local characteristics of the vacuum is essential at distances from the shell larger than the dS curvature radius. The results are extended for confining boundary conditions of flux tube models in QCD.

Electrospun Nafion Nanofiber for Proton Exchange Membrane Fuel Cell Application

2009 ◽  
Vol 6 (3) ◽  
Author(s):  
R. Bajon ◽  
S. Balaji ◽  
S. M. Guo
Keyword(s):  
Electric Field ◽  
Porous Structure ◽  
Active Sites ◽  
Proton Exchange Membrane ◽  
Gas Diffusion ◽  
Proton Exchange ◽  
Membrane Electrode ◽  
Surface Charges ◽  
Power Sources ◽  
Exchange Membrane

Proton exchange membrane fuel cells (PEMFCs) are attractive power plants for use in many applications, including portable power sources, electric vehicles, and on-site combined power/heat plants, due to the inherently high efficiency and low emission. The membrane electrode assembly (MEA) is the key component of a PEMFC. A standard five layer MEA consists of a proton exchange membrane, two catalyst layers, and two gas diffusion layers. The most commonly used electrolyte material is proton conductive perfluorinated sulfonic acid membrane, such as Nafion. Hydrogen is oxidized at the anode/electrolyte interface, the so-called triple-phase-boundary (TPB) active sites. TPB region must be a good electron conductor, a good ion conductor, and a porous structure for fuel/air diffusion. Typical PEMFC TPB is a porous structure made with Nafion and catalyst particle mixture. In this paper, electrospinning is used to synthesize polymer/Nafion nanofibers. Electrospinning is a straightforward method that has been successfully used to prepare fibers or fiber mats from a broad range of organic polymers. In the electrospinning process, a polymer solution held by its surface tension at the end of a capillary tube is subjected to an electric field, and as the electric field strength increases, a solid fiber is generated as the electrified jet is continuously stretched because of the electrostatic repulsions between the surface charges and the evaporation of solvent. Uniform one-dimensional Nafion nanofibers have been fabricated using Nafion solution and solutions containing polyvinyl pyrrolidone, polyethylene oxide, and polyvinyl alcohol. The morphologies of polymer/Nafion nanofibers, fabricated under different electrospinning conditions and different polymer compositions, are presented.

Nonlinear Electrohydrodynamic Stability of Two Superposed Bounded Fluids in the Presence of Interfacial Surface Charges

1998 ◽  
Vol 53 (5) ◽  
pp. 217-232 ◽  
Author(s):  
M. F. El-Sayed ◽  
D. K. Callebaut
Keyword(s):  
Schrödinger Equation ◽  
Electric Field ◽  
Nonlinear Schrödinger Equation ◽  
Schrodinger Equation ◽  
Nonlinear Schrodinger Equation ◽  
Surface Charges ◽  
Nonlinear Schrödinger ◽  
Interfacial Surface ◽  
Lower Fluid ◽  
The One

Abstract The method of multiple scales is used to analyse the nonlinear propagation of waves on the interface between two superposed dielectric fluids with uniform depths in the presence of a normal electric field, taking into account the interfacial surface charges. The evolution of the amplitude for travelling waves is governed by a nonlinear Schrödinger equation which gives the criterion for modulational instability. Numerical results are given in graphical form, and some limiting cases are recovered. Three cases, in the pure hydrodynamical case, depending on whether the depth of the lower fluid is equal to or greater than or smaller than the one of the upper fluid are considered, and the effect of the electric field on the stability regions is determined. It is found that the effect of the electric field is the same in all the cases for small values of the field, and there is a value of the electric field after which the effect differs from case to case. It is also found that the effect of the electric field is stronger in the case where the depth of the lower fluid is larger than the one of the upper fluid. On the other hand, the evolution of the am-plitude for standing waves near the cut-off wavenumber is governed by another type of nonlinear Schrödinger equation with the roles of time and space are interchanged. This equation makes it possible to determine the nonlinear dispersion relation, and the nonlinear effect on the cut-off wavenumber.

scholarly journals Numerical Modeling of Space–Time Characteristics of Plasma Initialization in a Secondary Arc

Energies ◽  
2019 ◽  
Vol 12 (11) ◽  
pp. 2128
Author(s):  
Jinsong Li ◽  
Hua Yu ◽  
Min Jiang ◽  
Hong Liu ◽  
Guanliang Li
Keyword(s):  
Numerical Model ◽  
Electric Field ◽  
Single Phase ◽  
Short Circuit ◽  
Negative Ions ◽  
Ion Source ◽  
Simulation Software ◽  
Discharge Process ◽  
Field Variation ◽  
Surface Charges

A numerical model based on the finite element simulation software COMSOL was developed to investigate the secondary arc that can limit the success of single-phase auto-reclosure solutions to the single-phase-to-ground fault. Partial differential equations accounting for variation of densities of charge particles (electrons, positive and negative ions) were coupled with Poisson’s equation to consider the effects of space and surface charges on the electric field. An experiment platform was established to verify the numerical model. The brightness distribution of the experimental short-circuit arc was basically consistent with the predicted distribution of electron density, demonstrating that the simulation was effective. Furthermore, the model was used to assess the particle density distribution, electric field variation, and time dependence of ion reactions during the short-circuit discharge. Results showed that the ion concentration was higher than the initial level after the short-circuit discharge, which is an important reason for inducing the subsequent secondary arc. The intensity of the spatial electric field was obviously affected by the high-voltage electrode at the end regions, and the intermediate region was mainly affected by the particle reaction. The time correspondence between the detachment reaction and the ion source generated in the short-circuit discharge process was basically consistent, and the detachment reactions were mainly concentrated in the middle area and near the negative electrode. The research elucidates the relevant plasma process of the secondary arc and will contribute to the suppression of it.

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