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Showing papers on "Electric potential published in 1980"


Journal ArticleDOI
TL;DR: In this paper, the authors proposed a new theoretical model for the light-induced migration of charges which mediates the photorefractive effect in barium titanate and other crystals, and the theoretical model predicts the observed dependences of these effects on (1) beam intensities, directions and polarizations, (2) crystal orientation, and (3) on an externally applied dc electric field.
Abstract: We propose a new theoretical model for the light‐induced migration of charges which mediates the ’’photorefractive effect’’ (light‐induced refractive index change) in barium titanate and other crystals. We also present experimental results of various effects of this light‐induced charge migration in a single‐domain crystal of barium titanate, specifically, (1) energy transfer between two intersecting optical beams, (2) optical four‐wave mixing and optical‐beam phase conjugation, (3) erasure of spatial patterns of photorefractive index variations, and (4) photoconductivity. The theoretical model predicts the observed dependences of these effects on (1) beam intensities, directions, and polarizations, (2) crystal orientation, and (3) on an externally applied dc electric field. Time dependences of transients as well as steady‐state magnitudes are predicted. In this model, identical charges migrate by hopping between adjacent sites, with a hopping rate proportional to the total light intensity at the starting site. The net hopping rate varies with the local electric potential that is calculated self‐consistently from the charge migration pattern. In barium titanate the charges are positive with a density of (1.90.2) ×1016 cm−3 at 514 nm. The origin of the charges and sites is at present unknown. The hopping rate constant determined from optical beam interactions is used to predict the observed photoconductivity of 1.3×10−10 cm Ω−1 W−1 at 514 nm.

426 citations


Journal ArticleDOI
TL;DR: In this article, it was shown that discontinuities in the magnetospheric convection electric field E with ▽ · E < 0 can generate large-scale regions (of the order of 100 km in width) of magnetic fieldaligned currents with associated field-aligned electric potential differences and electron precipitation.
Abstract: It is shown that discontinuities in the magnetospheric convection electric field E with ▽ · E <0 can generate large-scale regions (of the order of 100 km in width) of magnetic field-aligned currents with associated field-aligned electric potential differences and electron precipitation of the magnitudes and widths observed in auroral regions. Such an electric field discontinuity is known to exist along the evening boundary between sunward and antisunward convection. In addition, such discontinuities may also exist over the polar cap, on account of inhomogeneities in the magnetosheath flow and in regions, such as the Alfven layer, where drifting trapped particles charge separate. The present analysis assumes that the field-aligned current is governed by the free particle motion in dc electric and magnetic fields, and nothing is assumed to inhibit this free particle motion.

381 citations


Journal ArticleDOI
TL;DR: In this article, a collisionless plasma with arbitrary ion temperature in plane geometry is formulated and the plasma-sheath equation is solved numerically with no approximation of the Debye length.
Abstract: The plasma‐sheath equation for a collisionless plasma with arbitrary ion temperature in plane geometry is formulated. Outside the sheath, this equation is approximated by the plasma equation, for which an analytic solution for the electrostatic potential is obtained. In addition, the ion distribution function, the wall potential, and the ion energy and particle flux into the sheath are explicitly calculated. The plasma‐sheath equation is also solved numerically with no approximation of the Debye length. The numerical results compare well with the analytical results when the Debye length is small.

339 citations


Book
01 Jan 1980
TL;DR: The first and second laws of thermodynamics electric charge and electric field electric potential and electric energy electric currents DC circuits, electromagnetic induction and Faraday's Law - AC circuits electromagnetic waves light - geometric optics the wave nature of light optical instruments special theory of relativity early quantum theory and models of the atom quantum mechanics of atoms molecules and solids nuclear physics and radioactivity nuclear energy effects and uses of radiation elementary particles astrophysics and cosmology.
Abstract: Describing motion - kinematics in one dimension kinematics in two or three dimensions - vectors motion and force - dynamics circular motion - gravitation work and energy linear momentum rotational motion bodies in equilibrium - elasticity and fracture fluids vibrations and waves sound temperature and kinetic theory heat the first and second laws of thermodynamics electric charge and electric field electric potential and electric energy electric currents DC circuits, electromagnetic induction and Faraday's Law - AC circuits electromagnetic waves light - geometric optics the wave nature of light optical instruments special theory of relativity early quantum theory and models of the atom quantum mechanics of atoms molecules and solids nuclear physics and radioactivity nuclear energy effects and uses of radiation elementary particles astrophysics and cosmology. Appendices.

292 citations


Journal ArticleDOI
TL;DR: In this paper, a kinetic theory is used to model the field-aligned distribution of auroral electrons along dipole magnetic field lines, and analytical formulae are obtained for the particle flux (J/sub parallel/) and energy flux (epsilon) as functions of V, the electric potential difference between the equatorial source region and the ionosphere where the accelerated electrons are precipitated and detected by rocket instrumentation.
Abstract: A kinetic theory is used to model the field-aligned distribution of auroral electrons along dipole magnetic field lines. Analytical formulae are obtained for the particle flux (J/sub parallel/) and energy flux (epsilon) as functions of V, the electric potential difference between the equatorial source region and the ionosphere where the accelerated electrons are precipitated and detected by rocket instrumentation. For 1very-much-less-thaneV/E/sub 0parallel/very-much-less-than500, epsilon is nearly proportional to V/sup 2/, and J/sub parallel/ is proportional to V (E/sub 0parallel/ is the parallel thermal energy of the electrons; in the plasmasheet, E/sub 0parallel/=0.2--0.6 keV). The observed values for the field-aligned potential drop (V) usually range within the limits defined by this double inequality (i.e., 0.6 kVvery-much-less-thanVvery-much-less-than100 kV). The ohmic-like behavior of an auroral magnetic flux tube (J/sub parallel/proportionalV) and the constancy of epsilon/V/sup 2/ has been found experimentally by Lyons et al. (1979). Using an asymptotic expansion for the kinetic electron precipitation flux and energy flux we have obtained a useful formula which relates the Lyons-Evans-Lundin constant K(=epsilon/sub obs//V/sub obs//sup 2/) to the auroral electron density and temperature in the source region (i.e., in the plasmasheet).

252 citations



Journal ArticleDOI
TL;DR: In this article, it was shown that the final observed charge state of a field-evaporated ion can be explained by the occurrence of postionization whereby an ion being accelerated away from a metal surface in a strong electric field loses one or more electrons by tunneling into the substrate.
Abstract: It is shown that the final observed charge state of a field-evaporated ion can be explained by the occurrence of post-ionization whereby an ion being accelerated away from a metal surface in a strong electric field loses one or more electrons by tunneling into the substrate. Calculations using an approximate analytic formula derived from a simple model potential predict the probability of post-ionization for many different elements.

142 citations


Patent
02 Dec 1980
TL;DR: In this article, the authors present a method and apparatus for controlling the electric charge on droplets formed by the breaking up of a pressurized liquid stream at a drop formation point located within an electric field.
Abstract: Method and apparatus for controlling the electric charge on droplets formed by the breaking up of a pressurized liquid stream at a drop formation point located within an electric field The field is provided to have an electric potential gradient and means are provided to effect drop formation at a point in the field corresponding to the desired predetermined charge to be placed on the droplets at the point of their formation The location of the drop formation point within the charging field may be controlled by one or more signals applied to various components of the apparatus The method and apparatus are particularly suited to ink-jet recording systems

124 citations


Journal ArticleDOI
TL;DR: The great similarity of the boundary potential change to the R2 phase of the early receptor potential suggests that the two have the same molecular origin.

73 citations


Journal ArticleDOI
TL;DR: In this paper, it was shown that a large electrostatic potential difference must exist along the magnetic field lines under very general conditions, as a direct consequence of the interaction between a hot plasma and the Earth's magnetic field.

63 citations


Journal ArticleDOI
TL;DR: In this article, a theory of magnetosphere-ionosphere coupling in the presence of field-aligned potential drops is formulated within the framework of magnetohydrodynamic equations, allowing the magnetosphere as well as the ionosphere to respond self-consistently to the parallel potential drop along auroral field lines.
Abstract: A theory of magnetosphere-ionosphere coupling in the presence of field-aligned potential drops is formulated within the framework of magnetohydrodynamic equations. Our formulation allows the magnetosphere as well as the ionosphere to respond self-consistently to the parallel potential drop along auroral field lines. Equipotential contours are distorted into a V-shaped structure near the convection reversal boundary and S-shaped on the equatorward side, each gives rise to an inverted V precipitation band. The loading effect of the imperfect coupling results in a valley in the electric field profile which occurs equatorward of the convection reversal boundary.

Journal ArticleDOI
TL;DR: The general effective radial potentials for a spin-1/2 particle interacting with scalar, electric, and magnetic potentials are given in this paper, where it is shown that the magnetic potential provides a well deep enough to confine the massless particle.
Abstract: The general effective radial potentials for a spin‐ 1/2 particle interacting with scalar, electric, and magnetic potentials are given. In the m=0 limit, it is shown that the magnetic potential provides a well deep enough to confine the massless particle. In particular, there are exact zero‐energy solutions in which two of the four components of the massless particle are confined; only two can leak out into the asymptotic region. The scattering amplitude is analytic in the entire j plane, hence consists only of Regge poles.

Journal ArticleDOI
TL;DR: In this paper, a mechanism for oxide growth on an electrically isolated metal sample in the presence of an rf-excited oxygen plasma is considered, where the assumption is made that the rate of rf oxidation is limited by transport of ionic species through the already formed oxide layer.
Abstract: A mechanism is considered for oxide growth on an electrically isolated metal sample in the presence of an rf‐excited oxygen plasma. The assumption is made that the rate of rf oxidation is limited by transport of ionic species through the already‐formed oxide layer. Thermally activated hopping of ionic defects in the presence of electric fields due to the surface potential established by the rf discharge and modified by the space charge of the mobile ionic defects is hypothesized. The origin of the voltage across the oxide is discussed in terms of a balance between the transport of negatively charged O ions and transport of electron holes created by ion neutralization of positive ions from the plasma. This model is developed analytically and evaluated numerically by employing the continuum limit of hopping transport equations valid for the very‐high‐field limit. A three parameter fit gives excellent agreement of the theory with the published data of Greiner for the rf oxidation of lead. The fitting parameters are the voltage across the oxide film, the ionic diffusivity, and the rate at which the oxide is removed by sputtering. The resulting parameter values are shown to be in reasonable accord with available experimental data. Parametric curves are presented to illustrate the dependence of the kinetics on the various microscopic parameters. The dependence of the limiting thickness on the primary parameters is likewise presented. It is shown that the growth rate may be significantly retarded by high levels of space charge in the oxide.

Journal ArticleDOI
TL;DR: In this paper, it was shown that the potential difference in a primitive model of an an electric double layer must increase as the surface change density on the electrode is increased, which is called AIP.
Abstract: It is shown that the potential difference in a primitive model of an an electric double layer must increase as the surface change density on the electrode is increased. (AIP)

Journal ArticleDOI
TL;DR: The electric field along a magnetic neutral line of the O type can be estimated by the method previously applied by Alfven to neutral sheets, with the same result: the line integral of the electric field, multiplied by the elementary charge, is at most equal to twice the magnetic energy per particle.
Abstract: The electric field along a magnetic neutral line of the O type can be estimated by the method previously applied by Alfven to neutral sheets, with the same result: the line integral of the electric field along the neutral line, multiplied by the elementary charge, is at most equal to twice the magnetic energy per particle. The same upper limit, within a numerical factor of order unity, is obtained from a hydromagnetic calculation where the plasma flow toward the O line is balanced by outflow within the narrow region where the hydromagnetic coupling between the flow and the electric field breaks down. The same upper limit can also be derived from nonsteady models with a nonzero curl of the electric field (no E × B inflow) or with a nonzero divergence of the mass flux density (no outflow), as well as from a model that involves anomalous resistivity when the current density exceeds a threshold value. The derived upper limit implies that the maximum energy that is gained by a particle that drifts along the O line is not significantly greater than the typical energy of a plasma sheet particle; hence simple acceleration by electric fields along magnetic O lines cannot account for the energetic component of the charged particle population in the magnetotail.

Journal ArticleDOI
TL;DR: In this paper, the magnetic field associated with the propagating action potential in a frog sciatic nerve was measured by a system utilizing a SQUID magnetometer, signal averaging, and a novel ferrite core toroidal transformer.
Abstract: Records of the magnetic field associated with the propagating action potential in a frog sciatic nerve have been obtained. Peak fields of about 60 picotesla are measured by a system utilizing a SQUID magnetometer, signal averaging, and a novel ferrite‐core toroidal transformer. Design considerations for the latter are given and, for example, indicate that it need not have a large number of turns. A method is presented to obtain the net electric current threading the toroid by deconvolution of the magnetometer signal. This routine allows detailed magnetic or current profiles to be obtained of compound neural events.

Patent
15 Aug 1980
TL;DR: In this paper, the variation of the electric potential on both sides of a central electrode in a borehole, detecting the two levels of the borehole where the potential gradient is zero, and measuring the electric resistivity of the geological formation between these two levels.
Abstract: The method of the invention comprises determining the variation of the electric potential on both sides of a central electrode in a borehole, detecting the two levels of the borehole where the potential gradient is zero, and measuring the electric resistivity of the geological formation between these two levels.

Journal ArticleDOI
TL;DR: In this article, an efficient and kinetically unique method to induce transmembrane potentials in a suspension of membrane-bound vesicles is the application of an external macroscopic electric field.

Journal ArticleDOI
TL;DR: The electric field model provides an alternative means of cell-to-cell propagation between myocardial cells which is electrical in nature but does not require the presence of low-resistance connections between cells.

Journal ArticleDOI
TL;DR: In this paper, the steering of ion beamlets by aperture displacement is studied analytically and numerically for the case of triode extractors with large acceleration-deceleration ratios.
Abstract: The steering of ion beamlets by aperture displacement is studied analytically and numerically for the case of triode extractors with large acceleration‐deceleration ratios. Here the acceleration‐deceleration ratio e is defined by e≡Va/Vb, where Va and Vb are the potentials applied to the second and third grids of the extractor, relative to the beam forming grid at zero potential. Both slit and round apertures are examined. When the second‐order effects of space charge and potential sag in the extractor are included in the analysis, good agreement with numerical simulations is obtained.

Journal ArticleDOI
TL;DR: In this article, an equivalent electric circuit model is used to study the electrodynamic interactions of long orbiting metallic tethers with the ionospheric plasma and, in particular, to derive current and potential profiles along bare tethers.
Abstract: An equivalent electric circuit model is used to study the electrodynamic interactions of long orbiting metallic tethers with the ionospheric plasma and, in particular, to derive current and potential profiles along bare metallic tethers. In contrast with other models, this approach is dynamic, enabling both the transient behavior of the wire and its final equilibrium state to be derived. A comparison with the results of other models indicates the advantage of the present approach, especially in those cases where the internal resistance of the tether plays a major role in determining the current and potential distributions.

Journal ArticleDOI
TL;DR: In this article, the authors used a rocket-borne instrumentation to detect reflections of energetic electrons at possible electric field configurations parallel to the direction of the magnetic lines of force in an altitude range of several thousand kilometers above the ionosphere.
Abstract: Electron beam experiments using rocket-borne instrumentation will be discussed. The observations indicate that reflections of energetic electrons may occur at possible electric field configurations parallel to the direction of the magnetic lines of force in an altitude range of several thousand kilometers above the ionosphere.


Journal ArticleDOI
TL;DR: Electric potentials at regions near the two specific thiol groups, SH1 and SH2, of the heavy meromyosin molecule were studied by the fluorescence quenching technique and the value of the newly introduced electric potential was calculated on the basis of various assumptions.
Abstract: Electric potentials at regions near the two specific thiol groups, SH1 and SH2, of the heavy meromyosin (HMM) molecule were studied by the fluorescence quenching technique. The effects of binding of ATP to HMM upon the electric potentials were also studied. N-(p(2-Benzimidazolyl)phenyl)maleimide (BIPM) was used as a thiol-directed fluorescent reagent. Prior to the labeling of SH2 with BIPM, the SH1 group was blocked with N-ethylmaleimide (NEM). Iodide ions (I-), thallium ions (Tl+), and acrylamide were used as quenchers of fluorescence. The sign of the electric potential was collectively determined from the dependence of the Stern-Volmer constants upon the ionic strength of solutions. 1. The region near SH1 was at a negative electric potential, whereas the electric potential at the region near SH2 was almost zero. 2. On the addition of ATP, the fluorescence intensity of BIPM bound to SH1 was unchanged, whereas that of BIPM bound to SH2 was greatly decreased to about 50% of the original level. The fluorescence intensity recovered as the added ATP was split into ADP and orthophosphate, and became saturated. The saturated level of the fluorescence intensity was, however, smaller than the original one, due to binding of the produced ADP to HMM. 3. On the addition of ATP, the negative electric potential at the region near SH1 was unchanged, whereas a negative electric potential with large gradient was newly introduced at the region near SH2. The value of the newly introduced electric potential was calculated on the basis of various assumptions. These results are discussed in connection with the functions of myosin.

Journal ArticleDOI
TL;DR: In this paper, the authors describe the time-dependent changes which occur in Aloxide-Pb tunnel junctions as a result of voltage annealing (i.e., keeping a fixed bias across junction electrodes) and show that applying a voltage across the junction causes an accumulation or depletion of positive charge at the Aloxide interface depending on the polarity of the applied bias.
Abstract: This paper describes the time‐dependent changes which occur in Al‐oxide–Pb tunnel junctions as a result of voltage annealing (i.e., keeping a fixed bias across junction electrodes). By examining changes in junction resistance, barrier parameters (barrier thickness, average barrier height, and the separation between barrier heights at the two electrodes) and inelastic electron tunneling (IET) peak intensities, one finds that applying a voltage across the junction causes an accumulation or depletion of positive charge at the Al‐oxide interface depending on the polarity of the applied bias. Along with charge redistribution, the voltage‐induced electric field also enhances or retards other processes (such as reorientation of surface hydroxyl groups) which normally take place during thermal annealing.

Journal ArticleDOI
TL;DR: In this article, the local field correction near the surface of a dipolar crystal has been studied by explicitly computing the non-retarded electric field produced by a finite array of classical point dipoles induced by a time-varying electric field.

Journal ArticleDOI
TL;DR: In this paper, a direct and fourth order simulation of the electric potential and electric fields is presented, which is necessary for the simulation of semiperiodic plasma systems, and a method is presented which is direct and of fourth order.

Journal ArticleDOI
TL;DR: In this paper, the electron energy distribution in a magnetic multipole ion source has been measured utilizing a retarding potential energy analyzer, and the observed distribution of the primary electrons is spread out from the thermal population to energies 30% above the discharge energy.
Abstract: The electron energy distribution in a magnetic multipole ion source has been measured utilizing a retarding potential energy analyzer. The observed distribution of the primary electrons is spread out from the thermal population to energies 30% above the discharge energy. Implications on the theory of ionization efficiency are discussed.

Journal ArticleDOI
TL;DR: In this article, an experimental study of Au-polycrystalline GaAs Schottky barriers has been made, and the currentvoltage and capacitance-voltage characteristics of GaAs films of various grain sizes have been measured.
Abstract: An experimental study of Au‐polycrystalline GaAs Schottky barriers has been made. The current‐voltage and capacitance‐voltage characteristics of GaAs films of various grain sizes have been measured. Analysis of these data indicate that the transport may be electrode‐limited, bulk‐limited, or a combination of electrode‐limited and bulk‐limited conduction processes, depending upon the (average) grain size.

Journal ArticleDOI
TL;DR: The similarity of the boundary potential change to the R2 phase of the early receptor potential suggests that the two have the same molecular origin.
Abstract: — A rapid change in an interfacial electric potential of isolated bovine rod outer-segment disc membranes occurs upon illumination. This potential change, which has been detected by the use of spin labelled hydrophobic ions, apparently occurs within a low dielectric boundary region of the membrane near the external (cytoplasmic) surface and is positive with respect to the aqueous exterior of the disk. The magnitude of the potential change is pH and temperature dependent and appears with a first-order half-time of approximately 5 ms at 23°C. A simple model in which one positive charge per bleached rhodopsin is translocated from the cytoplasmic aqueous space into the membrane low dielectric boundary region readily accounts for all experimental observations. The similarity of the boundary potential change to the R2 phase of the early receptor potential suggests that the two have the same molecular origin.