Dependence of the electric field on the specific surface conductivity of PbO2,, 3PbO · PbSO4 and 4PbO · PbSO4

1997 ◽  
Vol 64 (1-2) ◽  
pp. 61-64 ◽  
Author(s):  
N. Saidi ◽  
H. Saidi ◽  
B. Saidani ◽  
S.P. Stoylov
Keyword(s):  
Electric Field ◽  
Specific Surface ◽  
Surface Conductivity

SURFACE ELECTRICAL CONDUCTANCE AND ELECTROKINETIC POTENTIALS IN NETWORKS OF FIBROUS MATERIALS

1959 ◽  
Vol 37 (7) ◽  
pp. 1153-1164 ◽  
Author(s):  
C. E. Mossman ◽  
S. G. Mason
Keyword(s):  
Specific Surface ◽  
Double Layer ◽  
Electrical Double Layer ◽  
Electrolyte Concentration ◽  
Electrical Conductance ◽  
Surface Conductivity ◽  
Capillary Network ◽  
Fibrous Materials ◽  
Ζ Potential ◽  
Conductance Data

Stream-current, permeability, and conductance measurements were made on cylindrical pads of randomly oriented Dacron, glass, Nylon, and Orlon fibers over a range of electrolyte and solid concentrations. Values of the specific surface conductivity were computed from the conductance data, using equations which were derived from a capillary network theory.The measured conductance values were independent of pad concentration, increased with increasing electrolyte concentration, and were higher than values calculated from electrical double-layer theory using the measured values of ζ-potential. A number of plausible reasons for the discrepancies are advanced.

scholarly journals Influence of Surface-conductivity Nonuniformity on Charge Accumulation Phenomena of GIS Insulator under DC Electric Field

2011 ◽  
Vol 131 (7) ◽  
pp. 584-590 ◽  
Author(s):  
Taiki Donen ◽  
Hiroyuki Iwabuchi ◽  
Shigeyasu Matsuoka ◽  
Akiko Kumada ◽  
Kunihiko Hidaka ◽  
...  
Keyword(s):  
Electric Field ◽  
Surface Conductivity ◽  
Charge Accumulation ◽  
Dc Electric Field

Unsteady electrophoretic motion of a non-spherical colloidal particle in an oscillating electric field

1994 ◽  
Vol 278 ◽  
pp. 149-174 ◽  
Author(s):  
Michael Loewenberg
Keyword(s):  
Dielectric Constant ◽  
Electric Field ◽  
Colloidal Particle ◽  
Volume Fraction ◽  
Added Mass ◽  
Surface Conductivity ◽  
Spherical Particles ◽  
Oscillating Electric Field ◽  
Dilute Suspension ◽  
Spherical Colloidal Particle

The oscillatory motion of an electrically charged non-spherical colloidal particle in an oscillating electric field is investigated. The particle is immersed in an incompressible viscous fluid and assumed to have a thin electric double layer. For moderate-aspect-ration spheroids and cylinders, a simple algebraic expression is derived that accurately describes oscillatory electrophoretic particle motion in terms of the steady Stokes resistance, added mass, and Basset force. The effects of double-layer conduction and displacement currents within dielectric particles are included. The results indicate that electroacoustic measurements may be able to determine the ζ-potential, dielectric constant, surface conductivity (and microstructural information contained therein), size, density, volume fraction, and possibly shape of non-spherical particles in a dilute suspension. A simple formula is obtained for the high-frequency electrical conductivity of a dilute suspension of colloidal spheroids with arbitrary charge and dielectric constant; only the added mass and Basset force are required and the requisite parameters are given. The result is needed for electroacoustic measurements but it may also be independently useful for determining the dielectric constant, surface conductivity, volume fraction, and possibly the shape of non-spherical particles in a dilute suspension. Electroacoustic energy dissipation is described for a dilute colloidal suspension. It is shown that resistive electrical heating and viscous dissipation occur independently. Electrical and viscous dissipation coefficients that characterize the order volume fraction contributions of the suspended particles are calculated; the electrical dissipation coefficient is O(1) for all oscillation frequencies, whereas the latter vanishes at low- and high-frequencies. The fluid motion is shown to be a superposition of unsteady, viscous and potential flows past an oscillating particle with no applied electric field. The electro-osmotic flow field is insensitive to particle geometry and qualitatively different from the flow past an oscillating particle with no applied field.

scholarly journals The role of surface conductivity in electromechanics and electrohydrodynamics of a dielectric drop

2018 ◽  
pp. 110-117
Author(s):  
V. Datsyuk ◽  
O. Pavlyniuk
Keyword(s):  
Electric Field ◽  
Silicone Oil ◽  
Ambient Medium ◽  
New Technology ◽  
Surface Conductivity ◽  
Back Surface ◽  
Surface Conductance ◽  
Field Frequency ◽  
Low Frequencies ◽  
Weakly Conducting

A new technology of the electric-field manipulation by dielectric particles in dielectric liquids and drops has been developed in the last decades. To simulate electromechanics of microparticles in a weaklyconducting dielectric drop the Taylor's leaky-dielectric model is extended. To achieve this electric-potential distribution inside and outside a weakly-conducting dielectric sphere embedded in a weakly-conducting dielectric in an electric field is determined taking into account the interfacial current. The conventional definition of the total, bulk plus surface, conductance of the sphere is detailed allowing for its dependence on the angular distribution of the external electric field. Technology of microparticles moving over the interface of the drop is based on the application of electrohydrodynamic (EHD) drag and dielectrophoretic (DEP) forces. The surface conductivities of the drop and individual microparticles can have a significant influence on the surface charge and thereby on the DEP and EHD drag forces. Thus, we show that recent explanation of manipulation by microparticles trapped at the interface of a silicone-oil drop immersed in castor oil is misleading. Taking into account the surface conductivity of the microparticles, we find that EHD drag and DEP forces are of the same direction but not opposite at zero or low frequencies as stated previously. Due to the reversal of the DEP force with the field frequency the motion of microparticles turns back. Surface conductivity of the drop can also explain experiments in which the prolate deformation persists after liquids of the drop and ambient medium are interchanged.

Resolution in photoelectron microscopy

1991 ◽  
Vol 49 ◽  
pp. 458-459
Author(s):  
G. F. Rempfer
Keyword(s):  
Electron Microscopy ◽  
Electric Field ◽  
Ultraviolet Light ◽  
Uniform Field ◽  
Virtual Image ◽  
Lens System ◽  
Photoemission Electron Microscopy ◽  
Planar Electrode ◽  
Electron Lens ◽  
Photoemission Electron

In photoelectron microscopy (PEM), also called photoemission electron microscopy (PEEM), the image is formed by electrons which have been liberated from the specimen by ultraviolet light. The electrons are accelerated by an electric field before being imaged by an electron lens system. The specimen is supported on a planar electrode (or the electrode itself may be the specimen), and the accelerating field is applied between the specimen, which serves as the cathode, and an anode. The accelerating field is essentially uniform except for microfields near the surface of the specimen and a diverging field near the anode aperture. The uniform field forms a virtual image of the specimen (virtual specimen) at unit lateral magnification, approximately twice as far from the anode as is the specimen. The diverging field at the anode aperture in turn forms a virtual image of the virtual specimen at magnification 2/3, at a distance from the anode of 4/3 the specimen distance. This demagnified virtual image is the object for the objective stage of the lens system.

Field-assisted ionization theory for microscopists

1994 ◽  
Vol 52 ◽  
pp. 820-821
Author(s):  
Patrick P. Camus
Keyword(s):  
Electric Field ◽  
Electron Tunneling ◽  
Ionization Probability ◽  
Critical Distance ◽  
Tunneling Probability ◽  
Field Ionization ◽  
Radius Of Curvature ◽  
Field Evaporation ◽  
A Value ◽  
Ion Emission

The theory of field ion emission is the study of electron tunneling probability enhanced by the application of a high electric field. At subnanometer distances and kilovolt potentials, the probability of tunneling of electrons increases markedly. Field ionization of gas atoms produce atomic resolution images of the surface of the specimen, while field evaporation of surface atoms sections the specimen. Details of emission theory may be found in monographs.Field ionization (FI) is the phenomena whereby an electric field assists in the ionization of gas atoms via tunneling. The tunneling probability is a maximum at a critical distance above the surface,xc, Fig. 1. Energy is required to ionize the gas atom at xc, I, but at a value reduced by the appliedelectric field, xcFe, while energy is recovered by placing the electron in the specimen, φ. The highest ionization probability occurs for those regions on the specimen that have the highest local electric field. Those atoms which protrude from the average surfacehave the smallest radius of curvature, the highest field and therefore produce the highest ionizationprobability and brightest spots on the imaging screen, Fig. 2. This technique is called field ion microscopy (FIM).

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