Spin current and electrical polarization in GaN double-barrier structures

OpenAIRE

Litvinov, V. I.

2007-01-01

Tunnel spin polarization in a piezoelectric AlGaN/GaN double barrier structure is calculated. It is shown that the piezoelectric field and the spontaneous electrical polarization increase an efficiency of the tunnel spin injection. The relation between the electrical polarization and the spin orientation allows engineering a zero magnetic field spin injection manipulating the lattice-mismatch strain with an Al-content in the barriers.

Characteristics of Superjunction Lateral-Double-Diffusion Metal Oxide Semiconductor Field Effect Transistor and Degradation after Electrical Stress

Science.gov (United States)

Lin, Jyh‑Ling; Lin, Ming‑Jang; Lin, Li‑Jheng

2006-04-01

The superjunction lateral double diffusion metal oxide semiconductor field effect has recently received considerable attention. Introducing heavily doped p-type strips to the n-type drift region increases the horizontal depletion capability. Consequently, the doping concentration of the drift region is higher and the conduction resistance is lower than those of conventional lateral-double-diffusion metal oxide semiconductor field effect transistors (LDMOSFETs). These characteristics may increase breakdown voltage (\\mathit{BV}) and reduce specific on-resistance (Ron,sp). In this study, we focus on the electrical characteristics of conventional LDMOSFETs on silicon bulk, silicon-on-insulator (SOI) LDMOSFETs and superjunction LDMOSFETs after bias stress. Additionally, the \\mathit{BV} and Ron,sp of superjunction LDMOSFETs with different N/P drift region widths and different dosages are discussed. Simulation tools, including two-dimensional (2-D) TSPREM-4/MEDICI and three-dimensional (3-D) DAVINCI, were employed to determine the device characteristics.

Nonlinear optical rectification and optical absorption in GaAs-Ga1-xAlxAs asymmetric double quantum wells: Combined effects of applied electric and magnetic fields and hydrostatic pressure

International Nuclear Information System (INIS)

Karabulut, I.; Mora-Ramos, M.E.; Duque, C.A.

2011-01-01

The intersubband electron-related nonlinear optical absorption and nonlinear optical rectification in GaAs-Ga 1-x Al x As asymmetric double quantum wells are studied, under the influence of combined or independent applied electric and magnetic fields as well as hydrostatic pressure. The outcome of the density matrix formalism and the effective mass, and parabolic-band approximations have been considered as main theoretical tools for the description. It is obtained that under particular geometrical conditions, with or without electric and/or magnetic field strength, the optical rectification is null and, simultaneously, in such circumstances the optical absorption has a relative maximum. It is also detected that the influence of the hydrostatic pressure leads to increasing or decreasing behaviors of the nonlinear optical absorption in dependence of the particular regime of pressure values considered, with significant distinction of the cases of opposite electric field orientations. - Highlights: → Maxima of the NOA correspond to zero in the NOR. → Electric fields can couple the double quantum wells. → Hydrostatic pressure can couple the double quantum wells. → NOA can increase/decrease with hydrostatic pressure. → Overlap between wave functions depends on the magnetic field.

Modeling of anisotropic properties of double quantum rings by the terahertz laser field.

Science.gov (United States)

Baghramyan, Henrikh M; Barseghyan, Manuk G; Kirakosyan, Albert A; Ojeda, Judith H; Bragard, Jean; Laroze, David

2018-04-18

The rendering of different shapes of just a single sample of a concentric double quantum ring is demonstrated realizable with a terahertz laser field, that in turn, allows the manipulation of electronic and optical properties of a sample. It is shown that by changing the intensity or frequency of laser field, one can come to a new set of degenerated levels in double quantum rings and switch the charge distribution between the rings. In addition, depending on the direction of an additional static electric field, the linear and quadratic quantum confined Stark effects are observed. The absorption spectrum shifts and the additive absorption coefficient variations affected by laser and electric fields are discussed. Finally, anisotropic electronic and optical properties of isotropic concentric double quantum rings are modeled with the help of terahertz laser field.

Asymptotic theory of double layer and shielding of electric field at the edge of illuminated plasma

Energy Technology Data Exchange (ETDEWEB)

Benilov, M. S. [Departamento de Física, CCCEE, Universidade da Madeira, Largo do Município, 9000 Funchal (Portugal); Thomas, D. M. [Blackett Laboratory, Imperial College London, Prince Consort Road, London SW7 2BW (United Kingdom)

2014-04-15

The method of matched asymptotic expansions is applied to the problem of a collisionless plasma generated by UV illumination localized in a central part of the plasma in the limiting case of small Debye length λ{sub D}. A second-approximation asymptotic solution is found for the double layer positioned at the boundary of the illuminated region and for the un-illuminated plasma for the plane geometry. Numerical calculations for different values of λ{sub D} are reported and found to confirm the asymptotic results. The net integral space charge of the double layer is asymptotically small, although in the plane geometry it is just sufficient to shield the ambipolar electric field existing in the illuminated region and thus to prevent it from penetrating into the un-illuminated region. The double layer has the same mathematical nature as the intermediate transition layer separating an active plasma and a collisionless sheath, and the underlying physics is also the same. In essence, the two layers represent the same physical object: a transonic layer.

Electroresistance effect in gold thin film induced by ionic-liquid-gated electric double layer

International Nuclear Information System (INIS)

Nakayama, Hiroyasu; Ohtani, Takashi; Fujikawa, Yasunori; Ando, Kazuya; Saitoh, Eiji; Ye, Jianting; Iwasa, Yoshihiro

2012-01-01

Electroresistance effect was detected in a metallic thin film using ionic-liquid-gated electric-double-layer transistors (EDLTs). We observed reversible modulation of the electric resistance of a Au thin film. In this system, we found that an electric double layer works as a nanogap capacitor with 27 (-25) MV cm -1 of electric field by applying only 1.7 V of positive (negative) gate voltage. The experimental results indicate that the ionic-liquid-gated EDLT technique can be used for controlling the surface electronic states on metallic systems. (author)

Current limitation and formation of plasma double layers in a non-uniform magnetic field

International Nuclear Information System (INIS)

Plamondon, R.; Teichmann, J.; Torven, S.

1986-07-01

Formation of strong double layers has been observed experimentally in a magnetised plasma column maintained by a plasma source. The magnetic field is approximately axially homogenous except in a region at the anode where the electric current flows into a magnetic mirror. The double layer has a stationary position only in the region of non-uniform magnetic field or at the aperture separating the source and the plasma column. It is characterized by a negative differential resistance in the current-voltage characteristic of the device. The parameter space,where the double layer exists, has been studied as well as the corresponding potential profiles and fluctuation spectra. The electric current and the axial electric field are oppositely directed between the plasma source and a potential minimum which is formed in the region of inhomogeneous magnetic field. Electron reflection by the resulting potential barrier is found to be an important current limitation mechanism. (authors)

The time-dependent development of electric double-layers in saline solutions

International Nuclear Information System (INIS)

Morrow, R; McKenzie, D R; Bilek, M M M

2006-01-01

We have studied the time-dependent development of electric double-layers (ionic sheaths) in saline solutions by simultaneously solving the sodium and chlorine ion continuity equations coupled with Poisson's equation in one dimension. The study of the effects of time-varying electric fields in solution is relevant to the possible health effect of radio-frequency electric fields on cells in the human body and to assessing the potential of using external electric fields to orient proteins for attachment to surfaces for biosensing applications. Our calculations, for applied voltages of 10-175 mV between the electrode and the solution, predict time scales of ∼0.1-110 μs for the formation of double-layers in solutions of concentration between 0.001 and 1.0 M. We develop an empirical equation that can predict the double-layer formation time to within 10% over this wide parameter range. The method has been validated by comparing the solutions obtained, once the program has run to a steady state, with the standard non-linear Poisson-Boltzmann equations. Excellent agreement is found with the Gouy-Chapman solution of the non-linear Poisson-Boltzmann equation. Thus the method is not restricted in accuracy and applicability as is the case for the linear Poisson-Boltzmann equation. The method can also provide solutions for cases where there are orders of magnitude changes in the ion densities; this has not been the case for previous studies where small perturbation analysis has been employed. The method developed here can readily be extended to two and three dimensions using time-splitting methods

Optical and Electrical Characteristics of Graphene Double Layer Formed by a Double Transfer of Graphene Single Layers.

Science.gov (United States)

Kim, Young Jun; Bae, Gi Yoon; Chun, Sungwoo; Park, Wanjun

2016-03-01

We demonstrate formation of double layer graphene by means of a double transfer using two single graphene layers grown by a chemical vapor deposition method. It is observed that shiftiness and broadness in the double-resonance of Raman scattering are much weaker than those of bilayer graphene formed naturally. Transport characteristics examined from transmission line measurements and field effect transistors show the similar behavior with those of single layer graphene. It indicates that interlayer separation, in electrical view, is large enough to avoid correlation between layers for the double layer structure. It is also observed from a transistor with the double layer graphene that molecules adsorpted on two inner graphene surfaces in the double layered structure are isolated and conserved from ambient environment.

The electric double layer at a metal electrode in pure water

Science.gov (United States)

Brüesch, Peter; Christen, Thomas

2004-03-01

Pure water is a weak electrolyte that dissociates into hydronium ions and hydroxide ions. In contact with a charged electrode a double layer forms for which neither experimental nor theoretical studies exist, in contrast to electrolytes containing extrinsic ions like acids, bases, and solute salts. Starting from a self-consistent solution of the one-dimensional modified Poisson-Boltzmann equation, which takes into account activity coefficients of point-like ions, we explore the properties of the electric double layer by successive incorporation of various correction terms like finite ion size, polarization, image charge, and field dissociation. We also discuss the effect of the usual approximation of an average potential as required for the one-dimensional Poisson-Boltzmann equation, and conclude that the one-dimensional approximation underestimates the ion density. We calculate the electric potential, the ion distributions, the pH-values, the ion-size corrected activity coefficients, and the dissociation constants close to the electric double layer and compare the results for the various model corrections.

Two-electron states in double quantum dot in direct electric field

International Nuclear Information System (INIS)

Burdov, V.A.

2001-01-01

One determined analytically the wave functions of stationary states and the spectrum of two-electron system in symmetric binary quantum point. It is shown that in the normal state at the absence of external electric field the electrons due to the Coulomb blockade can not be collectively in one quantum point. In the external electric field the situation changes. When a certain critical value of field intensity is reached the probability of detection of both electrons in one quantum point by a jump increases from zero up to 1 [ru

Asymmetric GaAs n-type double δ-doped quantum wells as a source of intersubband-related nonlinear optical response: Effects of an applied electric field

International Nuclear Information System (INIS)

Rodríguez-Magdaleno, K.A.; Martínez-Orozco, J.C.; Rodríguez-Vargas, I.; Mora-Ramos, M.E.; Duque, C.A.

2014-01-01

In this work, the conduction band electron states and the associated intersubband-related linear and nonlinear optical absorption coefficient and relative refractive index change are calculated for an asymmetric double n-type δ-doped quantum well in a GaAs-matrix. The effects of an external applied static electric field are included. Values of the two-dimensional impurities density (N 2d ) of each single δ-doped quantum well are taken to vary within the range of 1.0×10 12 to 7.0×10 12 cm −2 , consistent with the experimental data growth regime. The optical responses are reported as a function of the δ-doped impurities density and the applied electric field. It is shown that single electron states and the related optical quantities are significantly affected by the structural asymmetry of the double δ-doped quantum well system. In addition, a brief comparison with the free-carrier-related optical response is presented. -- Highlights: • Nonlinear optics in asymmetric double n-type δ-doped quantum well in a GaAs-matrix. • The system is considered under external applied electric field in growth direction. • The 2D impurity density is consistent with the experimental data growth regime. • The optical quantities are significantly affected by the structural asymmetry of the system

Asymmetric GaAs n-type double δ-doped quantum wells as a source of intersubband-related nonlinear optical response: Effects of an applied electric field

Energy Technology Data Exchange (ETDEWEB)

Rodríguez-Magdaleno, K.A.; Martínez-Orozco, J.C.; Rodríguez-Vargas, I. [Unidad Académica de Física, Universidad Autónoma de Zacatecas, Calz. Solidaridad Esq. Paseo a La Bufa S/N. C.P. 98060 Zacatecas (Mexico); Mora-Ramos, M.E. [Facultad de Ciencias, Universidad Autónoma del Estado de Morelos, Av. Universidad 1001, CP 62209 Cuernavaca, Morelos (Mexico); Física Teórica y Aplicada, Escuela de Ingeniería de Antioquia, AA 7516 Medellín (Colombia); Grupo de Materia Condensada-UdeA, Instituto de Física, Facultad de Ciencias Exactas y Naturales, Universidad de Antioquia UdeA, Calle 70 No. 52-21, Medellín (Colombia); Duque, C.A., E-mail: cduque@fisica.udea.edu.co [Grupo de Materia Condensada-UdeA, Instituto de Física, Facultad de Ciencias Exactas y Naturales, Universidad de Antioquia UdeA, Calle 70 No. 52-21, Medellín (Colombia)

2014-03-15

In this work, the conduction band electron states and the associated intersubband-related linear and nonlinear optical absorption coefficient and relative refractive index change are calculated for an asymmetric double n-type δ-doped quantum well in a GaAs-matrix. The effects of an external applied static electric field are included. Values of the two-dimensional impurities density (N{sub 2d}) of each single δ-doped quantum well are taken to vary within the range of 1.0×10{sup 12} to 7.0×10{sup 12} cm{sup −2}, consistent with the experimental data growth regime. The optical responses are reported as a function of the δ-doped impurities density and the applied electric field. It is shown that single electron states and the related optical quantities are significantly affected by the structural asymmetry of the double δ-doped quantum well system. In addition, a brief comparison with the free-carrier-related optical response is presented. -- Highlights: • Nonlinear optics in asymmetric double n-type δ-doped quantum well in a GaAs-matrix. • The system is considered under external applied electric field in growth direction. • The 2D impurity density is consistent with the experimental data growth regime. • The optical quantities are significantly affected by the structural asymmetry of the system.

Problems related to macroscopic electric fields in the magnetosphere

International Nuclear Information System (INIS)

Faelthammar, C.

1977-01-01

The macroscopic electric fields in the magnetosphere originate from internal as well as external sources. The fields are intimately coupled with the dynamics of magnetospheric plasma convection. They also depend on the complicated electrical properties of the hot collisionless plasma. Macroscopic electric fields are responsible for some important kinds of energization of charged particles that take place in the magnetosphere and affect not only particles of auroral energy but also, by multistep processes, trapped high-energy particles. A particularly interesting feature of magnetospheric electric fields is that they can have substantial components along the geomagnetic field, as has recently been confirmed by observations. Several physical mechanisms have been identified by which such electric fields can be supported even when collisions between particles are negligible. Comments are made on the magnetic mirror effect, anomalous resistivity, the collisionless thermoelectric effect, and electric double layers, emphasizing key features and differences and their significance in the light of recent observational data

Electric potential calculation in molecular simulation of electric double layer capacitors

International Nuclear Information System (INIS)

Wang, Zhenxing; Laird, Brian B; Olmsted, David L; Asta, Mark

2016-01-01

For the molecular simulation of electric double layer capacitors (EDLCs), a number of methods have been proposed and implemented to determine the one-dimensional electric potential profile between the two electrodes at a fixed potential difference. In this work, we compare several of these methods for a model LiClO 4 -acetonitrile/graphite EDLC simulated using both the traditional fixed-charged method (FCM), in which a fixed charge is assigned a priori to the electrode atoms, or the recently developed constant potential method (CPM) (2007 J. Chem. Phys . 126 084704), where the electrode charges are allowed to fluctuate to keep the potential fixed. Based on an analysis of the full three-dimensional electric potential field, we suggest a method for determining the averaged one-dimensional electric potential profile that can be applied to both the FCM and CPM simulations. Compared to traditional methods based on numerically solving the one-dimensional Poisson’s equation, this method yields better accuracy and no supplemental assumptions. (paper)

The role of magnetic-field-aligned electric fields in auroral acceleration

International Nuclear Information System (INIS)

Block, L.P.; Faelthammar, C.G.

1990-01-01

Electric field measurements on the Swedish satellite Viking have confirmed and extended earlier observations on S3-3 and provided further evidence of the role of dc electric fields in auroral acceleration processes. On auroral magnetic field lines the electric field is strongly fluctuating both transverse and parallel to the magnetic field. The significance of these fluctuations for the auroral acceleration process is discussed. A definition of dc electric fields is given in terms of their effects on charged particles. Fluctuations below several hertz are experienced as dc by typical auroral electrons if the acceleration length is a few thousand kilometers. For ions the same is true below about 0.1 Hz. The magnetic-field-aligned (as well as the transverse) component of the electric field fluctuations has a maximum below 1 Hz, in a frequency range that appears as dc to the electrons but not to the ions. This allows it to cause a selective acceleration, which may be important in explaining some of the observed characteristics of auroral particle distributions. The electric field observations on Viking support the conclusion that magnetic-field-aligned potential drops play an important role in auroral acceleration, in good agreement with particle observations boht on Viking and on the DE satellites. They also show that a large part, or even all, of the accelerating potential drop may be accounted for by numerous weak (about a volt) electric double layers, in agreement with earlier observations on the S3-3 satellite and with an early theoretical suggestion by L. Block

Absorption coefficient and relative refractive index change for a double δ-doped GaAs MIGFET-like structure: Electric and magnetic field effects

Science.gov (United States)

Martínez-Orozco, J. C.; Rodríguez-Magdaleno, K. A.; Suárez-López, J. R.; Duque, C. A.; Restrepo, R. L.

2016-04-01

In this work we present theoretical results for the electronic structure as well as for the absorption coefficient and relative refractive index change for an asymmetric double δ-doped like confining potential in the active region of a Multiple Independent Gate Field Effect Transistor (MIGFET) system. We model the potential profile as a double δ-doped like potential profile between two Schottky (parabolic) potential barriers that are just the main characteristics of the MIGFET configuration. We investigate the effect of external electromagnetic fields in this kind of quantum structures, in particular we applied a homogeneous constant electric field in the growth direction z as well as a homogeneous constant magnetic field in the x-direction. In general we conclude that by applying electromagnetic fields we can modulate the resonant peaks of the absorption coefficient as well as their energy position. Also with such probes it is possible to control the nodes and amplitude of the relative refractive index changes related to resonant intersubband optical transitions.

Single channel double-duct liquid metal electrical generator using a magnetohydrodynamic device

Science.gov (United States)

Haaland, Carsten M.; Deeds, W. Edward

1999-01-01

A single channel double-duct liquid metal electrical generator using a magnetohydrodynamic (MHD) device. The single channel device provides useful output AC electric energy. The generator includes a two-cylinder linear-piston engine which drives liquid metal in a single channel looped around one side of the MHD device to form a double-duct contra-flowing liquid metal MHD generator. A flow conduit network and drive mechanism are provided for moving liquid metal with an oscillating flow through a static magnetic field to produce useful AC electric energy at practical voltages and currents. Variable stroke is obtained by controlling the quantity of liquid metal in the channel. High efficiency is obtained over a wide range of frequency and power output.

Electric-line-source illumination of a circular cylinder of lossless double-negative material: an investigation of near field, directivity, and radiation resistance

DEFF Research Database (Denmark)

Arslanagic, Samel; Breinbjerg, Olav

2006-01-01

the properties of the near field, inside as well as outside the cylinder, and the far-field. Third, the variations of these fields are examined, as well as the radiation resistance and radiation pattern, as functions of the geometrical and electromagnetic parameters of the configuration. It is demonstrated......This work investigates the properties of an antenna-like configuration with an electric line source radiating in the presence of a double-negative circular cylinder. First, the analytical eigenfunction-series solution is derived. Second, this solution is employed in numerical calculations to study...

Spin-orbit coupling and electric-dipole spin resonance in a nanowire double quantum dot.

Science.gov (United States)

Liu, Zhi-Hai; Li, Rui; Hu, Xuedong; You, J Q

2018-02-02

We study the electric-dipole transitions for a single electron in a double quantum dot located in a semiconductor nanowire. Enabled by spin-orbit coupling (SOC), electric-dipole spin resonance (EDSR) for such an electron can be generated via two mechanisms: the SOC-induced intradot pseudospin states mixing and the interdot spin-flipped tunneling. The EDSR frequency and strength are determined by these mechanisms together. For both mechanisms the electric-dipole transition rates are strongly dependent on the external magnetic field. Their competition can be revealed by increasing the magnetic field and/or the interdot distance for the double dot. To clarify whether the strong SOC significantly impact the electron state coherence, we also calculate relaxations from excited levels via phonon emission. We show that spin-flip relaxations can be effectively suppressed by the phonon bottleneck effect even at relatively low magnetic fields because of the very large g-factor of strong SOC materials such as InSb.

The Vector Electric Field Investigation on the C/NOFS Satellite

Science.gov (United States)

Pfaff, R.; Acuna, M.; Kujawski, J.; Fourre, R.; Uribe, P.; Hunsaker, F.; Rowland, D.; Le, G.; Farrell, W.; Maynard, N.;

Electric Field-Controlled Ion Transport In TiO2 Nanochannel.

Science.gov (United States)

Li, Dan; Jing, Wenheng; Li, Shuaiqiang; Shen, Hao; Xing, Weihong

2015-06-03

On the basis of biological ion channels, we constructed TiO2 membranes with rigid channels of 2.3 nm to mimic biomembranes with flexible channels; an external electric field was employed to regulate ion transport in the confined channels at a high ionic strength in the absence of electrical double layer overlap. Results show that transport rates for both Na+ and Mg2+ were decreased irrespective of the direction of the electric field. Furthermore, a voltage-gated selective ion channel was formed, the Mg2+ channel closed at -2 V, and a reversed relative electric field gradient was at the same order of the concentration gradient, whereas the Na+ with smaller Stokes radius and lower valence was less sensitive to the electric field and thus preferentially occupied and passed the channel. Thus, when an external electric field is applied, membranes with larger nanochannels have promising applications in selective separation of mixture salts at a high concentration.

Electric field-induced valley degeneracy lifting in uniaxial strained graphene: Evidence from magnetophonon resonance

Science.gov (United States)

Assili, Mohamed; Haddad, Sonia; Kang, Woun

2015-03-01

A double peak structure in the magnetophonon resonance (MPR) spectrum of uniaxial strained graphene, under crossed electric and magnetic fields, is predicted. We focus on the Γ point optical phonon modes coupled to the inter-Landau level transitions 0 ⇆±1 where MPR is expected to be more pronounced at high magnetic field. We derive the frequency shifts and the broadenings of the longitudinal and transverse optical phonon modes taking into account the effect of the strain modified electronic spectrum on the electron-phonon coupling. We show that the MPR line for a given phonon mode acquires a double peak structure originating from the twofold valley degeneracy lifting. The latter is due to the different Landau level spacings in the two Dirac valleys resulting from the simultaneous action of the inplane electric field and the strain-induced Dirac cone tilt. We discuss the role of some key parameters such as disorder, strain, doping, and electric field amplitude on the emergence of the double peak structure.

Dielectric-spectroscopy approach to ferrofluid nanoparticle clustering induced by an external electric field.

Science.gov (United States)

Rajnak, Michal; Kurimsky, Juraj; Dolnik, Bystrik; Kopcansky, Peter; Tomasovicova, Natalia; Taculescu-Moaca, Elena Alina; Timko, Milan

2014-09-01

An experimental study of magnetic colloidal particles cluster formation induced by an external electric field in a ferrofluid based on transformer oil is presented. Using frequency domain isothermal dielectric spectroscopy, we study the influence of a test cell electrode separation distance on a low-frequency relaxation process. We consider the relaxation process to be associated with an electric double layer polarization taking place on the particle surface. It has been found that the relaxation maximum considerably shifts towards lower frequencies when conducting the measurements in the test cells with greater electrode separation distances. As the electric field intensity was always kept at a constant value, we propose that the particle cluster formation induced by the external ac electric field accounts for that phenomenon. The increase in the relaxation time is in accordance with the Schwarz theory of electric double layer polarization. In addition, we analyze the influence of a static electric field generated by dc bias voltage on a similar shift in the relaxation maximum position. The variation of the dc electric field for the hysteresis measurements purpose provides understanding of the development of the particle clusters and their decay. Following our results, we emphasize the utility of dielectric spectroscopy as a simple, complementary method for detection and study of clusters of colloidal particles induced by external electric field.

Capacitance of carbon-based electrical double-layer capacitors.

Science.gov (United States)

Ji, Hengxing; Zhao, Xin; Qiao, Zhenhua; Jung, Jeil; Zhu, Yanwu; Lu, Yalin; Zhang, Li Li; MacDonald, Allan H; Ruoff, Rodney S

2014-01-01

Experimental electrical double-layer capacitances of porous carbon electrodes fall below ideal values, thus limiting the practical energy densities of carbon-based electrical double-layer capacitors. Here we investigate the origin of this behaviour by measuring the electrical double-layer capacitance in one to five-layer graphene. We find that the capacitances are suppressed near neutrality, and are anomalously enhanced for thicknesses below a few layers. We attribute the first effect to quantum capacitance effects near the point of zero charge, and the second to correlations between electrons in the graphene sheet and ions in the electrolyte. The large capacitance values imply gravimetric energy storage densities in the single-layer graphene limit that are comparable to those of batteries. We anticipate that these results shed light on developing new theoretical models in understanding the electrical double-layer capacitance of carbon electrodes, and on opening up new strategies for improving the energy density of carbon-based capacitors.

Transport properties of Dirac electrons in graphene based double velocity-barrier structures in electric and magnetic fields

International Nuclear Information System (INIS)

Liu, Lei; Li, Yu-Xian; Liu, Jian-Jun

2012-01-01

Using transfer matrix method, transport properties in graphene based double velocity-barrier structures under magnetic and electric fields are numerically studied. It is found that velocity barriers for the velocity ratio (the Fermi velocity inside the barrier to that outside the barrier) less than one (or for the velocity ratio greater than one) have properties similar to electrostatic wells (or barriers). The velocity barriers for the velocity ratio greater than one significantly enlarge the resonant tunneling region of electrostatic barriers. In the presence of magnetic field, the plateau width of the Fano factor with a Poissonian value shortens (or broadens) for the case of the velocity ratio less than one (or greater than one). When the Fermi energy is equal to the electrostatic barrier height, for different values of the velocity ratio, both the conductivities and the Fano factors remain fixed. -- Highlights: ► We model graphene based velocity-barrier structures in electric and magnetic fields. ► Velocity barrier for ξ 1) have property similar to electrostatic well (barrier). ► Velocity barrier for ξ>1 enlarge the resonant tunneling region of electrostatic barrier. ► The plateau width of Fano factor shortens (or broadens) for the case of ξ 1). ► The conductivity remains fixed at the point of E F =U 0 for different values of ξ.

Electrophoresis in strong electric fields.

Science.gov (United States)

Barany, Sandor

2009-01-01

Two kinds of non-linear electrophoresis (ef) that can be detected in strong electric fields (several hundred V/cm) are considered. The first ("classical" non-linear ef) is due to the interaction of the outer field with field-induced ionic charges in the electric double layer (EDL) under conditions, when field-induced variations of electrolyte concentration remain to be small comparatively to its equilibrium value. According to the Shilov theory, the non-linear component of the electrophoretic velocity for dielectric particles is proportional to the cubic power of the applied field strength (cubic electrophoresis) and to the second power of the particles radius; it is independent of the zeta-potential but is determined by the surface conductivity of particles. The second one, the so-called "superfast electrophoresis" is connected with the interaction of a strong outer field with a secondary diffuse layer of counterions (space charge) that is induced outside the primary (classical) diffuse EDL by the external field itself because of concentration polarization. The Dukhin-Mishchuk theory of "superfast electrophoresis" predicts quadratic dependence of the electrophoretic velocity of unipolar (ionically or electronically) conducting particles on the external field gradient and linear dependence on the particle's size in strong electric fields. These are in sharp contrast to the laws of classical electrophoresis (no dependence of V(ef) on the particle's size and linear dependence on the electric field gradient). A new method to measure the ef velocity of particles in strong electric fields is developed that is based on separation of the effects of sedimentation and electrophoresis using videoimaging and a new flowcell and use of short electric pulses. To test the "classical" non-linear electrophoresis, we have measured the ef velocity of non-conducting polystyrene, aluminium-oxide and (semiconductor) graphite particles as well as Saccharomice cerevisiae yeast cells as a

Control of magnetism in Co by an electric field

Science.gov (United States)

Chiba, D.; Ono, T.

2013-05-01

In this paper, we review the recent experimental developments on electric-field switching of ferromagnetism in ultra-thin Co films. The application of an electric field changes the electron density at the surface of the Co film, which results in modulation of its Curie temperature. A capacitor structure consisting of a gate electrode, a solid-state dielectric insulator and a Co bottom electrode is used to observe the effect. To obtain a larger change in the electron density, we also fabricated an electric double-layer capacitor structure using an ionic liquid. A large change in the Curie temperature of ∼100 K across room temperature is achieved with this structure. The application of the electric field influences not only the Curie temperature but also the domain-wall motion. A change in the velocity of a domain wall prepared in a Co micro-wire of more than one order of magnitude is observed. Possible mechanisms to explain the above-mentioned electric-field effects in Co ultra-thin films are discussed.

Control of magnetism in Co by an electric field

International Nuclear Information System (INIS)

Chiba, D; Ono, T

2013-01-01

In this paper, we review the recent experimental developments on electric-field switching of ferromagnetism in ultra-thin Co films. The application of an electric field changes the electron density at the surface of the Co film, which results in modulation of its Curie temperature. A capacitor structure consisting of a gate electrode, a solid-state dielectric insulator and a Co bottom electrode is used to observe the effect. To obtain a larger change in the electron density, we also fabricated an electric double-layer capacitor structure using an ionic liquid. A large change in the Curie temperature of ∼100 K across room temperature is achieved with this structure. The application of the electric field influences not only the Curie temperature but also the domain-wall motion. A change in the velocity of a domain wall prepared in a Co micro-wire of more than one order of magnitude is observed. Possible mechanisms to explain the above-mentioned electric-field effects in Co ultra-thin films are discussed. (topical review)

Nonpremixed flame in a counterflow under electric fields

KAUST Repository

Park, Daegeun

2016-05-08

Electrically assisted combustion has been studied in order to control or improve flame characteristics, and emphasizing efficiency and emission regulation. Many phenomenological observations have been reported on the positive impact of electric fields on flame, however there is a lack of detailed physical mechanisms for interpreting these. To clarify the effects of electric fields on flame, I have investigated flame structure, soot formation, and flow field with ionic wind electrical current responses in nonpremixed counterflow flames. The effects of direct current (DC) electric field on flame movement and flow field was also demonstrated in premixed Bunsen flames. When a DC electric field was applied to a lower nozzle, the flames moved toward the cathode side due to Lorentz force action on the positive ions, soot particles simultaneously disappeared completely and laser diagnostics was used to identify the results from the soot particles. To understand the effects of an electric field on flames, flow visualization was performed by Mie scattering to check the ionic wind effect, which is considered to play an important role in electric field assisted combustion. Results showed a bidirectional ionic wind, with a double-stagnant flow configuration, which blew from the flame (ionic source) toward both the cathode and the anode. This implies that the electric field affects strain rate and the axial location of stoichiometry, important factors in maintaining nonpremixed counterflow flames; thus, soot formation of the counterflow flame can also be affected by the electric field. In a test of premixed Bunsen flames having parallel electrodes, flame movement toward the cathode and bidirectional ionic wind were observed. Using PIV measurement it was found that a created radial velocity caused by positive ions (i.e. toward a cathode), was much faster than the velocity toward the anode. Even in a study of alternating current (AC) electric fields, bidirectional ionic wind could

Plasmasheet boundary electric fields during substorms

International Nuclear Information System (INIS)

Pedersen, A.

1985-01-01

Electric field data from the ISEE-1 and GEOS-2 satellites have been studied during two substorms when ISEE-1 was in a favourable position in the magneto-tail and GEOS-2 was in the afternoon/evening sector of the geostationary orbit. Both electric field measurements were carried out with spherical double probes, separately by 73.5 m on ISEE-1, and 42 m on GEOS-2. In one case GEOS-2, in the afternoon sector, detected an increase of the dawn-to-dusk electric field during plasmasheet thinning and approximately 10 minutes prior to a substorm expansion. At the time of this expansion ISEE-1 was most likely near an X-line, on the Earthward side and detected Earthward antiE x antiB velocities, in excess of 500 km s -1 . In another example ISEE-1 was most likely near an X-line, on the tailward side, and observed tailward antiE x antiB velocities which were followed, 5-20 minutes later, by characteristic oscillating electric fields (time scales of 10s-30s) on GEOS-2 near 23 local time. Such signatures have on many occasions been connected with observations of westward travelling surges near the GEOS-2 conjugated area in Scandinavia. The ISEE-1 observations of large-dawn-to-dusk electric fields were concentrated to the outer boundary of the plasmasheet, and in the case of the westward travelling surge. GEOS-2 was most likely at the inner, Earthward edge of the plasmasheet. Time delays between ISEE-1 and GEOS-2 indicate a propagation velocity comparable to the antiE x antiB velocity

Electric field tuning of phase separation in manganite thin films

KAUST Repository

Lourembam, James; Wu, Jianchun; Ding, Junfeng; Lin, Weinan; Wu, Tao

2014-01-01

In this paper, we investigate the electric field effect on epitaxial Pr0.65(Ca0.75Sr0.25)0.35MnO3 thin films in electric double-layer transistors. Different from the conventional transistors with semiconducting channels, the sub(micrometer)-scale phase separation in the manganite channels is expected to result in inhomogeneous distribution of mobile carriers and local enhancement of electric field. The field effect is much larger in the low-temperature phase separation region compared to that in the high-temperature polaron transport region. Further enhancement of electroresistance is achieved by applying a magnetic field, and a 250% modulation of resistance is observed at 80 K, equivalent to an increase of the ferromagnetic metallic phase fraction by 0.51%, as estimated by the general effective medium model. Our results illustrate the complementary nature of electric and magnetic field effects in phase-separated manganites, providing insights on such novel electronic devices based on complex oxides.

Electric field tuning of phase separation in manganite thin films

KAUST Repository

Lourembam, James

2014-01-29

In this paper, we investigate the electric field effect on epitaxial Pr0.65(Ca0.75Sr0.25)0.35MnO3 thin films in electric double-layer transistors. Different from the conventional transistors with semiconducting channels, the sub(micrometer)-scale phase separation in the manganite channels is expected to result in inhomogeneous distribution of mobile carriers and local enhancement of electric field. The field effect is much larger in the low-temperature phase separation region compared to that in the high-temperature polaron transport region. Further enhancement of electroresistance is achieved by applying a magnetic field, and a 250% modulation of resistance is observed at 80 K, equivalent to an increase of the ferromagnetic metallic phase fraction by 0.51%, as estimated by the general effective medium model. Our results illustrate the complementary nature of electric and magnetic field effects in phase-separated manganites, providing insights on such novel electronic devices based on complex oxides.

Electric field measurements at subcritical, oblique bow shock crossings

International Nuclear Information System (INIS)

Wygant, J.R.; Bensadoun, M.; Mozer, F.S.

1987-01-01

Electric field measurements at oblique, subcritical bow shock crossings are presented from the ISEE 1 University of California, Berkeley, double-probe electric field experiment. The measurements averaged over the 3-s spin period of the spacecraft provide the first observations of the large-scale (100 km) laminar oscillations in the longitudinal component of the electric field associated with the whistler precursor which is characteristic of these dispersive shocks. The amplitude of the oscillations increases from ∼0.5 mV/m to a maximum of 6 mV/m across the magnetic ramp of the shock (directed along the shock normal). The calculated electric potential drops across the shocks varied from 340 to 550 volts, which is 40-60% of the observed loss of kinetic energy associated with the bulk flow of the ions. These measurements suggest that at these shocks the additional deceleration of incident ions is due to the Lorentz force. The contributions to the normal component of the large-scale electric field at the shock due to the parallel and perpendicular components (relative to the magnetic field) of the electric field are evaluated. It is shown that the perpendicular component of the electric field dominates, accounting for most of the cross-shock potential, but that there is a nonnegligible parallel component. This large-scale parallel component has a magnitude of 1-2 mV/m which sometimes results in a potential well for electrons with a depth of ∼150 eV. It is experimentally demonstrated that the dominance of the perpendicular over the parallel component of the electric field resulted in a correlation between the longitudinal component of the large-scale electric field and the fluctuations in the magnetic field component perpendicular to the coplanarity plane

Adiabatic and non-adiabatic electron oscillations in a static electric field

International Nuclear Information System (INIS)

Wahlberg, C.

1977-03-01

The influence of a static electric field on the oscillations of a one-dimensional stream of electrons is investigated. In the weak field limit the oscillations are adiabatic and mode coupling negligible, but becomes significant if the field is tronger. The latter effect is believed to be of importance for the stability of e.g. potential double layers

A Power-Frequency Electric Field Sensor for Portable Measurement.

Science.gov (United States)

Xiao, Dongping; Ma, Qichao; Xie, Yutong; Zheng, Qi; Zhang, Zhanlong

2018-03-31

In this paper, a new type of electric field sensor is proposed for the health and safety protection of inspection staff in high-voltage environments. Compared with the traditional power frequency electric field measurement instruments, the portable instrument has some special performance requirements and, thus, a new kind of double spherical shell sensor is presented. First, the mathematical relationships between the induced voltage of the sensor, the output voltage of the measurement circuit, and the original electric field in free space are deduced theoretically. These equations show the principle of the proposed sensor to measure the electric field and the effect factors of the measurement. Next, the characteristics of the sensor are analyzed through simulation. The simulation results are in good agreement with the theoretical analysis. The influencing rules of the size and material of the sensor on the measurement results are summarized. Then, the proposed sensor and the matching measurement system are used in a physical experiment. After calibration, the error of the measurement system is discussed. Lastly, the directional characteristic of the proposed sensor is experimentally tested.

Dissimilar kinetic behavior of electrically manipulated single- and double-stranded DNA tethered to a gold surface.

Science.gov (United States)

Rant, Ulrich; Arinaga, Kenji; Tornow, Marc; Kim, Yong Woon; Netz, Roland R; Fujita, Shozo; Yokoyama, Naoki; Abstreiter, Gerhard

2006-05-15

We report on the electrical manipulation of single- and double-stranded oligodeoxynucleotides that are end tethered to gold surfaces in electrolyte solution. The response to alternating repulsive and attractive electric surface fields is studied by time-resolved fluorescence measurements, revealing markedly distinct dynamics for the flexible single-stranded and stiff double-stranded DNA, respectively. Hydrodynamic simulations rationalize this finding and disclose two different kinetic mechanisms: stiff polymers undergo rotation around the anchoring pivot point; flexible polymers, on the other hand, are pulled onto the attracting surface segment by segment.

Numerical simulation of a backward-facing step flow in a microchannel with external electric field

Directory of Open Access Journals (Sweden)

Qing-He Yao

2015-03-01

Full Text Available A backward-facing step flow in the microchannel with external electric field was investigated numerically by a high-order accuracy upwind compact difference scheme in this work. The Poisson–Boltzmann and Navier–Stokes equations were computed by the high-order scheme, and the results confirmed the ability of the new solver in simulation of micro-scale electric double layer effects. The flow fields were displayed for different Reynolds numbers; the positions of the vortex saddle point of model with external electric field and model without external electric field were compared. The average velocity increases linearly with the electric field intensity; however, the Joule heating effects cannot be neglected when the electric field intensity increases to a certain level.

Electric field effect on exchange interaction in ultrathin Co films with ionic liquids

Science.gov (United States)

Ishibashi, Mio; Yamada, Kihiro T.; Shiota, Yoichi; Ando, Fuyuki; Koyama, Tomohiro; Kakizakai, Haruka; Mizuno, Hayato; Miwa, Kazumoto; Ono, Shimpei; Moriyama, Takahiro; Chiba, Daichi; Ono, Teruo

2018-06-01

Electric-field modulations of magnetic properties have been extensively studied not only for practical applications but also for fundamental interest. In this study, we investigated the electric field effect on the exchange interaction in ultrathin Co films with ionic liquids. The exchange coupling J was characterized from the direct magnetization measurement as a function of temperature using Pt/ultrathin Co/MgO structures. The trend of the electric field effect on J is in good agreement with that of the theoretical prediction, and a large change in J by applying a gate voltage was observed by forming an electric double layer using ionic liquids.

Double photoexcitation of helium in a strong dc electric field

International Nuclear Information System (INIS)

Harries, James R.; Sullivan, James P.; Sternberg, James B.; Obara, Satoshi; Suzuki, Tadayuki; Azuma, Yoshiro; Hammond, Peter; Bozek, John; Berrah, Nora; Halka, Monica

2003-01-01

We report the first experimental measurements of the effect of an applied field on the photoexcitation and autoionization of doubly excited states of helium. Ground-state photoionization spectra have been measured in the region below the He + (N=2) threshold with static electric fields of up to 84.4 kV/cm across the interaction region. The results are compared to the theoretical calculations of Chung et al. [J. Phys. B10.1088/0953-4075/34/2/304 34, 165 (2001)], which are the only calculations available in this regime. Transitions to several states in the N=2, n=6 manifold are assigned, and a wealth of new structure is observed. Our data show that many more series are mixed in by the field than those predicted by theory

Double layers above the aurora

International Nuclear Information System (INIS)

Temerin, M.; Mozer, F.S.

1987-01-01

Two different kinds of double layers were found in association with auroral precipitation. One of these is the so-called electrostatic shock, which is oriented at an oblique angle to the magnetic field in such a way that the perpendicular electric field is much larger than the parallel electric field. This type of double layer is often found at the edges of regions of upflowing ion beams and the direction of the electric fields in the shock points toward the ion beam. The potential drop through the shock can be several kV and is comparable to the total potential needed to produce auroral acceleration. Instabilities associated with the shock may generate obliquely propagating Alfven waves, which may accelerate electrons to produce flickering auroras. The flickering aurora provides evidence that the electrostatic shock may have large temporal fluctuations. The other kind of double layer is the small-amplitude double layer found in regions of upward flowing in beams, often in association with electrostatic ion cyclotron waves. The parallel and perpendicular electric fields in these structures are comparable in magnitude. The associated potentials are a few eV. Since many such double layers are found in regions of upward flowing ion beams, the combined potential drop through a set of these double layers can be substantial

Modelling of radial electric field profile for different divertor configurations

International Nuclear Information System (INIS)

Rozhansky, V; Kaveeva, E; Voskoboynikov, S; Counsell, G; Kirk, A; Meyer, H; Coster, D; Conway, G; Schirmer, J; Schneider, R

2006-01-01

The impact of divertor configuration on the structure of the radial electric field has been simulated by the B2SOLPS5.0 transport fluid code. It is shown that the change in the parallel flows in the scrape-off layer, which are transported through the separatrix due to turbulent viscosity and diffusivity, should result in variation of the radial electric field and toroidal rotation in the separatrix vicinity. The modelling predictions are compared with the measurements of the radial electric field for the low field side equatorial mid-plane of ASDEX Upgrade in lower, upper and double-null (DN) divertor configurations. The parallel (toroidal) flows in the scrape-off layer and mechanisms for their formation are analysed for different geometries. It is demonstrated that a spike in the electric field exists at the high field side equatorial mid-plane in the connected DN divertor configuration. Its origin is connected with different potential drops between the separatrix vicinity and divertor plates in the two disconnected scrape-off layers, while the separatrix should be at almost the same potential. The spike might be important for additional turbulent suppression

Nucleation of superconductivity under rapid cycling of an electric field

International Nuclear Information System (INIS)

Bandyopadhyay, Malay

2008-01-01

The effect of an externally applied high-frequency oscillating electric field on the critical nucleation field of superconductivity in the bulk as well as at the surface of a superconductor is investigated in detail in this work. Starting from the linearized time-dependent Ginzburg-Landau (TDLG) theory, and using the variational principle, I have shown the analogy between a quantum harmonic oscillator with that of the nucleation of superconductivity in the bulk and a quantum double oscillator with that of the nucleation at the surface of a finite sample. The effective Hamiltonian approach of Cook et al (1985 Phys. Rev. A 31 564) is employed to incorporate the effect of an externally applied highly oscillating electric field. The critical nucleation field ratio is also calculated from the ground state energy method. The results obtained from these two approximate theories agree very well with the exact results for the case of an undriven system, which establishes the validity of these two approximate theories. It is observed that the highly oscillating electric field actually increases the bulk critical nucleation field (H c 2 ) as well as the surface critical nucleation field (H c 3 ) of superconductivity as compared to the case of absent electric field (ε 0 = 0). But the externally applied rapidly oscillating electric field accentuates the surface critical nucleation field more than the bulk critical nucleation field, i.e. the increase of H c 3 is 1.6592 times larger than that of H c 2

Earth's electric field

International Nuclear Information System (INIS)

Kelley, M.C.

1978-01-01

The earth becomes charged during thunderstorm activity and discharges through the weak conducting atmosphere. Balloon and rocket studies infer that a high altitude electric field penetrates virtually unattenuated through the atmosphere, at least as far as balloon heights. The field has two primary sources. At low and mid latitudes, interaction between the earth's magnetic field and the neutral wind creates electric fields. At latitudes above 60 0 , the high altitude electrical structure is dominated by the interaction between the solar wind and the earth's magnetic field. The auroral light is emitted by atmospheric atoms and molecules excited by electrons with potentials of many thousands volts. The potentials are induced by the solar wind. Recent satellite data shows that the electrons get this energy by passing through a localized electric field about 6000 km above the auroral zone. Several rocket and satellite experiments used to study the earth's electric field are discussed

Plasmasphere and ring current electric fields observed by GEOS 2

International Nuclear Information System (INIS)

Schmidt, R.; Pedersen, A.

1988-01-01

The electric field double probe data from GEOS 2 have been statistically examined to study the consecutive passage of the afternoon plasmaspheric bulge and the trough at the geostationary orbit. It was found that the average location of the bulge depends on the magnetic activity and was encountered at earlier local times for higher magnetospheric activity. Within the bulge the electric field showed very frequently a typical directional change from dawnward outside to duskward inside the bulge. The magnitude of the magnetic field was frequently much smaller near the outbound crossing of the plasmaspheric bulge than is expected from a long-term average. The E x B/B-squared drift pointed azimuthally eastward prior to the encounter of the bulge and rotated into the sunward direction within the bulge. Following its passage through the dense, cold plasma in the bulge, GEOS 2 encountered a hot and tenuous plasma sheet-type plasma in the trough that occasionally corrupted the electric field measurements. Generally, the electric field in the trough is much smaller than in the bulge. A possible cause of the sunward plasma flow within the bulge is discussed on the basis of these data. 13 references

A review of molecular modelling of electric double layer capacitors.

Science.gov (United States)

Burt, Ryan; Birkett, Greg; Zhao, X S

2014-04-14

Electric double-layer capacitors are a family of electrochemical energy storage devices that offer a number of advantages, such as high power density and long cyclability. In recent years, research and development of electric double-layer capacitor technology has been growing rapidly, in response to the increasing demand for energy storage devices from emerging industries, such as hybrid and electric vehicles, renewable energy, and smart grid management. The past few years have witnessed a number of significant research breakthroughs in terms of novel electrodes, new electrolytes, and fabrication of devices, thanks to the discovery of innovative materials (e.g. graphene, carbide-derived carbon, and templated carbon) and the availability of advanced experimental and computational tools. However, some experimental observations could not be clearly understood and interpreted due to limitations of traditional theories, some of which were developed more than one hundred years ago. This has led to significant research efforts in computational simulation and modelling, aimed at developing new theories, or improving the existing ones to help interpret experimental results. This review article provides a summary of research progress in molecular modelling of the physical phenomena taking place in electric double-layer capacitors. An introduction to electric double-layer capacitors and their applications, alongside a brief description of electric double layer theories, is presented first. Second, molecular modelling of ion behaviours of various electrolytes interacting with electrodes under different conditions is reviewed. Finally, key conclusions and outlooks are given. Simulations on comparing electric double-layer structure at planar and porous electrode surfaces under equilibrium conditions have revealed significant structural differences between the two electrode types, and porous electrodes have been shown to store charge more efficiently. Accurate electrolyte and

Resonant cell of a double nuclear electron resonance spectrometer for performance in a 120-350 Gs magnetic field

International Nuclear Information System (INIS)

Baldin, V.I.; Stepanov, A.P.

1976-01-01

Spectrometer double-frequency resonance cell construction of a double nuclear electron resonance for operation in 120-350 Gs magnetic fields is described. The cell has been developed from a special decimeter resonator with a concentrated capacitance. The electric and magnetic components of a high frequency field are efficiently divided in the separator. Therefore, the insertion of a measuring coil and a sample in the maximum of the magnetic component of the field does not practically affect the distribution and parameters of the high-frequency field. The double-frequency resonance cell proposed provides for a higher accuracy of measuring amplifications of the nuclear magnetic resonance signals when there is the overhauzer effect for 120-350 Gs magnetic fields

Analysis of Surface Electric Field Measurements from an Array of Electric Field Mills

Science.gov (United States)

Lucas, G.; Thayer, J. P.; Deierling, W.

2016-12-01

Kennedy Space Center (KSC) has operated an distributed array of over 30 electric field mills over the past 18 years, providing a unique data set of surface electric field measurements over a very long timespan. In addition to the electric field instruments there are many meteorological towers around KSC that monitor the local meteorological conditions. Utilizing these datasets we have investigated and found unique spatial and temporal signatures in the electric field data that are attributed to local meteorological effects and the global electric circuit. The local and global scale influences on the atmospheric electric field will be discussed including the generation of space charge from the ocean surf, local cloud cover, and a local enhancement in the electric field that is seen at sunrise.

Design and construction of a broad-band electric field probe

International Nuclear Information System (INIS)

Bahrami, A.; Sohrabi, M.; Farvadin, D.

1996-01-01

The design of a broad-band electric field probe based on a resistive film diode antenna on RT/Duroid substrate to measure the electric RF/MW fields as constructed at the National Radiation Protection Department (NRPD) of the Atomic Energy Organization of Iran (AEOI) are described in this paper. A square law diode detector with a matching circuit and also low pass filter have been used to produce a dc current proportional to the square RF voltage across the resistive antenna gap. A double-strip coplanar waveguide has also been designed to transfer this dc current to an amplifier with an output signal showing the electric field intensity in one direction. By using three mutually orthogonal resistive antennas, an isotropic electric field probe was made. All parts of this probe have been completely modeled and solved by the MATLAB computer program to determine the optimum values of the elements of the probe. The frequency response of the probe has also been theoretically found to be flat in the range 0.8 to 3 GHz. It was found to be quite satisfactory compared with those of similar probes commercially available. The probe is being used routinely in practice. (author)

Optical properties of an elliptic quantum ring: Eccentricity and electric field effects

Science.gov (United States)

Bejan, Doina; Stan, Cristina; Niculescu, Ecaterina C.

2018-04-01

We have theoretically studied the electronic and optical properties of a GaAs/AlGaAs elliptic quantum ring under in-plane electric field. The effects of an eccentric internal barrier -placed along the electric field direction, chosen as x-axis- and incident light polarization are particularly taken into account. The one-electron energy spectrum and wave functions are found using the adiabatic approximation and the finite element method within the effective-mass model. We show that it is possible to repair the structural distortion by applying an appropriate in-plane electric field, and the compensation is almost complete for all electronic states under study. For both concentric and eccentric quantum ring the intraband optical properties are very sensitive to the electric field and probe laser polarization. As expected, in the systems with eccentricity distortions the energy spectrum, as well as the optical response, strongly depends on the direction of the externally applied electric field, an effect that can be used as a signature of ring eccentricity. We demonstrated the possibility of generating second harmonic response at double resonance condition for incident light polarized along the x-axis if the electric field or/and eccentric barrier break the inversion symmetry. Also, strong third harmonic signal can be generated at triple resonance condition for a specific interval of electric field values when using y-polarized light.

Rocket measurements of electric fields, electron density and temperature during the three phases of auroral substorms

International Nuclear Information System (INIS)

Marklund, G.; Block, L.; Lindqvist, P.-A.

1979-12-01

On Jan. 27, 1979, three rocket payloads were launched from Kiruna, Sweden, into different phases of two successive auroral substorms. Among other experiments, the payloads carried the RIT double probe electric field experiments, providing electric field, electron density and temperature data, which are presented here. These are discussed in association with observations of particles, ionospheric drifts (STARE) and electric fields in the equatorial plane (GEOS). The motions of the auroral forms, as obtained from auroral pictures are compared with the E x B/B 2 drifts and the currents calculated from the rocket electric field and density measurements with the equivalent current system deduced from ground based magnetometer data (SMA). (Auth.)

Application of Electric Double Layer Capacitor for Solar Car

OpenAIRE

中西, 弘一; 岸, 純男; 仲森, 昌也; 荒賀, 浩一

2016-01-01

This paper describes a method for efficient work of electrical energy, using DC-DC converter as insulate between battery and Electrical Double Layer Capacitor (EDLC). In case of constant-current charge to the EDLC, the efficiency of the electric power is higher, compared to the constant-voltage charge.

Tripolar electric field Structure in guide field magnetic reconnection

Science.gov (United States)

Fu, Song; Huang, Shiyong; Zhou, Meng; Ni, Binbin; Deng, Xiaohua

2018-03-01

It has been shown that the guide field substantially modifies the structure of the reconnection layer. For instance, the Hall magnetic and electric fields are distorted in guide field reconnection compared to reconnection without guide fields (i.e., anti-parallel reconnection). In this paper, we performed 2.5-D electromagnetic full particle simulation to study the electric field structures in magnetic reconnection under different initial guide fields (Bg). Once the amplitude of a guide field exceeds 0.3 times the asymptotic magnetic field B0, the traditional bipolar Hall electric field is clearly replaced by a tripolar electric field, which consists of a newly emerged electric field and the bipolar Hall electric field. The newly emerged electric field is a convective electric field about one ion inertial length away from the neutral sheet. It arises from the disappearance of the Hall electric field due to the substantial modification of the magnetic field and electric current by the imposed guide field. The peak magnitude of this new electric field increases linearly with the increment of guide field strength. Possible applications of these results to space observations are also discussed.

Tripolar electric field Structure in guide field magnetic reconnection

Directory of Open Access Journals (Sweden)

S. Fu

2018-03-01

Full Text Available It has been shown that the guide field substantially modifies the structure of the reconnection layer. For instance, the Hall magnetic and electric fields are distorted in guide field reconnection compared to reconnection without guide fields (i.e., anti-parallel reconnection. In this paper, we performed 2.5-D electromagnetic full particle simulation to study the electric field structures in magnetic reconnection under different initial guide fields (Bg. Once the amplitude of a guide field exceeds 0.3 times the asymptotic magnetic field B0, the traditional bipolar Hall electric field is clearly replaced by a tripolar electric field, which consists of a newly emerged electric field and the bipolar Hall electric field. The newly emerged electric field is a convective electric field about one ion inertial length away from the neutral sheet. It arises from the disappearance of the Hall electric field due to the substantial modification of the magnetic field and electric current by the imposed guide field. The peak magnitude of this new electric field increases linearly with the increment of guide field strength. Possible applications of these results to space observations are also discussed.

Enhanced transconductance in a double-gate graphene field-effect transistor

Science.gov (United States)

Hwang, Byeong-Woon; Yeom, Hye-In; Kim, Daewon; Kim, Choong-Ki; Lee, Dongil; Choi, Yang-Kyu

2018-03-01

Multi-gate transistors, such as double-gate, tri-gate and gate-all-around transistors are the most advanced Si transistor structure today. Here, a genuine double-gate transistor with a graphene channel is experimentally demonstrated. The top and bottom gates of the double-gate graphene field-effect transistor (DG GFET) are electrically connected so that the conductivity of the graphene channel can be modulated simultaneously by both the top and bottom gate. A single-gate graphene field-effect transistor (SG GFET) with only the top gate is also fabricated as a control device. For systematical analysis, the transfer characteristics of both GFETs were measured and compared. Whereas the maximum transconductance of the SG GFET was 17.1 μS/μm, that of the DG GFET was 25.7 μS/μm, which is approximately a 50% enhancement. The enhancement of the transconductance was reproduced and comprehensively explained by a physics-based compact model for GFETs. The investigation of the enhanced transfer characteristics of the DG GFET in this work shows the possibility of a multi-gate architecture for high-performance graphene transistor technology.

Bidirectional ionic wind in nonpremixed counterflow flames with DC electric fields

KAUST Repository

Park, Daegeun

2016-05-05

Under an electric field, ions in the reaction zone of a flame generate a bulk flow motion called ionic wind. Because the majority of ions are positive, ionic wind is commonly considered to be unidirectional toward the cathode. A more thorough understanding of the effects of electric fields on flames could be obtained by clarifying the role of minor negative ions in the ionic wind. Here, we report on the effects of direct current on nonpremixed counterflow flames by visualizing the ionic wind. We found that the original flow field separates near the flame when it locates at a flow stagnation plane, resulting in a double-stagnant flow configuration. This evidences a bidirectional ionic wind blowing from the flame to both the cathode and the anode due to the positive and the negative ions, respectively. Meanwhile, an electric body force pulls the flame toward the cathode. Thus, the electric field affects the strain rate and the axial location of the stoichiometry, which are important for characterizing nonpremixed counterflow flames. In addition, measurement of the electric current density roughly showed a nearly saturated current when these flames restabilized under relatively high voltage. Detailed explanations of flame behavior, electric currents, and flow characteristics of various fuels are discussed in this study.

External electric field effect on the binding energy of a hydrogenic donor impurity in InGaAsP/InP concentric double quantum rings

Science.gov (United States)

Hu, Min; Wang, Hailong; Gong, Qian; Wang, Shumin

2018-04-01

Within the framework of effective-mass envelope-function theory, the ground state binding energy of a hydrogenic donor impurity is calculated in the InGaAsP/InP concentric double quantum rings (CDQRs) using the plane wave method. The effects of geometry, impurity position, external electric field and alloy composition on binding energy are considered. It is shown that the peak value of the binding energy appears in two rings with large gap as the donor impurity moves along the radial direction. The binding energy reaches the peak value at the center of ring height when the donor impurity moves along the axial direction. The binding energy shows nonlinear variation with the increase of ring height. With the external electric field applied along the z-axis, the binding energy of the donor impurity located at zi ≥ 0 decreases while that located at zi < 0 increases. In addition, the binding energy decreases with increasing Ga composition, but increases with the increasing As composition.

On the physics of relativistic double layers

International Nuclear Information System (INIS)

Carlqvist, P.

1982-06-01

A model of a strong, time-independent, and relativistic double layer is studied. Besides double layers having the electric field parallel to the current the model also describes a certain type of oblique double layers. The 'Langmuir condition' (ratio of ion current density to electron current density) as well as an expression for the potential drop of the double layer are derived. Furthermore, the distribution of charged particles, electric field, and potential within the double layer are clarified and discussed. It is found that the properties of relativistic double layers differ substantially from the properties of corresponding non-relativistic double layers. (Author)

An electric field in a gravitational field

International Nuclear Information System (INIS)

Harpaz, Amos

2005-01-01

The behaviour of an electric field in a gravitational field is analysed. It is found that due to the mass (energy) of the electric field, it is subjected to gravity and it falls in the gravitational field. This fall curves the electric field, a stress force (a reaction force) is created, and the interaction of this reaction force with the static charge gives rise to the creation of radiation

The topology of Double Field Theory

Science.gov (United States)

Hassler, Falk

2018-04-01

We describe the doubled space of Double Field Theory as a group manifold G with an arbitrary generalized metric. Local information from the latter is not relevant to our discussion and so G only captures the topology of the doubled space. Strong Constraint solutions are maximal isotropic submanifold M in G. We construct them and their Generalized Geometry in Double Field Theory on Group Manifolds. In general, G admits different physical subspace M which are Poisson-Lie T-dual to each other. By studying two examples, we reproduce the topology changes induced by T-duality with non-trivial H-flux which were discussed by Bouwknegt, Evslin and Mathai [1].

DC Electric Field measurement in the Mid-latitude Ionosphere during MSTID by S-520-27 Sounding Rocket Experiments

Science.gov (United States)

Ishisaka, K.; Yamamoto, M.; Yokoyama, T.; Tanaka, M.; Abe, T.; Kumamoto, A.

2015-12-01

In the middle latitude ionospheric F region, mainly in summer, wave structures of electron density that have wave length of 100-200 km and period of one hour are observed. This phenomena is called Medium Scale Traveling Ionosphiric Disturbance; MSTID. MSTID has been observed by GPS receiving network, and its characteristic were studied. In the past, MSTID was thought to be generated by the Perkins instability, but its growth ratio was too small to be effective so far smaller than the real. Recently coupling process between ionospheric E and F regions are studied by using two radars and by computer simulations. Through these studies, we now have hypothesis that MSTID is generated by the combination of E-F region coupling and Perkins instability. The S-520-27 sounding rocket experiment on E-layer and F-layer was planned in order to verify this hypothesis. S-520-27 sounding rocket was launched at 23:57 JST on 20th July, 2013 from JAXA Uchinoura Space Center. S-520-27 sounding rocket reached 316km height. The S-520-27 payload was equipped with Electric Field Detector (EFD) with a two set of orthogonal double probes to measure DC electric field in the spin plane of the payload. The electrodes of two double probe antennas were used to gather the potentials which were detected with high impedance pre-amplifier using the floating (unbiased) double probe technique. As a results of measurements of DC electric fields by the EFD, the natural electric field was about +/-5mV/m, and varied the direction from southeast to east. Then the electric field was mapped to the horizontal plane at 280km height along the geomagnetic field line. In this presentation, we show the detail result of DC electric field measurement by S-520-27 sounding rocket and then we discuss about the correlation between the natural electric field and TEC variation by using the GPS-TEC.

Electric Potential and Electric Field Imaging with Applications

Science.gov (United States)

Generazio, Ed

2016-01-01

The technology and techniques for remote quantitative imaging of electrostatic potentials and electrostatic fields in and around objects and in free space is presented. Electric field imaging (EFI) technology may be applied to characterize intrinsic or existing electric potentials and electric fields, or an externally generated electrostatic field may be used for (illuminating) volumes to be inspected with EFI. The baseline sensor technology, electric field sensor (e-sensor), and its construction, optional electric field generation (quasistatic generator), and current e-sensor enhancements (ephemeral e-sensor) are discussed. Demonstrations for structural, electronic, human, and memory applications are shown. This new EFI capability is demonstrated to reveal characterization of electric charge distribution, creating a new field of study that embraces areas of interest including electrostatic discharge mitigation, crime scene forensics, design and materials selection for advanced sensors, dielectric morphology of structures, inspection of containers, inspection for hidden objects, tether integrity, organic molecular memory, and medical diagnostic and treatment efficacy applications such as cardiac polarization wave propagation and electromyography imaging.

Nonequilibrium electrophoresis of an ion-selective microgranule for weak and moderate external electric fields

Science.gov (United States)

Frants, E. A.; Ganchenko, G. S.; Shelistov, V. S.; Amiroudine, S.; Demekhin, E. A.

2018-02-01

Electrokinetics and the movement of charge-selective micro-granules in an electrolyte solution under the influence of an external electric field are investigated theoretically. Straightforward perturbation analysis is applied to a thin electric double layer and a weak external field, while a numerical solution is used for moderate electric fields. The asymptotic solution enables the determination of the salt concentration, electric charge distribution, and electro-osmotic velocity fields. It may also be used to obtain a simple analytical formula for the electrophoretic velocity in the case of quasi-equilibrium electrophoresis (electrophoresis of the first kind). This formula differs from the famous Helmholtz-Smoluchowski relation, which applies to dielectric microparticles, but not to ion-selective granules. Numerical calculations are used to validate the derived formula for weak external electric fields, but for moderate fields, nonlinear effects lead to a significant increase in electrophoretic mobility and to a transition from quasi-equilibrium electrophoresis of the first kind to nonequilibrium electrophoresis of the second kind. Theoretical results are successfully compared with experimental data.

Saturation of ionization signal in TMP and TMS at different angles and electric fields

International Nuclear Information System (INIS)

Aubert, B.; Colas, J.; Ghez, Ph.; Lacotte, J.C.; Mansoulie, B.; Teiger, J.

1989-09-01

The saturation of ionization signal is measured for various electric fields and incidence angles in a double gap TMP chamber and a single gap TMS chamber with ionizing particles in the range 1.5 - 12 MeV/cm. Birks' constant Kb in TMP is found to be high (greater than 0.1 cm/MeV) for normal incidence for electric fields in the range 4.8 to 12 kV/cm but decreases by almost a factor 3 at 50 0 . The same behaviour (large Kb and variation with incidence angle) is observed in TMS which exhibits also a Kb decrease of about a factor 2 when the electric field is increased from 10 to 40 kV/cm

Aluminum and gallium nuclei as microscopic probes for pulsed electron-nuclear double resonance diagnostics of electric-field gradient and spin density in garnet ceramics doped with paramagnetic ions

Science.gov (United States)

Uspenskaya, Yu. A.; Mamin, G. V.; Babunts, R. A.; Badalyan, A. G.; Edinach, E. V.; Asatryan, H. R.; Romanov, N. G.; Orlinskii, S. B.; Khanin, V. M.; Wieczorek, H.; Ronda, C.; Baranov, P. G.

2018-03-01

The presence of aluminum and gallium isotopes with large nuclear magnetic and quadrupole moments in the nearest environment of impurity ions Mn2+ and Ce3+ in garnets made it possible to use hyperfine and quadrupole interactions with these ions to determine the spatial distribution of the unpaired electron and the gradient of the electric field at the sites of aluminum and gallium in the garnet lattice. High-frequency (94 GHz) electron spin echo detected electron paramagnetic resonance and electron-nuclear double resonance measurements have been performed. Large difference in the electric field gradient and quadrupole splitting at octahedral and tetrahedral sites allowed identifying the positions of aluminum and gallium ions in the garnet lattice and proving that gallium first fills tetrahedral positions in mixed aluminum-gallium garnets. This should be taken into account in the development of garnet-based scintillators and lasers. It is shown that the electric field gradient at aluminum nuclei near Mn2+ possessing an excess negative charge in the garnet lattice is ca. 2.5 times larger than on aluminum nuclei near Ce3+.

Diffuse electric double layer in planar nanostructures due to Fermi-Dirac statistics

International Nuclear Information System (INIS)

Drab, Mitja; Kralj-Iglič, Veronika

2016-01-01

A double nanocapacitor modelled by two equally charged planar surfaces that confine oppositely charged quanta subjected to Fermi-Dirac statistics is considered theoretically. A global thermodynamic equilibrium was found by minimization of the Helmholtz free energy satisfying constraints that require electroneutrality and fixed total number of confined quanta. The solution obtained by using the Euler–Lagrange method yields self–consistent quantities: distribution of quanta within the pore, electric potential, equilibrium free energy and differential capacitance. Within real values, a rigorous numerical solution and an approximate analytical solution for electrons in the low temperature limit was found. The Fermi–Dirac constraints on the wave functions in the nanopore induced an effect of a diffuse electrical double layer near both charged surfaces. This effect is comparable to the corresponding effect of entropy at finite temperatures and for classical particles, as described by the acknowledged Poisson–Boltzmann theory. At small distances and small surface charges, the electrons are almost evenly distributed within the pore, while at larger distances they condense to the charged surfaces, shielding the electric field. The force between the charged surfaces is repulsive and monotonously decreases with increasing distance between surfaces. The energies stored in the nanocapacitor are up to ≃ 50 eV/nm"2.

Electric fields in the magnetosphere

International Nuclear Information System (INIS)

Falthammar, C.G.

1989-01-01

Electric field measurements on the satellites GEOS-1, GEOS-2, ISEE-1, and Viking have extended the empirical knowledge of electric fields in space so as to include the outer regions of the magnetosphere. While the measurements confirm some of the theoretically expected properties of the electric fields, they also reveal unexpected features and a high degree of complexity and variability. The existence of a magnetospheric dawn-to-dusk electric field, as expected on the basis of extrapolation from low altitude measurements, is confirmed in an average sense. However, the actual field exhibits large spatial and temporal variations, including strong fields of inductive origin. At the magnetopause, the average (dawn-to-dusk directed) tangential electric field component is typically obscured by irregular fluctuations of larger amplitude. The magnetic-field aligned component of the electric field, which is of particular importance for ionosphere-magnetosphere coupling and for auroral acceleration, is even now very difficult to measure directly. However, the data from electric field measurements provide further support for the conclusion, based on a variety of evidence, that a non-vanishing magnetic-field aligned electric field exists in the auroral acceleration region

Liquid Crystals of Lithium Dodecylbenzenesulfonate for Electric Double Layer Capacitors

International Nuclear Information System (INIS)

Kuzmin, Andrey Vasil’evich; Yurtov, Evgeny V.

2016-01-01

Ionic lyotropic liquid crystals based on lithium dodecylbenzenesulfonate were used as electrolytes for electric double layer capacitors with carbon fibrous electrodes. The capacitors were tasted by cyclic voltammetry, galvanostatic charge and discharge, and impedance spectroscopy. The highest specific capacitance was achieved for electrical double layer capacitor equipped with ionic lyotropic liquid crystal of lithium dodecylbenzenesulfonate 35 wt% in water. The specific capacitance of capacitor was calculated from galvanostatic discharge curves – 15 F/g of carbon fibrous material

Crystal structural, magnetic and electrical transport properties of CeKFeMoO6 double perovskite

International Nuclear Information System (INIS)

Huo Guoyan; Ren Minghui; Wang Xiaoqing; Zhang Hongrui; Shi Pengfei

2010-01-01

The crystal structural, magnetic and electrical transport properties of double perovskite CeKFeMoO 6 have been investigated. The crystal structure of the compound is assigned to the monoclinic system with space group P2 1 /n and its lattice parameters are a=0.55345(3) nm, b=0.56068(2) nm, c=0.78390(1) nm, β=89.874(2). The divergence between zero-field-cooling and field-cooling M-T curves demonstrates the anisotropic behavior. The Curie temperature measured from C p -T curve is about 340 K. Isothermal magnetization curve shows that the saturation and spontaneous magnetization are 1.90 and 1.43 μ B /f.u. at 300 K, respectively. The electrical behavior of the sample shows a semiconductor. The electrical transport behavior can be described by variable range hopping model. Large magnetoresistance, -0.88 and -0.18, can be observed under low magnetic field, 0.5 T, at low and room temperature, respectively.

The electric double layer put to work : thermal physics at electrochemical interfaces

NARCIS (Netherlands)

Janssen, M.A.

2017-01-01

Where charged electrode surfaces meet fluids that contain mobile ions, so-called electric double layers (EDLs) form to screen the electric surface charge by a diffuse cloud of counterionic charge in the fluid phase. This double layer has been studied for over a century and is of paramount importance

Analysis of gate underlap channel double gate MOS transistor for electrical detection of bio-molecules

Science.gov (United States)

Ajay; Narang, Rakhi; Saxena, Manoj; Gupta, Mridula

2015-12-01

In this paper, an analytical model for gate drain underlap channel Double-Gate Metal-Oxide-Semiconductor Field-Effect Transistor (DG-MOSFET) for label free electrical detection of biomolecules has been proposed. The conformal mapping technique has been used to derive the expressions for surface potential, lateral electric field, energy bands (i.e. conduction and valence band) and threshold voltage (Vth). Subsequently a full drain current model to analyze the sensitivity of the biosensor has been developed. The shift in the threshold voltage and drain current (after the biomolecules interaction with the gate underlap channel region of the MOS transistor) has been used as a sensing metric. All the characteristic trends have been verified through ATLAS (SILVACO) device simulation results.

Chaotic behaviour of an electrical analogue to the mechanical double pendulum

Directory of Open Access Journals (Sweden)

M. P. Hanias

2008-02-01

Full Text Available In this paper the analogy between a mechanical double pendulum and an oscillating electrical system is presented. Instead of using analytic equations, we used the MultiSim circuit simulation environment in order to reproduce and interpret the response of the electrical oscillator. The electrical double pendulum presents a chaotic regime which is studied quantita-tively by means of state space reconstruction. For this purpose the optimal delay time is calculated and the minimum em-bedding dimension is found with the method of False Nearest Neighbors.

Electrical field of electrical appliances versus distance: A preliminary analysis

International Nuclear Information System (INIS)

Mustafa, Nur Badariah Ahmad; Nordin, Farah Hani; Ismail, Fakaruddin Ali Ahmad; Alkahtani, Ammar Ahmed; Balasubramaniam, Nagaletchumi; Hock, Goh Chin; Shariff, Z A M

2013-01-01

Every household electrical appliance that is plugged in emits electric field even if it is not operating. The source where the appliance is plugged into and the components of household electrical appliance contribute to electric field emission. The electric field may cause unknown disturbance to the environment or also affect the human health and the effect might depends on the strength of the electric field emitted by the appliance. This paper will investigate the strength of the electric field emitted by four different electrical appliances using spectrum analyser. The strength will be captured at three different distances; (i) 1m (ii) 2m and (iii) 3m and analysis of the strength of the electrical field is done based on the three different distances. The measurement results show that the strength of the electric field is strongest when it is captured at 1m and the weakest at 3m from the electrical appliance. The results proved that the farther an object is located from the electrical appliance; the less effect the magnetic field has.

Do Capacity Coupled Electric Fields Accelerate Tibial Stress Fracture Healing

Science.gov (United States)

2006-12-01

MRI confirmed a large coexisting haemangioma which may have confounded perception of stress fracture symptoms. Table 1 is a comprehensive subject...Johnson JR, Light KI, Yuan HA: A double-blind study of capacitively coupled electrical stimulation as an adjunct to lumbar spinal fusions. Spine 24...Simmons JW, Jr., Mooney V, Thacker I: Pseudarthrosis after lumbar spine fusion: nonoperative salvage with pulsed electromagnetic fields. Am J

Pulsed electric fields

Science.gov (United States)

The concept of pulsed electric fields (PEF) was first proposed in 1967 to change the behavior or microorganisms. The electric field phenomenon was identified as membrane rupture theory in the 1980s. Increasing the membrane permeability led to the application of PEF assisted extraction of cellular co...

Electroresistance Effect in Gold Thin Film Induced by Ionic-Liquid-Gated Electric Double Layer

NARCIS (Netherlands)

Nakayama, Hiroyasu; Ye, Jianting; Ohtani, Takashi; Fujikawa, Yasunori; Ando, Kazuya; Iwasa, Yoshihiro; Saitoh, Eiji

Electroresistance effect was detected in a metallic thin film using ionic-liquid-gated electric-double-layer transistors (EDLTs). We observed reversible modulation of the electric resistance of a Au thin film. In this system, we found that an electric double layer works as a nanogap capacitor with

Quasi-static electric field in a cylindrical volume conductor induced by external coils.

Science.gov (United States)

Esselle, K P; Stuchly, M A

1994-02-01

An expansion technique based on modified Bessel functions is used to obtain an analytical solution for the electric field induced in a homogeneous cylindrical volume conductor by an external coil. The current in the coil is assumed to be changing slowly so that quasi-static conditions can be justified. Valid for any coil type, this solution is ideal for fast computation of the induced electric field at a large number of points. Efficient implementation of this method in a computer code is described and numerical results are presented for a perpendicular circular coil and a tangential double-square coil.

Double anisotropic electrically conductive flexible Janus-typed membranes.

Science.gov (United States)

Li, Xiaobing; Ma, Qianli; Tian, Jiao; Xi, Xue; Li, Dan; Dong, Xiangting; Yu, Wensheng; Wang, Xinlu; Wang, Jinxian; Liu, Guixia

2017-12-07

Novel type III anisotropic conductive films (ACFs), namely flexible Janus-typed membranes, were proposed, designed and fabricated for the first time. Flexible Janus-typed membranes composed of ordered Janus nanobelts were constructed by electrospinning, which simultaneously possess fluorescence and double electrically conductive anisotropy. For the fabrication of the Janus-typed membrane, Janus nanobelts comprising a conductive side and an insulative-fluorescent side were primarily fabricated, and then the Janus nanobelts are arranged into parallel arrays using an aluminum rotary drum as the collector to obtain a single anisotropically conductive film. Subsequently, a secondary electrospinning process was applied to the as-prepared single anisotropically conductive films to acquire the final Janus-typed membrane. For this Janus-typed membrane, namely its left-to-right structure, anisotropic electrical conduction synchronously exists on both sides, and furthermore, the two electrically conductive directions are perpendicular. By modulating the amount of Eu(BA) 3 phen complex and conducting polyaniline (PANI), the characteristics and intensity of the fluorescence-electricity dual-function in the membrane can be tuned. The high integration of this peculiar Janus-typed membrane with simultaneous double electrically conductive anisotropy-fluorescent dual-functionality is successfully realized in this study. This design philosophy and preparative technique will provide support for the design and construction of new types of special nanostructures with multi-functionality.

Combined effects of hydrostatic pressure and electric field on the donor binding energy and polarizability in laterally coupled double InAs/GaAs quantum-well wires

International Nuclear Information System (INIS)

Tangarife, E.; Duque, C.A.

2010-01-01

This work is concerned with the theoretical study of the combined effects of applied electric field and hydrostatic pressure on the binding energy and impurity polarizability of a donor impurity in laterally coupled double InAs/GaAs quantum-well wires. calculations have been made in the effective mass and parabolic band approximations and using a variational method. The results are reported for different configurations of wire and barriers widths, impurity position, and electric field and hydrostatic pressure strengths. Our results show that for symmetrical structures the binding energy is an even function of the impurity position along the growth direction of the structure. Also, we found that for hydrostatic pressure strength up to 38 kbar, the binding energy increases linearly with hydrostatic pressure, while for larger values of hydrostatic pressure the binding energy has a nonlinear behavior. Finally, we found that the hydrostatic pressure can increase the coupling between the two parallel quantum well wires.

Ionization measurement as a function of the electric field in tetramethyl-silane (TMS)

International Nuclear Information System (INIS)

Daba, A.G.

1992-07-01

The WALIC collaboration has built a calorimeter prototype using the tetramethyl-pentane (TMP) as active medium and lead as absorber medium in order to study the response of electrons and hadrons. The aim of this work is to study the response of tetramethyl-silane to high electric fields knowing that TMP and TMS have similar properties and similar behaviour with electric field. A test bench is mounted to measure the charge deposited by electrons emitted by a ruthenium source. The trigger was made using a silicon detector. Low noise amplifiers were designed and built for the signal conditioning and in order to reduce the pick-up noise, the system is completely isolated in a double Faraday cage. A theoretical study of noise has been developed. The signal allowed to study the behaviour of warm liquid in presence of a high electric field

In situ electron holography of electric potentials inside a solid-state electrolyte: Effect of electric-field leakage

Energy Technology Data Exchange (ETDEWEB)

Aizawa, Yuka; Yamamoto, Kazuo; Sato, Takeshi [Nanostructures Research Laboratory, Japan Fine Ceramics Center, 2-4-1 Mutsuno, Atsuta-ku, Nagoya, Aichi 456-8587 (Japan); Murata, Hidekazu [Faculty of Science and Technology, Meijo University, 1-501 Shiogamaguchi, Tempaku-ku, Nagoya, Aichi 468-8502 (Japan); Yoshida, Ryuji; Fisher, Craig A.J. [Nanostructures Research Laboratory, Japan Fine Ceramics Center, 2-4-1 Mutsuno, Atsuta-ku, Nagoya, Aichi 456-8587 (Japan); Kato, Takehisa; Iriyama, Yasutoshi [Department of Materials, Physics and Energy Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi 464-8601 (Japan); Hirayama, Tsukasa, E-mail: t-hirayama@jfcc.or.jp [Nanostructures Research Laboratory, Japan Fine Ceramics Center, 2-4-1 Mutsuno, Atsuta-ku, Nagoya, Aichi 456-8587 (Japan)

2017-07-15

In situ electron holography is used to observe changes of electric-potential distributions in an amorphous lithium phosphorus oxynitride (LiPON) solid-state electrolyte when different voltages are applied. 2D phase images are simulated by integrating the 3D potential distribution along the electron trajectory through a thin Cu/LiPON/Cu region. Good agreement between experimental and simulated phase distributions is obtained when the influence of the external electric field is taken into account using the 3D boundary-charge method. Based on the precise potential changes, the lithium-ion and lithium-vacancy distributions inside the LiPON layer and electric double layers (EDLs) are inferred. The gradients of the phase drops at the interfaces in relation to EDL widths are discussed. - Highlights: • Solid-state electrolyte LiPON has been observed by in situ electron holography. • Observed phase distributions are compared with those simulated numerically. • 3D electric fields around the specimen are taken into account in the simulation. • Electric-potential distributions inside LiPON have been obtained. • The lithium-ion and lithium-vacancy distributions inside the LiPON are inferred.

Electric fields and electrical insulation

DEFF Research Database (Denmark)

McAllister, Iain Wilson

2002-01-01

The adoption of a field-theoretical approach to problems arising in the framework of electrical insulation is discussed with reference to six main topics, which have been addressed over the last 30 years. These include uniform field electrodes, Green's differential equation, electrode surface...... roughness, induced charge, electrostatic probes, and partial discharge transients, together with several follow-on aspects. Each topic is introduced and thereafter the progress achieved through the use of a field-theoretical approach is reviewed. Because the topics cover a wide spectrum of conditions......, it is amply demonstrated that such an approach can lead to significant progress in many areas of electrical insulation....

Quasi-static electric fields, turbulence and VLF waves in the ionosphere and magnetosphere

International Nuclear Information System (INIS)

Temerin, M.A.

1978-01-01

Two rocket payloads launched from Greenland in December 1974 and January 1975 into the dayside auroral oval measured large scale electric fields. Sunward convection in regions of polar cusp type particle precipitation argues for the existence of a turbulent entry region at the magnetopause. Smaller scale changes in the electric field and energetic electron precipitation require field-aligned currents predominately at the boundaries of auroral arcs. Measurements of electric fields parallel to the magnetic field place upper limits to the parallel electric field. An analysis of the effect of zero-frequency electric field turbulence on the output of an electric field double probe detector is applied to data from two satellites, OVI-17 and S3-3. It is found that the electric field of high latitude low frequency turbulence is polarized perpendicular to the magnetic field and that the frequency is measured by the satellites is due to the Doppler shift of near zero frequency turbulence both in the ionosphere and magnetosphere. In addition, rocket measurements of low frequency turbulence in the dayside auroral oval reveal characteristics similar to those of the large electric field regions recently seen on S3-3 indicating that the turbulence from those regions extends into the ionosphere. VLF waves were also observed during the two rocket flights into the dayside auroral oval. The correlation of the VLF hiss intensity with the fluxes of precipitating electrons above 500 eV on a short spatial and time scale is often poor, even when a positive slope exists in the electron phase space density. The frequency of the lower hybrid waves were used to measure the ratio of NO + and O 2 + to O + . Electrostatic waves were observed during a barium release

Towards weakly constrained double field theory

Directory of Open Access Journals (Sweden)

Kanghoon Lee

2016-08-01

Full Text Available We show that it is possible to construct a well-defined effective field theory incorporating string winding modes without using strong constraint in double field theory. We show that X-ray (Radon transform on a torus is well-suited for describing weakly constrained double fields, and any weakly constrained fields are represented as a sum of strongly constrained fields. Using inverse X-ray transform we define a novel binary operation which is compatible with the level matching constraint. Based on this formalism, we construct a consistent gauge transform and gauge invariant action without using strong constraint. We then discuss the relation of our result to the closed string field theory. Our construction suggests that there exists an effective field theory description for massless sector of closed string field theory on a torus in an associative truncation.

Transitionless Enhanced Confinement and the Role of Radial Electric Field Shear

International Nuclear Information System (INIS)

Coppi, B.; Ernst, D.R.; Bell, M.G.; Bell, R.E.; Budny, R.V.

1999-01-01

Evidence for the role of radial electric field shear in enhanced confinement regimes attained without sharp bifurcations or transitions is presented. Temperature scans at constant density, created in the reheat phase following deuterium pellet injection into supershot plasmas in the Tokamak Fusion Test Reactor [J.D. Strachan, et al., Phys. Rev. Lett. 58 (1987) 1004] are simulated using a first-principles transport model. The slow reheat of the ion temperature profile, during which the temperature nearly doubles, is not explained by relatively comprehensive models of transport due to Ion Temperature Gradient Driven Turbulence (ITGDT), which depends primarily on the (unchanging) electron density gradient. An extended model, including the suppression of toroidal ITGDT by self-consistent radial electric field shear, does reproduce the reheat phase

Development of a 3 kW double-acting thermoacoustic Stirling electric generator

International Nuclear Information System (INIS)

Wu, Zhanghua; Yu, Guoyao; Zhang, Limin; Dai, Wei; Luo, Ercang

2014-01-01

Highlights: • A 3 kW double-acting thermoacoustic Stirling electric generator is introduced. • 1.57 kW electric power with 16.8% thermal-to-electric efficiency was achieved. • High mechanical damping coefficient greatly decreases the system performance. • Performance difference is significant, which also decreased system performance. - Abstract: In this paper, a double-acting thermoacoustic Stirling electric generator is proposed as a new device capable of converting external heat into electric power. In the system, at least three thermoacoustic Stirling heat engines and three linear alternators are used to build a multiple-cylinder electricity generator. In comparison with the conventional thermoacoustic electricity generation system, the double-acting thermoacoustic Stirling electric generator has advantages on efficiency, power density and power capacity. In order to verify the idea, a prototype of 3 kW three-cylinder double-acting thermoacoustic Stirling electric generator is designed, built and tested. Based on the classic thermoacoustic theory, numerical simulation is performed to obtain the thermodynamic parameters of the engine. And distributions of key parameters are presented for a better understanding of the energy conversion process in the engine. In the experiments, a maximum electric power of about 1.57 kW and a maximum thermal-to-electric conversion efficiency of 16.8% were achieved with 5 MPa pressurized helium and 86 Hz working frequency. However, we find that the mechanical damping coefficient of the piston is dramatically increased due to the deformation of the cylinder wall caused by high thermal stress during the experiments. Thereby, the system performance was greatly reduced. Additionally, the performance differences between three engines and three alternators are significant, such as the heating temperature difference between three heater blocks of the engines, the piston displacement and the output electric power differences between

Exhibition of electric and magnetic fields of extra-low frequency

International Nuclear Information System (INIS)

Rincon, Leonardo; Socadagui, Jorge; Roman, Francisco

2001-01-01

The existent norms were studied in the international environment regarding human beings' exhibition to electro-magnetic fields, under the points of view of the industrial frequency (60 Hz) and the time of exhibition. The norm CENELEC was selected (Committee Europeen of Normalisation Electro technique) ENV 50166-1. The electro-magnetic fields existent were measured in four substations of the Colombian interconnected system, locating the critical fields and relation them with the work places from the personnel exposed to this fields. In different areas of the substations studied they were values of electric field that violate the norm CENELEC, being the most critical case the areas of the module of line and of the patios of transformation. In magnetic field not it founded any violation of the mentioned norm. A serious case of exposed population was identified that corresponds to the gang in charge of carrying out the basic maintenance. This gang carries out its maintenance works in areas with critical electric fields and during superior times of exhibition to those permitted for the norm. The fields electrician and magnetic too were measured under the vain of transmission line of 115 kw and double vertical circuit. The measured values were compared with the values theoretical ob had by means of programs of calculation of fields electric and magnetic developed in the national university of Colombia, being obtained a very good approach for the case of the magnetic field. Using electro-magnetic field well known and trusts procedures, the measure probes were gauged in the laboratory of high voltage of the national university of Colombia

Pure Electric and Pure Magnetic Resonances in Near-Infrared Metal Double-Triangle Metamaterial Arrays

International Nuclear Information System (INIS)

Cao Zhi-Shen; Pan Jian; Chen Zhuo; Zhan Peng; Min Nai-Ben; Wang Zhen-Lin

2011-01-01

We experimentally and numerically investigate the optical properties of metamaterial arrays composed of double partially-overlapped metallic nanotriangles fabricated by an angle-resolved nanosphere lithography. We demonstrate that each double-triangle can be viewed as an artificial magnetic element analogous to the conventional metal split-ring-resonator. It is shown that under normal-incidence conditions, individual double-triangle can exhibit a strong local magnetic resonance, but the collective response of the metamaterial arrays is purely electric because magnetic resonances of the two double-triangles in a unit cell having opposite openings are out of phase. For oblique incidences the metamaterial arrays are shown to support a pure magnetic response at the same frequency band. Therefore, switchable electric and magnetic resonances are achieved in double-triangle arrays. Moreover, both the electric and magnetic resonances are shown to allow for a tunability over a large spectral range down to near-infrared. (condensed matter: electronic structure, electrical, magnetic, and optical properties)

Cryosurgery with Pulsed Electric Fields

Science.gov (United States)

Daniels, Charlotte S.; Rubinsky, Boris

2011-01-01

This study explores the hypothesis that combining the minimally invasive surgical techniques of cryosurgery and pulsed electric fields will eliminate some of the major disadvantages of these techniques while retaining their advantages. Cryosurgery, tissue ablation by freezing, is a well-established minimally invasive surgical technique. One disadvantage of cryosurgery concerns the mechanism of cell death; cells at high subzero temperature on the outer rim of the frozen lesion can survive. Pulsed electric fields (PEF) are another minimally invasive surgical technique in which high strength and very rapid electric pulses are delivered across cells to permeabilize the cell membrane for applications such as gene delivery, electrochemotherapy and irreversible electroporation. The very short time scale of the electric pulses is disadvantageous because it does not facilitate real time control over the procedure. We hypothesize that applying the electric pulses during the cryosurgical procedure in such a way that the electric field vector is parallel to the heat flux vector will have the effect of confining the electric fields to the frozen/cold region of tissue, thereby ablating the cells that survive freezing while facilitating controlled use of the PEF in the cold confined region. A finite element analysis of the electric field and heat conduction equations during simultaneous tissue treatment with cryosurgery and PEF (cryosurgery/PEF) was used to study the effect of tissue freezing on electric fields. The study yielded motivating results. Because of decreased electrical conductivity in the frozen/cooled tissue, it experienced temperature induced magnified electric fields in comparison to PEF delivered to the unfrozen tissue control. This suggests that freezing/cooling confines and magnifies the electric fields to those regions; a targeting capability unattainable in traditional PEF. This analysis shows how temperature induced magnified and focused PEFs could be used to

Cryosurgery with pulsed electric fields.

Directory of Open Access Journals (Sweden)

Charlotte S Daniels

Full Text Available This study explores the hypothesis that combining the minimally invasive surgical techniques of cryosurgery and pulsed electric fields will eliminate some of the major disadvantages of these techniques while retaining their advantages. Cryosurgery, tissue ablation by freezing, is a well-established minimally invasive surgical technique. One disadvantage of cryosurgery concerns the mechanism of cell death; cells at high subzero temperature on the outer rim of the frozen lesion can survive. Pulsed electric fields (PEF are another minimally invasive surgical technique in which high strength and very rapid electric pulses are delivered across cells to permeabilize the cell membrane for applications such as gene delivery, electrochemotherapy and irreversible electroporation. The very short time scale of the electric pulses is disadvantageous because it does not facilitate real time control over the procedure. We hypothesize that applying the electric pulses during the cryosurgical procedure in such a way that the electric field vector is parallel to the heat flux vector will have the effect of confining the electric fields to the frozen/cold region of tissue, thereby ablating the cells that survive freezing while facilitating controlled use of the PEF in the cold confined region. A finite element analysis of the electric field and heat conduction equations during simultaneous tissue treatment with cryosurgery and PEF (cryosurgery/PEF was used to study the effect of tissue freezing on electric fields. The study yielded motivating results. Because of decreased electrical conductivity in the frozen/cooled tissue, it experienced temperature induced magnified electric fields in comparison to PEF delivered to the unfrozen tissue control. This suggests that freezing/cooling confines and magnifies the electric fields to those regions; a targeting capability unattainable in traditional PEF. This analysis shows how temperature induced magnified and focused

Auroral arc classification scheme based on the observed arc-associated electric field pattern

International Nuclear Information System (INIS)

Marklund, G.

1983-06-01

Radar and rocket electric field observations of auroral arcs have earlier been used to identify essentially four different arc types, namely anticorrelation and correlation arcs (with, respectively, decreased and increased arc-assocaited field) and asymmetric and reversal arcs. In this paper rocket double probe and supplementary observations from the literature, obtained under various geophysical conditions, are used to organize the different arc types on a physical rather than morphological basis. This classification is based on the relative influence on the arc electric field pattern from the two current continuity mechanisms, polarisation electric fields and Birkeland currents. In this context the tangential electric field plays an essential role and it is thus important that it can be obtained with both high accuracy and resolution. In situ observations by sounding rockets are shown to be better suited for this specific task than monostatic radar observations. Depending on the dominating mechanism, estimated quantitatively for a number of arc-crossings, the different arc types have been grouped into the following main categories: Polarisation arcs, Birkeland current arcs and combination arcs. Finally the high altitude potential distributions corresponding to some of the different arc types are presented. (author)

Electric fields in the magnetosphere

International Nuclear Information System (INIS)

Faelthammar, C.G.

1989-12-01

The electric field plays an important role in the complex plasma system called the magnetosphere. In spite of this, direct measurement of this quantity are still scarce except in its lowest-altitude part, i.e. the ionosphere. The large scale ionospheric electric field has been determined from measurement on the ground and in low satellite orbit. For most of the magnetosphere, our concepts of the electric field have mostly been based on theoretical considerations and extrapolations of the ionspheric electric field. Direct, in situ, electric field measurements in the outer parts of the magnetosphere have been made only relatively recently. A few satellite missions. most recently the Viking mission, have extended the direct empirical knowledge so as to include major parts of the magnetosphere. These measurements have revealed a number of unexpected features. The actual electric field has been found to have unexpectedly strong space and time variations, which reflect the dynamic nature of the system. Examples are give of measured electric fields in the plasmasphere, the plasmasheet, the neutral sheet, the magnetotail, the flanks of the magnetosphere, the dayside magnetopause and the auroral acceleration region. (author)

Dielectrics in electric fields

CERN Document Server

Raju, Gorur G

2003-01-01

Discover nontraditional applications of dielectric studies in this exceptionally crafted field reference or text for seniors and graduate students in power engineering tracks. This text contains more than 800 display equations and discusses polarization phenomena in dielectrics, the complex dielectric constant in an alternating electric field, dielectric relaxation and interfacial polarization, the measurement of absorption and desorption currents in time domains, and high field conduction phenomena. Dielectrics in Electric Fields is an interdisciplinary reference and text for professionals and students in electrical and electronics, chemical, biochemical, and environmental engineering; physical, surface, and colloid chemistry; materials science; and chemical physics.

Controlling translational motion of neutral molecules in inhomogeneous electric fields

International Nuclear Information System (INIS)

Yamakita, Yoshihiro

2006-01-01

Hydrogen molecules are excited to Rydberg states with n=16, 17 in the presence of inhomogeneous field of an electric dipole by a vacuum ultraviolet-ultraviolet double resonance scheme. The large dipole moment produced in Stark eigenstates leads to strong forces on the molecules in the inhomogeneous electric field. Deflection and deceleration are demonstrated for a pulsed supersonic beam containing the H 2 molecules in the n=16, 17, N + =2, M J =0 Rydberg states. The Rydberg states are found to survive for over 100 μs after the dipole field is switched off. The Rydberg states have a special stability with respect to decay by predissociation. Complete deceleration to the zero mean velocity is numerically demonstrated for H 2 molecules in the higher linear low-field-seeking n=16, M J =0 Rydberg states by using a symplectic integrator of the fourth order. The calculations show that the initial velocity of 900 ms -1 with translational temperature 1 K is decelerated to 0 ms -1 with 13 mK. (author)

An analytical model for the vertical electric field distribution and optimization of high voltage REBULF LDMOS

International Nuclear Information System (INIS)

Hu Xia-Rong; Lü Rui

2014-01-01

In this paper, an analytical model for the vertical electric field distribution and optimization of a high voltage-reduced bulk field (REBULF) lateral double-diffused metal—oxide-semiconductor (LDMOS) transistor is presented. The dependences of the breakdown voltage on the buried n-layer depth, thickness, and doping concentration are discussed in detail. The REBULF criterion and the optimal vertical electric field distribution condition are derived on the basis of the optimization of the electric field distribution. The breakdown voltage of the REBULF LDMOS transistor is always higher than that of a single reduced surface field (RESURF) LDMOS transistor, and both analytical and numerical results show that it is better to make a thick n-layer buried deep into the p-substrate. (interdisciplinary physics and related areas of science and technology)

Development of energy storage system for DC electric rolling stock applying electric double layer capacitor

Energy Technology Data Exchange (ETDEWEB)

Sekijima, Y.; Kudo, Y.; Inui, M. [Central Japan Railway Co., Aichi (Japan); Monden, Y.; Toda, S.; Aoyama, I. [Toshiba Corp., Tokyo (Japan)

2006-07-01

This paper provided details of an energy storage system designed for use with DC electric rolling stock through the application of an electric double layer capacitor (EDLC). The EDLC was selected due to its long life-span and its low operational costs. Testing was conducted to assess the system's basic control function, acceleration using stored energy, and behaviour during regenerative brake failure. A control circuit chip was used in the DC electric rolling stock on an inverter of the energy storage system. Tests confirmed that the control method was effective for actual rolling stocks. A full-scale energy storage system for installation on series 313 locomotives was then constructed. Braking energy was generated only from a regenerative brake. In case of brake failure, braking energy was generated from an air brake was well as an electric brake. Data from a field test conducted at the Tokaido and Chuo railway lines showed a capacity of 0.6 kWh. The EDLC was used to reduce peak air brake energy. It was concluded that storing 0.28 kW of brake energy in the EDLC can reduce peaks of air brake energy in high speed ranges. Experimental equipment was used to confirm use of the system with 0.56 kWh of EDLC, the average energy of air brake used in regenerative energy failure. 1 tab., 10 figs.

Influence of the oscillating electric field on the photodetachment of H− ion in a static electric field

International Nuclear Information System (INIS)

Wang, De-hua

2017-01-01

Highlights: • The photodetachment of H − in an oscillating electric field has been studied using the time-dependent closed orbit theory. • An analytical formula for calculating the photodetachement cross section has been put forward. • Our study provides a clear physical picture for the photodetachment of negative ion in an oscillating electric filed. • Our work is useful in guiding the experimental research for the photodetachment dynamics in the time-dependent field. - Abstract: Using the time-dependent closed orbit theory, we study the photodetachment of H − ion in a time-dependent electric field. The photodetachment cross section is specifically studied in the presence of a static electric field plus an oscillating electric field. We find that the photodetachment of negative ion in the time-dependent electric field becomes much more complicated than the case in a static electric field. The oscillating electric field can weaken the photodetachment cross section greatly when the strength of the oscillating electric field is less than the static electric field. However, as the strength of the oscillating electric field is larger than the static electric field, four types of closed orbits are identified for the detached electron, which makes the oscillating amplitude in the photodetachment cross section gets increased again. The connection between the detached electron’s closed orbit with the oscillating cross section is analyzed quantitatively. This study provides a clear and intuitive picture for the understanding of the connections between quantum and classical description for the time-dependent Hamiltonian systems and may guide the future experimental research for the photodetachment dynamics in the time-dependent electric field.

Electric-field modulation of ferromagnetism in hexagonal chromium telluride thin film

International Nuclear Information System (INIS)

Akiyama, Ryota; Oikawa, Haruyoshi; Yamawaki, Kazuma; Kuroda, Shinji

2014-01-01

We report the electric-field modulation of magnetism of a hexagonal Cr 1-δ Te thin film. A gate voltage V G is ap-plied in the field effect capacitor (FEC) structure consisting of electric double-layer capacitor (EDLC) of an ion liquid and a 2nm-thick Cr 1-δ Te layer grown by molecular beam epitaxy (MBE) and the magnetization of the layer is directly measured using a superconducting quantum interference device (SQUID) magnetometer in the both configurations with magnetic fields perpendicular or parallel to the film plane. As a result, we observe a clear change in the magnetization vs. magnetic field (M-H) curves by applying VG at a low temperature of 15 K in the perpendicular field configuration; the magnetization increases and the coercivity decreases by applying either positive or negative gate voltage. When the temperature is increased up to 160K, slightly lower than the Curie temperature, or the magnetization was measured in the in-plane field configuration, the magnetization increases similarly by applying either positive or negative gate voltage, but the amount of the increase becomes much smaller. A possible mechanism of the electric-field modulation is discussed in relation to the Cr vacancies in the Cr 1-δ Te layer. (copyright 2014 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

Electric-field modulation of ferromagnetism in hexagonal chromium telluride thin film

Energy Technology Data Exchange (ETDEWEB)

Akiyama, Ryota; Oikawa, Haruyoshi; Yamawaki, Kazuma; Kuroda, Shinji [Institute of Materials Science, University of Tsukuba, 1-1-1 Tennoudai, Tsukuba, Ibaraki 305-8573 (Japan)

2014-07-15

We report the electric-field modulation of magnetism of a hexagonal Cr{sub 1-δ}Te thin film. A gate voltage V{sub G} is ap-plied in the field effect capacitor (FEC) structure consisting of electric double-layer capacitor (EDLC) of an ion liquid and a 2nm-thick Cr{sub 1-δ}Te layer grown by molecular beam epitaxy (MBE) and the magnetization of the layer is directly measured using a superconducting quantum interference device (SQUID) magnetometer in the both configurations with magnetic fields perpendicular or parallel to the film plane. As a result, we observe a clear change in the magnetization vs. magnetic field (M-H) curves by applying VG at a low temperature of 15 K in the perpendicular field configuration; the magnetization increases and the coercivity decreases by applying either positive or negative gate voltage. When the temperature is increased up to 160K, slightly lower than the Curie temperature, or the magnetization was measured in the in-plane field configuration, the magnetization increases similarly by applying either positive or negative gate voltage, but the amount of the increase becomes much smaller. A possible mechanism of the electric-field modulation is discussed in relation to the Cr vacancies in the Cr{sub 1-δ}Te layer. (copyright 2014 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

Magnetospheric Multiscale Satellites Observations of Parallel Electric Fields Associated with Magnetic Reconnection

Science.gov (United States)

Ergun, R. E.; Goodrich, K. A.; Wilder, F. D.; Holmes, J. C.; Stawarz, J. E.; Eriksson, S.; Sturner, A. P.; Malaspina, D. M.; Usanova, M. E.; Torbert, R. B.; Lindqvist, P.-A.; Khotyaintsev, Y.; Burch, J. L.; Strangeway, R. J.; Russell, C. T.; Pollock, C. J.; Giles, B. L.; Hesse, M.; Chen, L. J.; Lapenta, G.; Goldman, M. V.; Newman, D. L.; Schwartz, S. J.; Eastwood, J. P.; Phan, T. D.; Mozer, F. S.; Drake, J.; Shay, M. A.; Cassak, P. A.; Nakamura, R.; Marklund, G.

2016-06-01

We report observations from the Magnetospheric Multiscale satellites of parallel electric fields (E∥ ) associated with magnetic reconnection in the subsolar region of the Earth's magnetopause. E∥ events near the electron diffusion region have amplitudes on the order of 100 mV /m , which are significantly larger than those predicted for an antiparallel reconnection electric field. This Letter addresses specific types of E∥ events, which appear as large-amplitude, near unipolar spikes that are associated with tangled, reconnected magnetic fields. These E∥ events are primarily in or near a current layer near the separatrix and are interpreted to be double layers that may be responsible for secondary reconnection in tangled magnetic fields or flux ropes. These results are telling of the three-dimensional nature of magnetopause reconnection and indicate that magnetopause reconnection may be often patchy and/or drive turbulence along the separatrix that results in flux ropes and/or tangled magnetic fields.

Toroidal electric field in front of the lower hybrid grill of the castor tokamak

International Nuclear Information System (INIS)

Zacek, F.; Petrzilka, V.; Devynck, P.; Goniche, M.

2003-01-01

A small tokamak Castor (R/a = 0.4/0.85 m) with low plasma energy density and short pulses (20 ms) offers a unique possibility to carry out probe measurements in front of the grill antenna and as a consequence to provide direct information about the local electric fields in this region. For measurements of the toroidal electrical field, a small double probe with 2 tips separated by 3.5 mm in the toroidal direction has been used. The tips are oriented in the radial direction. The probe is radially movable in front of the central grill waveguide. Cross-correlations and FFT (fast Fourier transform) analysis of the measured V fl signals are given together with an attempt to investigate characteristics of toroidal electric field E tor (up to 500 kHz), derived from V fl measured by 2 toroidally separated tips

Detection of internal fields in double-metal terahertz resonators

DEFF Research Database (Denmark)

Mitrofanov, Oleg; Han, Zhanghua; Ding, Fei

2017-01-01

Terahertz (THz) double-metal plasmonic resonators enable enhanced light-matter coupling by exploiting strong field confinement. The double-metal design however restricts access to the internal fields. We propose and demonstrate a method for spatial mapping and spectroscopic analysis of the internal...... electromagnetic fields in double-metal plasmonic resonators. We use the concept of image charges and aperture-type scanning near-field THz time-domain microscopy to probe the fields confined within the closed resonator. The experimental method opens doors to studies of light-matter coupling in deeply sub...

Studies on electrical double layer capacitor with a low-viscosity ionic ...

Indian Academy of Sciences (India)

The performance of an electrical double layer capacitor (EDLC) composed of high surface area acti- vated carbon ... Since the electric energy stored in EDLCs are raised by the ..... capacitance value, observed by us with the present system, is.

Electric Field Fluctuations in Water

Science.gov (United States)

Thorpe, Dayton; Limmer, David; Chandler, David

2013-03-01

Charge transfer in solution, such as autoionization and ion pair dissociation in water, is governed by rare electric field fluctuations of the solvent. Knowing the statistics of such fluctuations can help explain the dynamics of these rare events. Trajectories short enough to be tractable by computer simulation are virtually certain not to sample the large fluctuations that promote rare events. Here, we employ importance sampling techniques with classical molecular dynamics simulations of liquid water to study statistics of electric field fluctuations far from their means. We find that the distributions of electric fields located on individual water molecules are not in general gaussian. Near the mean this non-gaussianity is due to the internal charge distribution of the water molecule. Further from the mean, however, there is a previously unreported Bjerrum-like defect that stabilizes certain large fluctuations out of equilibrium. As expected, differences in electric fields acting between molecules are gaussian to a remarkable degree. By studying these differences, though, we are able to determine what configurations result not only in large electric fields, but also in electric fields with long spatial correlations that may be needed to promote charge separation.

Electric field prediction for a human body-electric machine system.

Science.gov (United States)

Ioannides, Maria G; Papadopoulos, Peter J; Dimitropoulou, Eugenia

2004-01-01

A system consisting of an electric machine and a human body is studied and the resulting electric field is predicted. A 3-phase induction machine operating at full load is modeled considering its geometry, windings, and materials. A human model is also constructed approximating its geometry and the electric properties of tissues. Using the finite element technique the electric field distribution in the human body is determined for a distance of 1 and 5 m from the machine and its effects are studied. Particularly, electric field potential variations are determined at specific points inside the human body and for these points the electric field intensity is computed and compared to the limit values for exposure according to international standards.

Apparatuses and methods for generating electric fields

Science.gov (United States)

Scott, Jill R; McJunkin, Timothy R; Tremblay, Paul L

2013-08-06

Apparatuses and methods relating to generating an electric field are disclosed. An electric field generator may include a semiconductive material configured in a physical shape substantially different from a shape of an electric field to be generated thereby. The electric field is generated when a voltage drop exists across the semiconductive material. A method for generating an electric field may include applying a voltage to a shaped semiconductive material to generate a complex, substantially nonlinear electric field. The shape of the complex, substantially nonlinear electric field may be configured for directing charged particles to a desired location. Other apparatuses and methods are disclosed.

Electric Field Imaging

Data.gov (United States)

National Aeronautics and Space Administration — NDE historically has focused technology development in propagating wave phenomena with little attention to the field of electrostatics and emanating electric fields....

Electric field strength and focality in electroconvulsive therapy and magnetic seizure therapy: a finite element simulation study

Science.gov (United States)

Deng, Zhi-De; Lisanby, Sarah H.; Peterchev, Angel V.

2011-02-01

We present the first computational study comparing the electric field induced by various electroconvulsive therapy (ECT) and magnetic seizure therapy (MST) paradigms. Four ECT electrode configurations (bilateral, bifrontal, right unilateral, and focal electrically administered seizure therapy) and three MST coil configurations (circular, cap, and double cone) were modeled. The model incorporated a modality-specific neural activation threshold. ECT (0.3 ms pulse width) and MST induced the maximum electric field of 2.1-2.5 V cm-1 and 1.1-2.2 V cm-1 in the brain, corresponding to 6.2-7.2 times and 1.2-2.3 times the neural activation threshold, respectively. The MST electric field is more confined to the superficial cortex compared to ECT. The brain volume stimulated was much larger with ECT (up to 100%) than with MST (up to 8.2%). MST with the double-cone coil was the most focal, and bilateral ECT was the least focal. Our results suggest a possible biophysical explanation of the reduced side effects of MST compared to ECT. Our results also indicate that the conventional ECT pulse amplitude (800-900 mA) is much higher than necessary for seizure induction. Reducing the ECT pulse amplitude should be explored as a potential means of diminishing side effects.

Electrical field: a historical review of its application and contributions in wastewater sludge dewatering.

Science.gov (United States)

Mahmoud, Akrama; Olivier, Jérémy; Vaxelaire, Jean; Hoadley, Andrew F A

2010-04-01

Electric field-assisted dewatering, also called electro-dewatering, is a technology in which a conventional dewatering mechanism such a pressure dewatering is combined with electrokinetic effects to realize an improved liquid/solids separation, to increase the final dry solids content and to accelerate the dewatering process with low energy consumption compared to thermal drying. Electro-dewatering is not a new idea, but the practical industrial applications have been limited to niche areas in soil mechanics, civil engineering, and the ceramics industry. Recently, it has received great attention, specially, in the fields of fine-particle sludge, gelatinous sludge, sewage sludge, pharmaceutical industries, food waste and bull kelp, which could not be successfully dewatered with conventional mechanical methods. This review focuses on the scientific and practical aspects of the application of an electrical field in laboratory/industrial dewatering, and discusses this in relation to conventional dewatering techniques. A comprehensive bibliography of research in the electro-dewatering of wastewater sludges is included. As the fine-particle suspensions possess a surface charge, usually negative, they are surrounded by a layer with a higher density of positive charges, the electric double layer. When an electric field is applied, the usually negative charged particles move towards the electrode of the opposite charge. The water, commonly with cations, is driven towards the negative electrode. Electro-dewatering thus involves the well-known phenomena of electrophoresis, electro-osmosis, and electromigration. Following a detailed outline of the role of the electric double layer and electrokinetic phenomena, an analysis of the components of applied voltage and their significance is presented from an electrochemical viewpoint. The aim of this elementary analysis is to provide a fundamental understanding of the different process variables and configurations in order to

Dynamic behaviour of the silica-water-bio electrical double layer in the presence of a divalent electrolyte.

Science.gov (United States)

Lowe, B M; Maekawa, Y; Shibuta, Y; Sakata, T; Skylaris, C-K; Green, N G

2017-01-25

Electronic devices are becoming increasingly used in chemical- and bio-sensing applications and therefore understanding the silica-electrolyte interface at the atomic scale is becoming increasingly important. For example, field-effect biosensors (BioFETs) operate by measuring perturbations in the electric field produced by the electrical double layer due to biomolecules binding on the surface. In this paper, explicit-solvent atomistic calculations of this electric field are presented and the structure and dynamics of the interface are investigated in different ionic strengths using molecular dynamics simulations. Novel results from simulation of the addition of DNA molecules and divalent ions are also presented, the latter of particular importance in both physiological solutions and biosensing experiments. The simulations demonstrated evidence of charge inversion, which is known to occur experimentally for divalent electrolyte systems. A strong interaction between ions and DNA phosphate groups was demonstrated in mixed electrolyte solutions, which are relevant to experimental observations of device sensitivity in the literature. The bound DNA resulted in local changes to the electric field at the surface; however, the spatial- and temporal-mean electric field showed no significant change. This result is explained by strong screening resulting from a combination of strongly polarised water and a compact layer of counterions around the DNA and silica surface. This work suggests that the saturation of the Stern layer is an important factor in determining BioFET response to increased salt concentration and provides novel insight into the interplay between ions and the EDL.

ELECTRIC AND MAGNETIC FIELDS ELECTRIC AND GASOLINE-POWERED VEHICLES.

Science.gov (United States)

Tell, Richard A; Kavet, Robert

2016-12-01

Measurements were conducted to investigate electric and magnetic fields (EMFs) from 120 Hz to 10 kHz and 1.2 to 100 kHz in 9 electric or hybrid vehicles and 4 gasoline vehicles, all while being driven. The range of fields in the electric vehicles enclosed the range observed in the gasoline vehicles. Mean magnetic fields ranged from nominally 0.6 to 3.5 µT for electric/hybrids depending on the measurement band compared with nominally 0.4 to 0.6 µT for gasoline vehicles. Mean values of electric fields ranged from nominally 2 to 3 V m -1 for electric/hybrid vehicles depending on the band, compared with 0.9 to 3 V m -1 for gasoline vehicles. In all cases, the fields were well within published exposure limits for the general population. The measurements were performed with Narda model EHP-50C/EHP-50D EMF analysers that revealed the presence of spurious signals in the EHP-50C unit, which were resolved with the EHP-50D model. © The Author 2016. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

THREE-DIMENSIONAL NON-VACUUM PULSAR OUTER-GAP MODEL: LOCALIZED ACCELERATION ELECTRIC FIELD IN THE HIGHER ALTITUDES

Energy Technology Data Exchange (ETDEWEB)

Hirotani, Kouichi [Academia Sinica, Institute of Astronomy and Astrophysics (ASIAA), P.O. Box 23-141, Taipei, Taiwan (China)

2015-01-10

We investigate the particle accelerator that arises in a rotating neutron-star magnetosphere. Simultaneously solving the Poisson equation for the electro-static potential, the Boltzmann equations for relativistic electrons and positrons, and the radiative transfer equation, we demonstrate that the electric field is substantially screened along the magnetic field lines by pairs that are created and separated within the accelerator. As a result, the magnetic-field-aligned electric field is localized in higher altitudes near the light cylinder and efficiently accelerates the positrons created in the lower altitudes outward but does not accelerate the electrons inward. The resulting photon flux becomes predominantly outward, leading to typical double-peak light curves, which are commonly observed from many high-energy pulsars.

Numerical simulation of diffuse double layer around microporous electrodes based on the Poisson–Boltzmann equation

International Nuclear Information System (INIS)

Kitazumi, Yuki; Shirai, Osamu; Yamamoto, Masahiro; Kano, Kenji

2013-01-01

Graphical abstract: - Highlights: • Diffuse double layers overlap with each other in the micropore. • The overlapping of the diffuse double layer affects the double layer capacitance. • The electric field becomes weak in the micropore. • The electroneutrality is unsatisfactory in the micropore. - Abstract: The structure of the diffuse double layer around a nm-sized micropore on porous electrodes has been studied by numerical simulation using the Poisson–Boltzmann equation. The double layer capacitance of the microporous electrode strongly depends on the electrode potential, the electrolyte concentration, and the size of the micropore. The potential and the electrolyte concentration dependence of the capacitance is different from that of the planner electrode based on the Gouy's theory. The overlapping of the diffuse double layer becomes conspicuous in the micropore. The overlapped diffuse double layer provides the mild electric field. The intensified electric field exists at the rim of the orifice of the micropore because of the expansion of the diffuse double layers. The characteristic features of microporous electrodes are caused by the heterogeneity of the electric field around the micropores

The relationship between anatomically correct electric and magnetic field dosimetry and published electric and magnetic field exposure limits

International Nuclear Information System (INIS)

Kavet, R.; Dovan, T.; Patrick Reilly, J.

2012-01-01

Electric and magnetic field exposure limits published by International Commission for Non-Ionizing Radiation Protection and Inst. of Electrical and Electronics Engineers are aimed at protection against adverse electro-stimulation, which may occur by direct coupling to excitable tissue and, in the case of electric fields, through indirect means associated with surface charge effects (e.g. hair vibration, skin sensations), spark discharge and contact current. For direct coupling, the basic restriction (BR) specifies the not-to-be-exceeded induced electric field. The key results of anatomically based electric and magnetic field dosimetry studies and the relevant characteristics of excitable tissue were first identified. This permitted us to assess the electric and magnetic field exposure levels that induce dose in tissue equal to the basic restrictions, and the relationships of those exposure levels to the limits now in effect. We identify scenarios in which direct coupling of electric fields to peripheral nerve could be a determining factor for electric field limits. (authors)

Synaptic Effects of Electric Fields

Science.gov (United States)

Rahman, Asif

Learning and sensory processing in the brain relies on the effective transmission of information across synapses. The strength and efficacy of synaptic transmission is modifiable through training and can be modulated with noninvasive electrical brain stimulation. Transcranial electrical stimulation (TES), specifically, induces weak intensity and spatially diffuse electric fields in the brain. Despite being weak, electric fields modulate spiking probability and the efficacy of synaptic transmission. These effects critically depend on the direction of the electric field relative to the orientation of the neuron and on the level of endogenous synaptic activity. TES has been used to modulate a wide range of neuropsychiatric indications, for various rehabilitation applications, and cognitive performance in diverse tasks. How can a weak and diffuse electric field, which simultaneously polarizes neurons across the brain, have precise changes in brain function? Designing therapies to maximize desired outcomes and minimize undesired effects presents a challenging problem. A series of experiments and computational models are used to define the anatomical and functional factors leading to specificity of TES. Anatomical specificity derives from guiding current to targeted brain structures and taking advantage of the direction-sensitivity of neurons with respect to the electric field. Functional specificity originates from preferential modulation of neuronal networks that are already active. Diffuse electric fields may recruit connected brain networks involved in a training task and promote plasticity along active synaptic pathways. In vitro, electric fields boost endogenous synaptic plasticity and raise the ceiling for synaptic learning with repeated stimulation sessions. Synapses undergoing strong plasticity are preferentially modulated over weak synapses. Therefore, active circuits that are involved in a task could be more susceptible to stimulation than inactive circuits

Pressure, temperature, and electric field dependence of phase transformations in niobium modified 95/5 lead zirconate titanate

Energy Technology Data Exchange (ETDEWEB)

Dong, Wen D.; Carlos Valadez, J.; Gallagher, John A.; Jo, Hwan R.; Lynch, Christopher S., E-mail: cslynch@seas.ucla.edu [Department of Mechanical and Aerospace Engineering, The University of California, Los Angeles, 420 Westwood Plaza, Los Angeles, California 90095 (United States); Sahul, Raffi; Hackenberger, Wes [TRS Technologies, 2820 East College Avenue, State College, Pennsylvania 16801 (United States)

2015-06-28

Ceramic niobium modified 95/5 lead zirconate-lead titanate (PZT) undergoes a pressure induced ferroelectric to antiferroelectric phase transformation accompanied by an elimination of polarization and a volume reduction. Electric field and temperature drive the reverse transformation from the antiferroelectric to ferroelectric phase. The phase transformation was monitored under pressure, temperature, and electric field loading. Pressures and temperatures were varied in discrete steps from 0 MPa to 500 MPa and 25 °C to 125 °C, respectively. Cyclic bipolar electric fields were applied with peak amplitudes of up to 6 MV m{sup −1} at each pressure and temperature combination. The resulting electric displacement–electric field hysteresis loops were open “D” shaped at low pressure, characteristic of soft ferroelectric PZT. Just below the phase transformation pressure, the hysteresis loops took on an “S” shape, which split into a double hysteresis loop just above the phase transformation pressure. Far above the phase transformation pressure, when the applied electric field is insufficient to drive an antiferroelectric to ferroelectric phase transformation, the hysteresis loops collapse to linear dielectric behavior. Phase stability maps were generated from the experimental data at each of the temperature steps and used to form a three dimensional pressure–temperature–electric field phase diagram.

Magnetic resonance electrical impedance tomography for determining electric field distribution during electroporation

International Nuclear Information System (INIS)

Kranjc, Matej; Miklavcic, Damijan; Bajd, Franci; Serša, Igor

2013-01-01

Electroporation is a phenomenon caused by externally applied electric field to cells that results in an increase of cell membrane permeability to various molecules. Accurate coverage of the tissue with a sufficiently large electric field presents one of the most important conditions for successful membrane permeabilization. Applications based on electroporation would greatly benefit with a method for monitoring the electric field, especially if it could be done in situ. As the membrane electroporation is a consequence of an induced transmembrane potential, which is directly proportional to the local electric field, we have been investigating current density imaging and magnetic resonance electrical impedance tomography techniques to determine the electric field distribution during electroporation. In this paper, we present comparison of current density and electric field distribution in an agar phantom and in a liver tissue exposed to electroporation pulses. As expected, a region of increased electrical conductivity was observed in the liver tissue exposed to sufficiently high electric field but not in agar phantom.

Underwater electric field detection system based on weakly electric fish

Science.gov (United States)

Xue, Wei; Wang, Tianyu; Wang, Qi

2018-04-01

Weakly electric fish sense their surroundings in complete darkness by their active electric field detection system. However, due to the insufficient detection capacity of the electric field, the detection distance is not enough, and the detection accuracy is not high. In this paper, a method of underwater detection based on rotating current field theory is proposed to improve the performance of underwater electric field detection system. First of all, we built underwater detection system based on the theory of the spin current field mathematical model with the help of the results of previous researchers. Then we completed the principle prototype and finished the metal objects in the water environment detection experiments, laid the foundation for the further experiments.

A comparison of ionizing radiation and high field stress effects in n-channel power vertical double-diffused metal-oxide-semiconductor field-effect transistors

International Nuclear Information System (INIS)

Park, Mun-Soo; Na, Inmook; Wie, Chu R.

2005-01-01

n-channel power vertical double-diffused metal-oxide-semiconductor field-effect-transistor (VDMOSFET) devices were subjected to a high electric field stress or to a x-ray radiation. The current-voltage and capacitance-voltage measurements show that the channel-side interface and the drain-side interface are affected differently in the case of high electric field stress, whereas the interfaces are nearly uniformly affected in the case of x-ray radiation. This paper also shows that for the gated diode structure of VDMOSFET, the direct-current current-voltage technique measures only the drain-side interface; the subthreshold current-voltage technique measures only the channel-side interface; and the capacitance-voltage technique measures both interfaces simultaneously and clearly distinguishes the two interfaces. The capacitance-voltage technique is suggested to be a good quantitative method to examine both interface regions by a single measurement

Strategy for improved frequency response of electric double-layer capacitors

Science.gov (United States)

Wada, Yoshifumi; Pu, Jiang; Takenobu, Taishi

2015-10-01

We propose a strategy for improving the response speed of electric double-layer capacitors (EDLCs) and electric double-layer transistors (EDLTs), based on an asymmetric structure with differently sized active materials and gate electrodes. We validate the strategy analytically by a classical calculation and experimentally by fabricating EDLCs with asymmetric Au electrodes (1:50 area ratio and 7.5 μm gap distance). The performance of the EDLCs is compared with that of conventional symmetric EDLCs. Our strategy dramatically improved the cut-off frequency from 14 to 93 kHz and this improvement is explained by fast charging of smaller electrodes. Therefore, this approach is particularly suitable to EDLTs, potentially expanding the applicability to medium speed (kHz-MHz) devices.

African electricity market liberalization, competition and structuring: Should double bid markets be set up?

International Nuclear Information System (INIS)

Founanou, M.

2011-01-01

In this paper, we analyse the possibility of using double auction mechanisms in the organization of the electricity markets in African countries. Today's electricity markets around the world are de-regulated and going through a restructuring process. In a context marked by the opening up to competition, a double auction for electricity supply is henceforth used to set prices in wholesale and retail electricity markets. Game theory analysis useful for studying the double auction prices proprieties. The double auction is a non-cooperative game, which is strategically equivalent to the auctions theory. The price formed, depending on the buyers and sellers' strategies, is a competitive price, which tends to the ideal price when competition operates intensely on both sides of market. For Africa, the presence of congestion costs and a chronic lack of capacity require the search for other solutions. We investigate optimal strategic behaviour when buyers and sellers are separated by a possibly constrained transmission line and show that bidders' strategies converge to truth-telling behaviour as the number of market participants increases. In the congestion case, this fails to occur. We also investigate how participants in wholesale electricity markets modify their bidding strategies as a function of the influence and behaviour of a transmission line owner. (author)

Double-sided auction mechanism design in electricity based on maximizing social welfare

International Nuclear Information System (INIS)

Zou Xiaoyan

2009-01-01

An efficient electricity double-sided auction mechanism should control market power and enhance the social welfare of the electricity market. Based on this goal, the paper designs a new double-sided auction mechanism. In the new mechanism, the social welfare contribution of each participant plays a pivotal role, because this contribution is the critical factor in market clearing, payment settling, and transaction matching rules. In particular, each winner of the auction can gain transfer payments according to his contribution to social welfare in the electricity market, and this gives the mechanism the ability to control the market power of some participants. At the same time, this mechanism ensures that the market organizer balances his budget. We then conduct a theoretical and empirical analysis based on the Spanish electricity market. Both of the results show that compared to the uniform-pricing mechanism, the new mechanism can reduce market power of participants and enhance the social welfare of the electricity market.

Tripolar electric field Structure in guide field magnetic reconnection

OpenAIRE

S. Fu; S. Huang; M. Zhou; B. Ni; X. Deng

2018-01-01

It has been shown that the guide field substantially modifies the structure of the reconnection layer. For instance, the Hall magnetic and electric fields are distorted in guide field reconnection compared to reconnection without guide fields (i.e., anti-parallel reconnection). In this paper, we performed 2.5-D electromagnetic full particle simulation to study the electric field structures in magnetic reconnection under different initial guide fields (Bg). Once the amplit...

Study of the electric Held in HTS tape caused by perpendicular AC magnetic field

International Nuclear Information System (INIS)

Roiberg, V; Kopansky, F.

2004-01-01

Full Text: In a previous work we studied the influence of AC magnetic fields on voltage-currents (V-I) characteristics of high temperature superconducting (HTS) multi filament BSCC0-2223 tapes. It was found that AC magnetic fields perpendicular to the ab plane (the wide surface of the tape) cause a linear decrease of the critical current (IC) with amplitude of the AC magnetic field. The degradation of IC in .AC field was explained by the geometrical model according to which the transport current floe: is confined to the central zone of the tape where .AC field does not penetrate. For deeper understanding of the observed phenomena we carried out a study of the time dependence of the electric field during the cycle of AC field. At the same time we expanded the frequency range to low frequencies down to 1 Hz. The main results of the work are as following. 1. The time modulation of the electric field E in the HTS tape carrying transport DC current has the double frequency relating to AC magnetic field. 2. In field amplitudes less than 70 G the electric field modulation decreases with increasing frequency in opposite to its well-pronounced increase in higher AC field amplitudes. Alcove 70 G, the electric field increases with increasing the frequency of the external magnetic field. The wave forms of the electric field are different in both amplitudes ranges. 3. E-I curves of the tape in low amplitudes are frequency independent and coincide with E-l curves in AC field with intensity equal to the AC field amplitude. 4. In high AC field amplitudes, a strong dependence of the E-I curves on frequency is observed in the frequency range of 1-40 Hz and no dependence is observed in higher frequencies. Our results suggest that a combination of the geometrical model with flux creep concepts is necessary for a better understanding of the electric field behavior in our measurement conditions

Electric field-induced valley degeneracy lifting in uniaxial strained graphene: evidence from magnetophonon resonance

OpenAIRE

Assili, Mohamed; Haddad, Sonia; Kang, Woun

2015-01-01

A double peak structure in the magneto-phonon resonance (MPR) spectrum of uniaxial strained graphene, under crossed electric and magnetic fields, is predicted. We focus on the $\\Gamma$ point optical phonon modes coupled to the inter-Landau level transitions $0 \\leftrightarrows \\pm 1$ where MPR is expected to be more pronounced at high magnetic field. We derive the frequency shifts and the broadenings of the longitudinal (LO) and transverse (TO) optical phonon modes taking into account the eff...

Improving Breakdown Behavior by Substrate Bias in a Novel Double Epi-layer Lateral Double Diffused MOS Transistor

International Nuclear Information System (INIS)

Li Qi; Wang Wei-Dong; Liu Yun; Wei Xue-Ming

2012-01-01

A new lateral double diffused MOS (LDMOS) transistor with a double epitaxial layer formed by an n-type substrate and a p-type epitaxial layer is reported (DEL LDMOS). The mechanism of the improved breakdown characteristic is that the high electric field around the drain is reduced by substrate reverse bias, which causes the redistribution of the bulk electric field in the drift region, and the vertical blocking voltage is shared by the drain side and the source side. The numerical results indicate that the trade-off between breakdown voltage and on-resistance of the proposed device is improved greatly in comparison to that of the conventional LDMOS. (condensed matter: electronic structure, electrical, magnetic, and optical properties)

Dual double field theory

Energy Technology Data Exchange (ETDEWEB)

Bergshoeff, Eric A. [Centre for Theoretical Physics, University of Groningen,Nijenborgh 4, 9747 AG Groningen (Netherlands); Hohm, Olaf [Simons Center for Geometry and Physics, Stony Brook University,Stony Brook, NY 11794-3636 (United States); Penas, Victor A. [Centre for Theoretical Physics, University of Groningen,Nijenborgh 4, 9747 AG Groningen (Netherlands); Riccioni, Fabio [INFN - Sezione di Roma, Dipartimento di Fisica, Università di Roma “La Sapienza”,Piazzale Aldo Moro 2, 00185 Roma (Italy)

2016-06-06

We present the dual formulation of double field theory at the linearized level. This is a classically equivalent theory describing the duals of the dilaton, the Kalb-Ramond field and the graviton in a T-duality or O(D,D) covariant way. In agreement with previous proposals, the resulting theory encodes fields in mixed Young-tableau representations, combining them into an antisymmetric 4-tensor under O(D,D). In contrast to previous proposals, the theory also requires an antisymmetric 2-tensor and a singlet, which are not all pure gauge. The need for these additional fields is analogous to a similar phenomenon for “exotic' dualizations, and we clarify this by comparing with the dualizations of the component fields. We close with some speculative remarks on the significance of these observations for the full non-linear theory yet to be constructed.

Detection of electric field around field-reversed configuration plasma

International Nuclear Information System (INIS)

Ikeyama, Taeko; Hiroi, Masanori; Nogi, Yasuyuki; Ohkuma, Yasunori

2010-01-01

Electric-field probes consisting of copper plates are developed to measure electric fields in a vacuum region around a plasma. The probes detect oscillating electric fields with a maximum strength of approximately 100 V/m through a discharge. Reproducible signals from the probes are obtained with an unstable phase dominated by a rotational instability. It is found that the azimuthal structure of the electric field can be explained by the sum of an n=2 mode charge distribution and a convex-surface electron distribution on the deformed separatrix at the unstable phase. The former distribution agrees with that anticipated from the diamagnetic drift motions of plasma when the rotational instability occurs. The latter distribution suggests that an electron-rich plasma covers the separatrix.

Mean-Field Theory of Electrical Double Layer In Ionic Liquids with Account of Short-Range Correlations

International Nuclear Information System (INIS)

Goodwin, Zachary A.H.; Feng, Guang; Kornyshev, Alexei A.

2017-01-01

We develop the theory of the electrical double layer in ionic liquids as proposed earlier by Kornyshev (2007). In the free energy function we keep the so called ‘short-range correlation terms’ which were omitted there. With some simplifying assumptions, we arrive at a modified expression for differential capacitance, which makes differential capacitance curves less sharply depending on electrode potential and having smaller values at extrema than in the previous theory. This brings the results closer to typical experimental observations, and makes it appealing to use this formalism for treatment of experimental data. Implications on Debye length and the extent of ion paring in ionic liquids are then briefly discussed.

Quantifying the thickness of the electrical double layer neutralizing a planar electrode: the capacitive compactness.

Science.gov (United States)

Guerrero-García, Guillermo Iván; González-Tovar, Enrique; Chávez-Páez, Martín; Kłos, Jacek; Lamperski, Stanisław

2017-12-20

The spatial extension of the ionic cloud neutralizing a charged colloid or an electrode is usually characterized by the Debye length associated with the supporting charged fluid in the bulk. This spatial length arises naturally in the linear Poisson-Boltzmann theory of point charges, which is the cornerstone of the widely used Derjaguin-Landau-Verwey-Overbeek formalism describing the colloidal stability of electrified macroparticles. By definition, the Debye length is independent of important physical features of charged solutions such as the colloidal charge, electrostatic ion correlations, ionic excluded volume effects, or specific short-range interactions, just to mention a few. In order to include consistently these features to describe more accurately the thickness of the electrical double layer of an inhomogeneous charged fluid in planar geometry, we propose here the use of the capacitive compactness concept as a generalization of the compactness of the spherical electrical double layer around a small macroion (González-Tovar et al., J. Chem. Phys. 2004, 120, 9782). To exemplify the usefulness of the capacitive compactness to characterize strongly coupled charged fluids in external electric fields, we use integral equations theory and Monte Carlo simulations to analyze the electrical properties of a model molten salt near a planar electrode. In particular, we study the electrode's charge neutralization, and the maximum inversion of the net charge per unit area of the electrode-molten salt system as a function of the ionic concentration, and the electrode's charge. The behaviour of the associated capacitive compactness is interpreted in terms of the charge neutralization capacity of the highly correlated charged fluid, which evidences a shrinking/expansion of the electrical double layer at a microscopic level. The capacitive compactness and its first two derivatives are expressed in terms of experimentally measurable macroscopic properties such as the

Current limitation by an electric double layer in ion laser discharges

International Nuclear Information System (INIS)

Torven, S.

1977-12-01

A theory for current limitation in ion laser discharges is investigated. The basic mechanism considered is saturation of the positive ion flux at an electric double layer by the limited flux of neutral atoms. The result is compared with a recently published synthesis of a large number of experimental data which agree well with those predicted by the double layer model

Double unification of particles with fields and electricity with gravity in non-empty space of continuous complex energies

Directory of Open Access Journals (Sweden)

Bulyzhenkov Igor E.

2016-01-01

Full Text Available Non-empty space reading of Maxwell equations as local energy identities explains why a Coulomb field is carried rigidly by electrons in experiments. The analytical solution of the Poisson equation defines the sharp radial shape of charged elementary densities which are proportional to continuous densities of electric self-energy. Both Coulomb field and radial charge densities are free from energy divergences. Non-empty space of electrically charged mass-energy can be described by complex analytical densities resulting in real values for volume mass integrals and in imaginary values for volume charge integrals. Imaginary electric charges in the Newton gravitational law comply with real Coulomb forces. Unification of forces through complex charges rids them of radiation self-acceleration. Strong gravitational fields repeal probe bodies that might explainthe accelerated expansion of the dense Metagalaxy. Outward and inward spherical waves form the standing wave process within the radial carrier of complex energy.

Nanomechanical electric and electromagnetic field sensor

Science.gov (United States)

Datskos, Panagiotis George; Lavrik, Nickolay

2015-03-24

The present invention provides a system for detecting and analyzing at least one of an electric field and an electromagnetic field. The system includes a micro/nanomechanical oscillator which oscillates in the presence of at least one of the electric field and the electromagnetic field. The micro/nanomechanical oscillator includes a dense array of cantilevers mounted to a substrate. A charge localized on a tip of each cantilever interacts with and oscillates in the presence of the electric and/or electromagnetic field. The system further includes a subsystem for recording the movement of the cantilever to extract information from the electric and/or electromagnetic field. The system further includes a means of adjusting a stiffness of the cantilever to heterodyne tune an operating frequency of the system over a frequency range.

Monitoring of interaction of low-frequency electric field with biological tissues upon optical clearing with optical coherence tomography.

Science.gov (United States)

Peña, Adrián F; Doronin, Alexander; Tuchin, Valery V; Meglinski, Igor

2014-08-01

The influence of a low-frequency electric field applied to soft biological tissues ex vivo at normal conditions and upon the topical application of optical clearing agents has been studied by optical coherence tomography (OCT). The electro-kinetic response of tissues has been observed and quantitatively evaluated by the double correlation OCT approach, utilizing consistent application of an adaptive Wiener filtering and Fourier domain correlation algorithm. The results show that fluctuations, induced by the electric field within the biological tissues are exponentially increased in time. We demonstrate that in comparison to impedance measurements and the mapping of the temperature profile at the surface of the tissue samples, the double correlation OCT approach is much more sensitive to the changes associated with the tissues' electro-kinetic response. We also found that topical application of the optical clearing agent reduces the tissues' electro-kinetic response and is cooling the tissue, thus reducing the temperature induced by the electric current by a few degrees. We anticipate that dcOCT approach can find a new application in bioelectrical impedance analysis and monitoring of the electric properties of biological tissues, including the resistivity of high water content tissues and its variations.

Molecular dynamics in high electric fields

International Nuclear Information System (INIS)

Apostol, M.; Cune, L.C.

2016-01-01

Highlights: • New method for rotation molecular spectra in high electric fields. • Parametric resonances – new features in spectra. • New elementary excitations in polar solids from dipolar interaction (“dipolons”). • Discussion about a possible origin of the ferroelectricity from dipolar interactions. - Abstract: Molecular rotation spectra, generated by the coupling of the molecular electric-dipole moments to an external time-dependent electric field, are discussed in a few particular conditions which can be of some experimental interest. First, the spherical-pendulum molecular model is reviewed, with the aim of introducing an approximate method which consists in the separation of the azimuthal and zenithal motions. Second, rotation spectra are considered in the presence of a static electric field. Two particular cases are analyzed, corresponding to strong and weak fields. In both cases the classical motion of the dipoles consists of rotations and vibrations about equilibrium positions; this motion may exhibit parametric resonances. For strong fields a large macroscopic electric polarization may appear. This situation may be relevant for polar matter (like pyroelectrics, ferroelectrics), or for heavy impurities embedded in a polar solid. The dipolar interaction is analyzed in polar condensed matter, where it is shown that new polarization modes appear for a spontaneous macroscopic electric polarization (these modes are tentatively called “dipolons”); one of the polarization modes is related to parametric resonances. The extension of these considerations to magnetic dipoles is briefly discussed. The treatment is extended to strong electric fields which oscillate with a high frequency, as those provided by high-power lasers. It is shown that the effect of such fields on molecular dynamics is governed by a much weaker, effective, renormalized, static electric field.

Atomistic modeling of metal surfaces under electric fields: direct coupling of electric fields to a molecular dynamics algorithm

CERN Document Server

Djurabekova, Flyura; Pohjonen, Aarne; Nordlund, Kai

2011-01-01

The effect of electric fields on metal surfaces is fairly well studied, resulting in numerous analytical models developed to understand the mechanisms of ionization of surface atoms observed at very high electric fields, as well as the general behavior of a metal surface in this condition. However, the derivation of analytical models does not include explicitly the structural properties of metals, missing the link between the instantaneous effects owing to the applied field and the consequent response observed in the metal surface as a result of an extended application of an electric field. In the present work, we have developed a concurrent electrodynamic–molecular dynamic model for the dynamical simulation of an electric-field effect and subsequent modification of a metal surface in the framework of an atomistic molecular dynamics (MD) approach. The partial charge induced on the surface atoms by the electric field is assessed by applying the classical Gauss law. The electric forces acting on the partially...

Impacts of ionospheric electric fields on the GPS tropospheric delays during geomagnetic storms in Antarctica

International Nuclear Information System (INIS)

Suparta, W

2017-01-01

This paper aimed to overview the interaction of the thunderstorm with the ionospheric electric fields during major geomagnetic storms in Antarctica through the GPS tropospheric delays. For the purpose of study, geomagnetic activity and electric fields data for the period from 13 to 21 March 2015 representing the St. Patrick’s Day storm is analyzed. To strengthen the analysis, data for the period of 27 October to 1 st November 2003 representing for the Halloween storm is also compared. Our analysis showed that both geomagnetic storms were severe ( Ap ≥ 100 nT), where the intensity of Halloween storm is double compared to St. Patrick’s Day storm. For the ionospheric electric field, the peaks were dropped to -1.63 mV/m and -2.564 mV/m for St. Patrick and Halloween storms, respectively. At this time, the interplanetary magnetic field Bz component was significantly dropped to -17.31 nT with Ap > 150 nT (17 March 2015 at 19:20 UT) and -26.51 nT with Ap = 300 nT (29 October 2003 at 19:40 UT). For both geomagnetic storms, the electric field was correlated well with the ionospheric activity where tropospheric delays show a different characteristic. (paper)

Observations of propagating double layers in a high current discharge

International Nuclear Information System (INIS)

Lindberg, L.

1988-01-01

Observations of current disruptions and strong electric fields along the magnetic field in a high-density (2 x 10 19 m - 3 , highly-ionized, moving, and expanding plasma column are reported. The electric field is interpreted in terms of propagating, strong electric double layers (3-5kV). An initial plasma column is formed in an axial magnetic field (0.1T) by means of a conical theta-pinch plasma gun. When an axial current (max 5kA, 3-5 kV) is drawn through the column spontaneous disruptions and double-layer formation occur within a few microseconds. Floating, secondary emitting Langmuir probes are used. They often indicate very high positive potential peaks (1-2 kV above the anode potential during a few μs) in the plasma on the positive side of the double layer. Short, intense bursts of HF radiation are detected at the disruptions

The electric double layer has a life of its own

NARCIS (Netherlands)

Merlet, Céline; Limmer, David T.; Salanne, Mathieu; Van Roij, René; Madden, Paul A.; Chandler, David; Rotenberg, Benjamin

2014-01-01

Using molecular dynamics simulations with recently developed importance sampling methods, we show that the differential capacitance of a model ionic liquid based double-layer capacitor exhibits an anomalous dependence on the applied electrical potential. Such behavior is qualitatively incompatible

ESTIMATING ELECTRIC FIELDS FROM VECTOR MAGNETOGRAM SEQUENCES

International Nuclear Information System (INIS)

Fisher, G. H.; Welsch, B. T.; Abbett, W. P.; Bercik, D. J.

2010-01-01

Determining the electric field distribution on the Sun's photosphere is essential for quantitative studies of how energy flows from the Sun's photosphere, through the corona, and into the heliosphere. This electric field also provides valuable input for data-driven models of the solar atmosphere and the Sun-Earth system. We show how observed vector magnetogram time series can be used to estimate the photospheric electric field. Our method uses a 'poloidal-toroidal decomposition' (PTD) of the time derivative of the vector magnetic field. These solutions provide an electric field whose curl obeys all three components of Faraday's Law. The PTD solutions are not unique; the gradient of a scalar potential can be added to the PTD electric field without affecting consistency with Faraday's Law. We then present an iterative technique to determine a potential function consistent with ideal MHD evolution; but this field is also not a unique solution to Faraday's Law. Finally, we explore a variational approach that minimizes an energy functional to determine a unique electric field, a generalization of Longcope's 'Minimum Energy Fit'. The PTD technique, the iterative technique, and the variational technique are used to estimate electric fields from a pair of synthetic vector magnetograms taken from an MHD simulation; and these fields are compared with the simulation's known electric fields. The PTD and iteration techniques compare favorably to results from existing velocity inversion techniques. These three techniques are then applied to a pair of vector magnetograms of solar active region NOAA AR8210, to demonstrate the methods with real data. Careful examination of the results from all three methods indicates that evolution of the magnetic vector by itself does not provide enough information to determine the true electric field in the photosphere. Either more information from other measurements, or physical constraints other than those considered here are necessary to find

Numerical analysis of magnetic field effects on hydro-thermal behavior of a magnetic nanofluid in a double pipe heat exchanger

Energy Technology Data Exchange (ETDEWEB)

Shakiba, Ali, E-mail: Shakiba7858@yahoo.com [Department of Mechanical Engineering, Mazandaran Institute of Technology, Babol (Iran, Islamic Republic of); Vahedi, Khodadad, E-mail: Khvahedi@ihu.ac.ir [Department of Mechanical Engineering, Imam Hossein University, Tehran (Iran, Islamic Republic of)

2016-03-15

This study attempts to numerically investigate the hydro-thermal characteristics of a ferrofluid (water and 4 vol% Fe{sub 3}O{sub 4}) in a counter-current horizontal double pipe heat exchanger, which is exposed to a non-uniform transverse magnetic field with different intensities. The magnetic field is generated by an electric current going through a wire located parallel to the inner tube and between two pipes. The single phase model and the control volume technique have been used to study the flow. The effects of magnetic field have been added to momentum equation by applying C++ codes in Ansys Fluent 14. The results show that applying this kind of magnetic field causes kelvin force to be produced perpendicular to the ferrofluid flow, changing axial velocity profile and creating a pair of vortices which leads to an increase in Nusselt number, friction factor and pressure drop. Comparing the enhancement percentage of Nusselt number, friction factor and pressure drop demonstrates that the optimum value of magnetic number for Re{sub ff}=50 is between Mn=1.33×10{sup 6} and Mn=2.37×10{sup 6}. So applying non-uniform transverse magnetic field can control the flow of ferrofluid and improve heat transfer process of double pipe heat exchanger. - Highlights: • Effect of applying non-uniform transverse magnetic field on a ferrofluid for enhancing the cooling process in a double pipe heat exchanger is investigated. • Heat exchanger is exposed to a non-uniform transverse magnetic field with different intensities. • The magnetic field is generated by an electric current going through a wire located parallel to inner tube and between two pipes. • Applying this field produces kelvin force to change axial velocity profile and creating a pair of vortices increasing Nusselt number, friction factor and pressure drop.

Effect of applied DC electric fields in flame spread over polyethylene-coated electrical wire

KAUST Repository

Jin, Young Kyu

2011-03-01

We experimentally investigated the effect of applied DC electric fields on the flame spread over polyethylene-coated electrical wire. The flame-spread rates over electrical wire with negative and positive DC electric fields from 0 to ±7 kV were measured and analyzed. We compared the results for DC electric fields with previous results for AC electric fields. We explored whether or not various flame shapes could be obtained with DC electric fields and the main reason for the flame-spread acceleration, particularly at the end of the electrical wire, for AC electric fields. We found that DC electric fields do not significantly affect the flame-spread rates. However, the flame shape is mildly altered by the ionic wind effect even for DC electric fields. The flame-spread rate is relevant to the flame shape and the slanted direction in spite of the mild impact. A possible explanation for the flame spread is given by a thermal-balance mechanism and fuel-vapor jet. © 2011 The Korean Society of Mechanical Engineers.

Electric field gradients in metals

International Nuclear Information System (INIS)

Schatz, G.

1979-01-01

A review of the recent works on electric field gradient in metals is given. The main emphasis is put on the temperature dependence of the electric field gradient in nonmagnetic metals. Some methods of investigation of this effect using nuclear probes are described. One of them is nuclear accoustic resonance method. (S.B.)

Static electric fields modify the locomotory behaviour of cockroaches.

Science.gov (United States)

Jackson, Christopher W; Hunt, Edmund; Sharkh, Suleiman; Newland, Philip L

2011-06-15

Static electric fields are found throughout the environment and there is growing interest in how electric fields influence insect behaviour. Here we have analysed the locomotory behaviour of cockroaches (Periplaneta americana) in response to static electric fields at levels equal to and above those found in the natural environment. Walking behaviour (including velocity, distance moved, turn angle and time spent walking) were analysed as cockroaches approached an electric field boundary in an open arena, and also when continuously exposed to an electric field. On approaching an electric field boundary, the greater the electric field strength the more likely a cockroach would be to turn away from, or be repulsed by, the electric field. Cockroaches completely exposed to electric fields showed significant changes in locomotion by covering less distance, walking slowly and turning more often. This study highlights the importance of electric fields on the normal locomotory behaviour of insects.

Electric field studies: TLE-induced waveforms and ground conductivity impact on electric field propagation

Science.gov (United States)

Farges, Thomas; Garcia, Geraldine; Blanc, Elisabeth

2010-05-01

We review in this paper main results obtained from electric field (from VLF to HF) measurement campaigns realized by CEA in the framework of the Eurosprite program [Neubert et al., 2005, 2008] from 2003 to 2009 in France in different configurations. Two main topics have been studied: sprite or elve induced phenomena (radiation or perturbation) and wave propagation. Using a network of 4 stations, VLF radiations from sprite have been successfully located at 10 km from the sprite parent lightning, in agreement with possible sprite location, generally displaced from the parent lightning. The MF (300 kHz - 3 MHz) source bursts were identified simultaneously with the occurrence of sprites observed with cameras [Farges et al., 2004; Neubert et al., 2008]. These observations are compared to recent broadband measurements, assumed to be due to relativistic electron beam radiation related to sprites [Fullekrug et al., 2009]. Recently, in 2009, with a new instrumentation, an ELF tail has been clearly measured after the lightning waveform, while sprites were observed at about 500 km from our station. This ELF tail is usually observed at distances higher than thousand km and is associated to sprite generation. This opens the capacity to measure the charge moment of the parent-lightning, using such measurement close to the source. Farges et al. [2007] showed that just after a lightning return stroke, a strong transient attenuation is very frequently observed in the MF waves of radio transmissions. They showed that this perturbation is due to heating of the lower ionosphere by the lightning-induced EMP during few milliseconds. These perturbations are then the MF radio signature of the lightning EMP effects on the lower ionosphere, in the same way as elves correspond to their optical signature. The experiment also provided the electric field waveforms directly associated to elves, while lightning were not detected by Météorage. Many of them present a double peak feature. The

Electric field mapping and auroral Birkeland currents

International Nuclear Information System (INIS)

Kaufmann, R.L.; Larson, D.J.

1989-01-01

Magnetic field lines, electric fields and equipotentials have been mapped throughout the magnetosphere in the vicinity of strong Birkeland currents. It was found that a uniform electric field at either the ionospheric or the equatorial end of a field line can map to a highly structured field at the other end if strong Birkeland currents are located nearby. The initiation of sheet currents of the region 1 - region 2 scale size and intensity resulted in magnetic field line displacements of about 1/2 hour in local time between equatorial and ionospheric end points. As a result, a uniform dawn to dusk electric field at the equator mapped to an ionospheric electric field with strong inward pointing components in the dusk hemisphere. Similar distortions were produced by Birkeland currents associated with narrow east-west-aligned auroral arcs. A specific model for the auroral current system, based on ionospheric measurements during a large substorm, was used to study effects seen during disturbed periods. An iterative procedure was developed to generate a self-consistent current system even in the presence of highly twisted field lines. The measured ionospheric electric field was projected tot he equatorial plane in the presence of the model Birkeland current system. Several physical processes were seen to influence ionospheric and equatorial electric fields, and the associated plasma convection, during a substorm

Electric field with bipolar structure during magnetic reconnection without a guide field

Science.gov (United States)

Guo, Jun

2014-05-01

We present a study on the polarized electric field during the collisionless magnetic reconnection of antiparallel fields using two dimensional particle-in-cell simulations. The simulations demonstrate clearly that electron holes and electric field with bipolar structure are produced during magnetic reconnection without a guide field. The electric field with bipolar structure can be found near the X-line and on the separatrix and the plasma sheet boundary layer, which is consistent with the observations. These structures will elongate electron's time staying in the diffusion region. In addition, the electric fields with tripolar structures are also found in our simulation.

Role of Electrical Double Layer Structure in Ionic Liquid Gated Devices.

Science.gov (United States)

Black, Jennifer M; Come, Jeremy; Bi, Sheng; Zhu, Mengyang; Zhao, Wei; Wong, Anthony T; Noh, Joo Hyon; Pudasaini, Pushpa R; Zhang, Pengfei; Okatan, Mahmut Baris; Dai, Sheng; Kalinin, Sergei V; Rack, Philip D; Ward, Thomas Zac; Feng, Guang; Balke, Nina

2017-11-22

Ionic liquid gating of transition metal oxides has enabled new states (magnetic, electronic, metal-insulator), providing fundamental insights into the physics of strongly correlated oxides. However, despite much research activity, little is known about the correlation of the structure of the liquids in contact with the transition metal oxide surface, its evolution with the applied electric potential, and its correlation with the measured electronic properties of the oxide. Here, we investigate the structure of an ionic liquid at a semiconducting oxide interface during the operation of a thin film transistor where the electrical double layer gates the device using experiment and theory. We show that the transition between the ON and OFF states of the amorphous indium gallium zinc oxide transistor is accompanied by a densification and preferential spatial orientation of counterions at the oxide channel surface. This process occurs in three distinct steps, corresponding to ion orientations, and consequently, regimes of different electrical conductivity. The reason for this can be found in the surface charge densities on the oxide surface when different ion arrangements are present. Overall, the field-effect gating process is elucidated in terms of the interfacial ionic liquid structure, and this provides unprecedented insight into the working of a liquid gated transistor linking the nanoscopic structure to the functional properties. This knowledge will enable both new ionic liquid design as well as advanced device concepts.

Electric-double-layer potential distribution in multiple-layer immiscible electrolytes

NARCIS (Netherlands)

Das, S.; Hardt, Steffen

2011-01-01

In this Brief Report, we calculate the electric-double-layer (EDL) electrostatic potential in a system of several layers of immiscible electrolytes. Verwey-Niessen theory predicts that at the interface between two immiscible electrolytes back-to-back EDLs are formed. The present analysis extends

Electric conductivity of TlInTe2 monocrystal in strong electric fields

International Nuclear Information System (INIS)

Zarbaliev, M.M.; Godzhaev, Eh.M.; Gadzhiev, V.A.

1980-01-01

Electric condUctivity of the TlInTe 2 single crystal in strong electric fields has been studied in the range of 77-300 K. The electron part of the TlInTe 2 dielectric constant has been found to be 4. The dependence of the activation energy of current carriers on the electric field strength is constructed and the value of the activation energy of current carriers in the absence of an electric field is determined by the extrapolation method. The results of the experiments are in good agreement with the Frenkel-Pool theory, and this affords grounds for asserting that the obtained dependences of electric conductivity on temperature and the electric field strength are defined by variation in the current carrier concentration due to action of the thermal-electron ionization mechanism

Electric fields in plasmas under pulsed currents

International Nuclear Information System (INIS)

Tsigutkin, K.; Doron, R.; Stambulchik, E.; Bernshtam, V.; Maron, Y.; Fruchtman, A.; Commisso, R. J.

2007-01-01

Electric fields in a plasma that conducts a high-current pulse are measured as a function of time and space. The experiment is performed using a coaxial configuration, in which a current rising to 160 kA in 100 ns is conducted through a plasma that prefills the region between two coaxial electrodes. The electric field is determined using laser spectroscopy and line-shape analysis. Plasma doping allows for three-dimensional spatially resolved measurements. The measured peak magnitude and propagation velocity of the electric field is found to match those of the Hall electric field, inferred from the magnetic-field front propagation measured previously

Simulation of plasma double-layer structures

International Nuclear Information System (INIS)

Borovsky, J.E.; Joyce, G.

1982-01-01

Electrostatic plasma double layers are numerically simulated by means of a magnetized 2 1/2-dimensional particle-in-cell method. The investigation of planar double layers indicates that these one-dimensional potential structures are susceptible to periodic disruption by instabilities in the low-potential plasmas. Only a slight increase in the double-layer thickness with an increase in its obliqueness to the magnetic field is observed. Weak magnetization results in the double-layer electric-field alignment of accelerated particles and strong magnetization results in their magnetic-field alignment. The numerial simulations of spatially periodic two-dimensional double layers also exhibit cyclical instability. A morphological invariance in two-dimensional double layers with respect to the degree of magnetization implies that the potential structures scale with Debye lengths rather than with gyroradii. Electron-beam excited electrostatic electron-cyclotron waves and (ion-beam driven) solitary waves are present in the plasmas adjacent to the double layers

Electric double layer and electrokinetic potential of pectic macromolecules in sugar beet

Directory of Open Access Journals (Sweden)

Kuljanin Tatjana A.

2008-01-01

Full Text Available Electrokinetic potential is an important property of colloidal particles and, regarding the fact that it is a well defined and easily measurable property, it is considered to be a permanent characteristic of a particular colloidal system. In fact, it is a measure of electrokinetic charge that surrounds the colloidal particle in a solution and is in direct proportion with the mobility of particles in an electric field. Gouy-Chapman-Stern-Graham's model of electric double layer was adopted and it was proven experimentally that the addition of Cu++ ions to sugar beet pectin caused a reduction in the negative electrokinetic potential proportional to the increase of Cu++ concentration. Higher Cu++ concentrations increased the proportion of cation specific adsorption (Cu++ and H+ with regard to electrostatic Coulombic forces. Consequently, there is a shift in the shear plane between the fixed and diffuse layers directed towards the diffuse layer, i.e. towards its compression and decrease in the electrokinetic potential or even charge inversion of pectin macromolecules.

Quasi-Static Electric Field Generator

Science.gov (United States)

Generazio, Edward R. (Inventor)

2017-01-01

A generator for producing an electric field for with an inspection technology system is provided. The generator provides the required variable magnitude quasi-static electric fields for the "illumination" of objects, areas and volumes to be inspected by the system, and produces human-safe electric fields that are only visible to the system. The generator includes a casing, a driven, non-conducting and triboelectrically neutral rotation shaft mounted therein, an ungrounded electrostatic dipole element which works in the quasi-static range, and a non-conducting support for mounting the dipole element to the shaft. The dipole element has a wireless motor system and a charging system which are wholly contained within the dipole element and the support that uses an electrostatic approach to charge the dipole element.

Parallel electric fields from ionospheric winds

International Nuclear Information System (INIS)

Nakada, M.P.

1987-01-01

The possible production of electric fields parallel to the magnetic field by dynamo winds in the E region is examined, using a jet stream wind model. Current return paths through the F region above the stream are examined as well as return paths through the conjugate ionosphere. The Wulf geometry with horizontal winds moving in opposite directions one above the other is also examined. Parallel electric fields are found to depend strongly on the width of current sheets at the edges of the jet stream. If these are narrow enough, appreciable parallel electric fields are produced. These appear to be sufficient to heat the electrons which reduces the conductivity and produces further increases in parallel electric fields and temperatures. Calculations indicate that high enough temperatures for optical emission can be produced in less than 0.3 s. Some properties of auroras that might be produced by dynamo winds are examined; one property is a time delay in brightening at higher and lower altitudes

Inductive electric field at the magnetopause

International Nuclear Information System (INIS)

Heikkila, W.J.

1982-01-01

The electric field data for two crossings of the magnetopause by ISEE-1 on November 20, 1977, have been analyzed with high time resolution. In both cases the electric field has a negative dawn-dusk component in the boundary layer, so it must reverse somewhere within the current layer to the positive value outside. If there is a component parallel to the moving magnetopause current it is small, and by no means obvious. In the case of the exit crossing from the boundary layer to the magnetosheath the data show that the electric field vector is turning for about two seconds at roughly the satellite spin rate; this changing direction suggests that the electric field has a curl. Such a curl could be caused by a travelling localized perturbation of the magnetopause surface current associated with impulsive plasma transport through the magnetopause

Modeling Electric Double-Layer Capacitors Using Charge Variation Methodology in Gibbs Ensemble

Directory of Open Access Journals (Sweden)

Ganeshprasad Pavaskar

2018-01-01

Full Text Available Supercapacitors deliver higher power than batteries and find applications in grid integration and electric vehicles. Recent work by Chmiola et al. (2006 has revealed unexpected increase in the capacitance of porous carbon electrodes using ionic liquids as electrolytes. The work has generated curiosity among both experimentalists and theoreticians. Here, we have performed molecular simulations using a recently developed technique (Punnathanam, 2014 for simulating supercapacitor system. In this technique, the two electrodes (containing electrolyte in slit pore are simulated in two different boxes using the Gibbs ensemble methodology. This reduces the number of particles required and interfacial interactions, which helps in reducing computational load. The method simulates an electric double-layer capacitor (EDLC with macroscopic electrodes with much smaller system sizes. In addition, the charges on individual electrode atoms are allowed to vary in response to movement of electrolyte ions (i.e., electrode is polarizable while ensuring these atoms are at the same electric potential. We also present the application of our technique on EDLCs with the electrodes modeled as slit pores and as complex three-dimensional pore networks for different electrolyte geometries. The smallest pore geometry showed an increase in capacitance toward the potential of 0 charge. This is in agreement with the new understanding of the electrical double layer in regions of dense ionic packing, as noted by Kornyshev’s theoretical model (Kornyshev, 2007, which also showed a similar trend. This is not addressed by the classical Gouy–Chapman theory for the electric double layer. Furthermore, the electrode polarizability simulated in the model improved the accuracy of the calculated capacitance. However, its addition did not significantly alter the capacitance values in the voltage range considered.

Study of electric field pulsation in helical plasmas

International Nuclear Information System (INIS)

Toda, S; Itoh, K

2011-01-01

A model for the experimental results of the periodic oscillation of the electric field, so-called the electric field pulsation, observed in the Compact Helical Device (Fujisawa et al 1998 Phys. Rev. Lett. 81 2256) and the Large Helical Device (Shimizu et al 2010 Plasma Fusion Res. 5 S1015) is presented. A self-generated oscillation of the radial electric field is shown as the simulation result in helical plasmas. The reduction of the anomalous transport diffusivity in the core region is observed due to the strong shear of the radial electric field when the positive electric field is shown in the core region in the periodic oscillation of E r . Two different time scales are found in the self-generated oscillation, which are the transport time scale and the fast time scale at the transition of the radial electric field. This oscillation because of the hysteresis characteristic is attributed to the electric field pulsation observed in helical plasmas. The parameter region of the condition for the self-generated oscillation is derived. It is shown that the multiple solutions of the radial electric field for the ambipolar condition are necessary but not sufficient for obtaining the self-generated oscillation.

The convection electric field in auroral substorms

DEFF Research Database (Denmark)

Gjerløv, Jesper Wittendorff; Hoffman, R.A.

2001-01-01

Dynamics Explorer 2 (DE 2) electric field and ion drift data are used in a statistical study of the ionospheric convection electric field in bulge-type auroral substorms. Thirty-one individual DE 2 substorm crossings were carefully selected and organized by the use of global auroral images obtained...... this database enabled us to compile a model of the ionospheric convection electric field. The characteristics of the premidnight convection reversal show a pronounced local time dependency. Far west of the surge it is a fairly well defined point reversal or convection shear. Approaching the surge and within...... the surge it is a region of weak electric fields increasing in width toward midnight that separates regions of equatorward and poleward electric fields. Therefore we adopt the term Harang region rather than the Harang discontinuity for the premidnight convection reversal. A relatively narrow convection...

High frequency electric field spikes formed by electron beam-plasma interaction in plasma density gradients

International Nuclear Information System (INIS)

Gunell, H.; Loefgren, T.

1997-02-01

In the electron beam-plasma interaction at an electric double layer the beam density is much higher than in the classical beam-plasma experiments. The wave propagation takes place along the density gradient, that is present at the high potential side of the double layer. Such a case is studied experimentally by injecting the electron beam from a plane cathode, without any grids suppressing the gradient, and by particle simulations. The high frequency field concentrates in a sharp 'spike' with a half width of the order of one wavelength. The spike is found to be a standing wave surrounded by regions dominated by propagating waves. It forms at a position where its frequency is close to the local plasma frequency. The spike forms also when the electric field is well below the threshold for modulational instability, and long before a density cavity is formed in the simulations. Particle simulations reveal that, at the spike, there is a backward travelling wave that, when it is strongly damped, accelerates electrons back towards the cathode. In a simulation of a homogeneous plasma without the density gradient no spike is seen, and the wave is purely travelling instead of standing. 9 refs

Analysis of the influence of the complex structure of clay hollow bricks on the values of electric field intensity by using the FDTD method

Directory of Open Access Journals (Sweden)

Choroszucho Agnieszka

2016-12-01

Full Text Available The study presents the analysis of the effects occurring at the propagation of electromagnetic waves within an area containing non-ideal, non-homogenous and absorbing dielectric. The analysed models are connected with housing constructions and include single and double-layered walls made of clay hollow bricks. The influence of the size of holes, the contained clay mass percentage and conductivity of brick on the distribution of electric field is presented. Double-layered wall causes more heterogeneity in distribution of electric field and numerous maxima and minima to compare with singlelayered construction. The presented results refer to the electromagnetic field generated by a wireless communication system (Wi-Fi, operating within the standard frequencies (2.4 GHz and 5 GHz. A FDTD method was used to the analysis of electric field distribution. Also in this paper all formulations of difference method (FDTD is presented. The possibilities of modifying the described method are indicated too. The obtained values of electric field intensity allow to determining the attenuation coefficient for different variants of the walls. Detailed analysis of influence of different types of building construction will make it possible to better understand the wave phenomena and counteract local fading at planning of wireless networks systems.

Radial electric fields for improved tokamak performance

International Nuclear Information System (INIS)

Downum, W.B.

1981-01-01

The influence of externally-imposed radial electric fields on the fusion energy output, energy multiplication, and alpha-particle ash build-up in a TFTR-sized, fusing tokamak plasma is explored. In an idealized tokamak plasma, an externally-imposed radial electric field leads to plasma rotation, but no charge current flows across the magnetic fields. However, a realistically-low neutral density profile generates a non-zero cross-field conductivity and the species dependence of this conductivity allows the electric field to selectively alter radial particle transport

Midday reversal of equatorial ionospheric electric field

Directory of Open Access Journals (Sweden)

R. G. Rastogi

1997-10-01

Full Text Available A comparative study of the geomagnetic and ionospheric data at equatorial and low-latitude stations in India over the 20 year period 1956–1975 is described. The reversal of the electric field in the ionosphere over the magnetic equator during the midday hours indicated by the disappearance of the equatorial sporadic E region echoes on the ionograms is a rare phenomenon occurring on about 1% of time. Most of these events are associated with geomagnetically active periods. By comparing the simultaneous geomagnetic H field at Kodaikanal and at Alibag during the geomagnetic storms it is shown that ring current decreases are observed at both stations. However, an additional westward electric field is superimposed in the ionosphere during the main phase of the storm which can be strong enough to temporarily reverse the normally eastward electric field in the dayside ionosphere. It is suggested that these electric fields associated with the V×Bz electric fields originate at the magnetopause due to the interaction of the solar wind and the interplanetary magnetic field.

Midday reversal of equatorial ionospheric electric field

Directory of Open Access Journals (Sweden)

R. G. Rastogi

Full Text Available A comparative study of the geomagnetic and ionospheric data at equatorial and low-latitude stations in India over the 20 year period 1956–1975 is described. The reversal of the electric field in the ionosphere over the magnetic equator during the midday hours indicated by the disappearance of the equatorial sporadic E region echoes on the ionograms is a rare phenomenon occurring on about 1% of time. Most of these events are associated with geomagnetically active periods. By comparing the simultaneous geomagnetic H field at Kodaikanal and at Alibag during the geomagnetic storms it is shown that ring current decreases are observed at both stations. However, an additional westward electric field is superimposed in the ionosphere during the main phase of the storm which can be strong enough to temporarily reverse the normally eastward electric field in the dayside ionosphere. It is suggested that these electric fields associated with the V×Bz electric fields originate at the magnetopause due to the interaction of the solar wind and the interplanetary magnetic field.

Supersymmetry for gauged double field theory and generalised Scherk–Schwarz reductions

International Nuclear Information System (INIS)

Berman, David S.; Lee, Kanghoon

2014-01-01

Previous constructions of supersymmetry for double field theory have relied on the so-called strong constraint. In this paper, the strong constraint is relaxed and the theory is shown to possess supersymmetry once the generalised Scherk–Schwarz reduction is imposed. The equivalence between the generalised Scherk–Schwarz reduced theory and the gauged double field theory is then examined in detail for the supersymmetric theory. As a biproduct we write the generalised Killing spinor equations for the supersymmetric double field theory

Electrical control of superparamagnetism

Science.gov (United States)

Yamada, Kihiro T.; Koyama, Tomohiro; Kakizakai, Haruka; Miwa, Kazumoto; Ando, Fuyuki; Ishibashi, Mio; Kim, Kab-Jin; Moriyama, Takahiro; Ono, Shimpei; Chiba, Daichi; Ono, Teruo

2017-01-01

The electric field control of superparamagnetism is realized using a Cu/Ni system, in which the deposited Ni shows superparamagnetic behavior above the blocking temperature. An electric double-layer capacitor (EDLC) with the Cu/Ni electrode and a nonmagnetic counter electrode is fabricated to examine the electric field effect on magnetism in the magnetic electrode. By changing the voltage applied to the EDLC, the blocking temperature of the system is clearly modulated.

Flow instability in laminar jet flames driven by alternating current electric fields

KAUST Repository

Kim, Gyeong Taek

2016-10-13

The effect of electric fields on the instability of laminar nonpremixed jet flames was investigated experimentally by applying the alternating current (AC) to a jet nozzle. We aimed to elucidate the origin of the occurrence of twin-lifted jet flames in laminar jet flow configurations, which occurred when AC electric fields were applied. The results indicated that a twin-lifted jet flame originated from cold jet instability, caused by interactions between negative ions in the jet flow via electron attachment as O +e→O when AC electric fields were applied. This was confirmed by conducting systematic, parametric experiment, which included changing gaseous component in jets and applying different polarity of direct current (DC) to the nozzle. Using two deflection plates installed in parallel with the jet stream, we found that only negative DC on the nozzle could charge oxygen molecules negatively. Meanwhile, the cold jet instability occurred only for oxygen-containing jets. A shedding frequency of jet stream due to AC driven instability showed a good correlation with applied AC frequency exhibiting a frequency doubling. However, for the applied AC frequencies over 80Hz, the jet did not respond to the AC, indicating an existence of a minimum flow induction time in a dynamic response of negative ions to external AC fields. Detailed regime of the instability in terms of jet velocity, AC voltage and frequency was presented and discussed. Hypothesized mechanism to explain the instability was also proposed.

Generation of Nonlinear Electric Field Bursts in the Outer Radiation Belt through Electrons Trapping by Oblique Whistler Waves

Science.gov (United States)

Agapitov, Oleksiy; Drake, James; Mozer, Forrest

2016-04-01

Huge numbers of different nonlinear structures (double layers, electron holes, non-linear whistlers, etc. referred to as Time Domain Structures - TDS) have been observed by the electric field experiment on board the Van Allen Probes. A large part of the observed non-linear structures are associated with whistler waves and some of them can be directly driven by whistlers. The parameters favorable for the generation of TDS were studied experimentally as well as making use of 2-D particle-in-cell (PIC) simulations for the system with inhomogeneous magnetic field. It is shown that an outward propagating front of whistlers and hot electrons amplifies oblique whistlers which collapse into regions of intense parallel electric field with properties consistent with recent observations of TDS from the Van Allen Probe satellites. Oblique whistlers seed the parallel electric fields that are driven by the beams. The resulting parallel electric fields trap and heat the precipitating electrons. These electrons drive spikes of intense parallel electric field with characteristics similar to the TDSs seen in the VAP data. The decoupling of the whistler wave and the nonlinear electrostatic component is shown in PIC simulation in the inhomogeneous magnetic field system. These effects are observed by the Van Allen Probes in the radiation belts. The precipitating hot electrons propagate away from the source region in intense bunches rather than as a smooth flux.

Electric field spikes formed by electron beam endash plasma interaction in plasma density gradients

International Nuclear Information System (INIS)

Gunell, H.; Loefgren, T.

1997-01-01

In the electron beam endash plasma interaction at an electric double layer the beam density is much higher than in the classical beam endash plasma experiments. The wave propagation takes place along the density gradient that is present at the high potential side of the double layer. Such a case is studied experimentally by injecting the electron beam from a plane cathode, without any grids suppressing the gradient, and by particle simulations. The high frequency field concentrates in a sharp open-quotes spikeclose quotes with a half width of the order of one wavelength. The spike is found to be a standing wave surrounded by regions dominated by propagating waves. It forms at a position where its frequency is close to the local plasma frequency. The spike forms also when the electric field is well below the threshold for modulational instability, and long before a density cavity is formed in the simulations. Particle simulations reveal that, at the spike, there is a backward traveling wave that, when it is strongly damped, accelerates electrons back towards the cathode. In a simulation of a homogeneous plasma without the density gradient no spike is seen, and the wave is purely travelling instead of standing. copyright 1997 American Institute of Physics

Electric field imaging of single atoms

Science.gov (United States)

Shibata, Naoya; Seki, Takehito; Sánchez-Santolino, Gabriel; Findlay, Scott D.; Kohno, Yuji; Matsumoto, Takao; Ishikawa, Ryo; Ikuhara, Yuichi

2017-01-01

In scanning transmission electron microscopy (STEM), single atoms can be imaged by detecting electrons scattered through high angles using post-specimen, annular-type detectors. Recently, it has been shown that the atomic-scale electric field of both the positive atomic nuclei and the surrounding negative electrons within crystalline materials can be probed by atomic-resolution differential phase contrast STEM. Here we demonstrate the real-space imaging of the (projected) atomic electric field distribution inside single Au atoms, using sub-Å spatial resolution STEM combined with a high-speed segmented detector. We directly visualize that the electric field distribution (blurred by the sub-Å size electron probe) drastically changes within the single Au atom in a shape that relates to the spatial variation of total charge density within the atom. Atomic-resolution electric field mapping with single-atom sensitivity enables us to examine their detailed internal and boundary structures. PMID:28555629

Magnetospheric electric fields and auroral oval

Science.gov (United States)

Laakso, Harri; Pedersen, Arne; Craven, John D.; Frank, L. A.

1992-01-01

DC electric field variations in a synchronous orbit (GEOS 2) during four substorms in the time sector 19 to 01 LT were investigated. Simultaneously, the imaging photometer on board DE 1 provided auroral images that are also utilized. Substorm onset is defined here as a sudden appearance of large electric fields. During the growth phase, the orientation of the electric field begins to oscillate some 30 min prior to onset. About 10 min before the onset GEOS 2 starts moving into a more tenuous plasma, probably due to a thinning of the current sheet. The onset is followed by a period of 10 to 15 min during which large electric fields occur. This interval can be divided into two intervals. During the first interval, which lasts 4 to 8 min, very large fields of 8 to 20 mV/m are observed, while the second interval contains relatively large fields (2 to 5 mV/m). A few min after the onset, the spacecraft returns to a plasma region of higher electron fluxes which are usually larger than before substorm. Some 30 min after onset, enhanced activity, lasting about 10 min, appears in the electric field. One of the events selected offers a good opportunity to study the formation and development of the Westward Traveling Surge (WST). During the traversal of the leading edge of the WTS (approximately 8 min) a stable wave mode at 5.7 mHz is detected.

Exceptionally High Electric Double Layer Capacitances of Oligomeric Ionic Liquids.

Science.gov (United States)

Matsumoto, Michio; Shimizu, Sunao; Sotoike, Rina; Watanabe, Masayoshi; Iwasa, Yoshihiro; Itoh, Yoshimitsu; Aida, Takuzo

2017-11-15

Electric double layer (EDL) capacitors are promising as next-generation energy accumulators if their capacitances and operation voltages are both high. However, only few electrolytes can simultaneously fulfill these two requisites. Here we report that an oligomeric ionic liquid such as IL4 TFSI with four imidazolium ion units in its structure provides a wide electrochemical window of ∼5.0 V, similar to monomeric ionic liquids. Furthermore, electrochemical impedance measurements using Au working electrodes demonstrated that IL4 TFSI exhibits an exceptionally high EDL capacitance of ∼66 μF/cm 2 , which is ∼6 times as high as those of monomeric ionic liquids so far reported. We also found that an EDL-based field effect transistor (FET) using IL4 TFSI as a gate dielectric material and SrTiO 3 as a channel material displays a very sharp transfer curve with an enhanced carrier accumulation capability of ∼64 μF/cm 2 , as determined by Hall-effect measurements.

Electrical and magnetic fields of the power supply

International Nuclear Information System (INIS)

2017-01-01

The availability of electrical energy in all areas of life is guaranteed by a widely ramified power grid. When electricity is transported, magnetic fields are created in addition to the electrical fields. In this brochure one will learn more about the causes and effects of electrical and magnetic fields as well as protection concepts and preventive measures. [de

Effect of AC electric fields on flame spread over electrical wire

KAUST Repository

Kim, Minkuk

2011-01-01

The effect of electric fields on the characteristics of flame spread over insulated electrical wire has been investigated experimentally by varying AC voltage and frequency applied to the wire in the normal gravity condition. The polyethylene (PE) insulated electrical wire was placed horizontally on electrically non-conducting posts and one end of the wire was connected to the high voltage terminal. Thus, the electrical system is the single electrode configuration. The wire was ignited at one end and the flame spread rate along the wire has been measured from the images using a video camera. Two distinct regimes existed depending on the applied AC frequency. In the low frequency regime, the flame spread rate decreased with the frequency and voltage. While in the high frequency regime, it decreased initially with voltage and then increased. At high frequency, the spread rate was even over that without applying electric fields. This result implies that fire safety codes developed without considering the effect of electric fields may require modifications. © 2010 Published by Elsevier Inc. on behalf of The Combustion Institute. All rights reserved.

The bee, the flower and the electric field

Directory of Open Access Journals (Sweden)

Robert Daniel

2016-01-01

Full Text Available Insects use several different senses to forage on flowers, and detect floral cues such as color, shape, pattern, humidity and chemical volatiles. This presentation will present our discovery of a previously unappreciated sensory capacity in bumblebees (Bombus terrestris: the detection of floral electric fields. We show that these floral fields act as informational cues, and that they can be affected by the visit of naturally electrically charged bees. Like visual cues, floral electric fields exhibit variations in pattern and structure, which can be discriminated by bumblebees. We also show that such electric field information contributes to the complex array of floral cues that together improve a pollinator’s memory of floral rewards. Floral electric fields arise from complex interactions with the surrounding atmosphere, an interaction between plants and their environment that not well understood. Because floral electric fields can change within seconds, this new sensory modality - electrostatic field detection- may facilitate rapid and dynamic communication between flowers and their pollinators.

Electric Potential and Electric Field Imaging with Dynamic Applications & Extensions

Science.gov (United States)

Generazio, Ed

2017-01-01

The technology and methods for remote quantitative imaging of electrostatic potentials and electrostatic fields in and around objects and in free space is presented. Electric field imaging (EFI) technology may be applied to characterize intrinsic or existing electric potentials and electric fields, or an externally generated electrostatic field made be used for volumes to be inspected with EFI. The baseline sensor technology (e-Sensor) and its construction, optional electric field generation (quasi-static generator), and current e- Sensor enhancements (ephemeral e-Sensor) are discussed. Critical design elements of current linear and real-time two-dimensional (2D) measurement systems are highlighted, and the development of a three dimensional (3D) EFI system is presented. Demonstrations for structural, electronic, human, and memory applications are shown. Recent work demonstrates that phonons may be used to create and annihilate electric dipoles within structures. Phonon induced dipoles are ephemeral and their polarization, strength, and location may be quantitatively characterized by EFI providing a new subsurface Phonon-EFI imaging technology. Results from real-time imaging of combustion and ion flow, and their measurement complications, will be discussed. Extensions to environment, Space and subterranean applications will be presented, and initial results for quantitative characterizing material properties are shown. A wearable EFI system has been developed by using fundamental EFI concepts. These new EFI capabilities are demonstrated to characterize electric charge distribution creating a new field of study embracing areas of interest including electrostatic discharge (ESD) mitigation, manufacturing quality control, crime scene forensics, design and materials selection for advanced sensors, combustion science, on-orbit space potential, container inspection, remote characterization of electronic circuits and level of activation, dielectric morphology of

Electric field measurements in a near atmospheric pressure nanosecond pulse discharge with picosecond electric field induced second harmonic generation

Science.gov (United States)

Goldberg, Benjamin M.; Chng, Tat Loon; Dogariu, Arthur; Miles, Richard B.

2018-02-01

We present an optical electric field measurement method for use in high pressure plasma discharges. The method is based upon the field induced second harmonic generation technique and can be used for localized electric field measurements with sub-nanosecond resolution in any gaseous species. When an external electric field is present, a dipole is induced in the typically centrosymmetric medium, allowing for second harmonic generation with signal intensities which scale by the square of the electric field. Calibrations have been carried out in 100 Torr room air, and a minimum sensitivity of 450 V/cm is demonstrated. Measurements were performed with nanosecond or faster temporal resolution in a 100 Torr room air environment both with and without a plasma present. It was shown that with no plasma present, the field follows the applied voltage to gap ratio, as measured using the back current shunt method. When the electric field is strong enough to exceed the breakdown threshold, the measured field was shown to exceed the anticipated voltage to gap ratio which is taken as an indication of the ionization wave front as it sweeps through the plasma volume.

End-shorting and electric field in edge plasmas with application to field-reversed configurations

International Nuclear Information System (INIS)

Steinhauer, Loren C.

2002-01-01

The shorting of open field lines where they intersect external boundaries strongly modifies the transverse electric field all along the field lines. The modified electric field is found by an extension of the familiar Boltzmann relation for the electric potential. This leads to a prediction of the electric drift. Flow generation by electrical shorting is applied here to three aspects of elongated field-reversed configurations: plasma rotation rate; the particle-loss spin-up mechanism; and the sustainability of the rotating magnetic field current drive method

Electrical double layer at various electrode potentials: A modification by vibration

Czech Academy of Sciences Publication Activity Database

Zhan, H.; Červenka, Jiří; Prawer, S.; Garrett, D.J.

2017-01-01

Roč. 121, č. 8 (2017), s. 4760-4764 ISSN 1932-7447 Institutional support: RVO:68378271 Keywords : electrical double layer * vibration * high concentration * model Subject RIV: CF - Physical ; Theoretical Chemistry OBOR OECD: Physical chemistry Impact factor: 4.536, year: 2016

Plasma Flows in Crossed Magnetic and Electric Fields

International Nuclear Information System (INIS)

Belikov, A.G.

2005-01-01

The effect of the magnitude and direction of an external electric field on the plasma flowing through a magnetic barrier is studied by numerically solving two-fluid MHD equations. The drift velocity of the plasma flow and the distribution of the flow electrons over transverse velocities are found to depend on the magnitude and direction of the electric field. It is shown that the direction of the induced longitudinal electric field is determined by the direction of the external field and that the electric current generated by the plasma flow significantly disturbs the barrier field

Electrically induced magnetic fields; a consistent approach

Science.gov (United States)

Batell, Brian; Ferstl, Andrew

2003-09-01

Electromagnetic radiation exists because changing magnetic fields induce changing electric fields and vice versa. This fact often appears inconsistent with the way some physics textbooks solve particular problems using Faraday's law. These types of problems often ask students to find the induced electric field given a current that does not vary linearly with time. A typical example involves a long solenoid carrying a sinusoidal current. This problem is usually solved as an example or assigned as a homework exercise. The solution offered by many textbooks uses the approximation that the induced, changing electric field produces a negligible magnetic field, which is only valid at low frequencies. If this approximation is not explicitly acknowledged, then the solution appears inconsistent with the description of electromagnetic radiation. In other cases, when the problem is solved without this approximation, the electric and magnetic fields are derived from the vector potential. We present a detailed calculation of the electric and magnetic fields inside and outside the long solenoid without using the vector potential. We then offer a comparison of our solution and a solution given in an introductory textbook.

Multisubband electron mobility in a parabolic quantum well structure under the influence of an applied electric field

International Nuclear Information System (INIS)

Sahoo, N.; Sahu, T.

2014-01-01

We study the multisubband electron mobility in a barrier delta doped Al x Ga 1−x As parabolic quantum well structure under the influence of an applied electric field perpendicular to the interface plane. We consider the alloy fraction x = 0.3 for barriers and vary x from 0.0 to 0.1 for the parabolic well. Electrons diffuse into the well and confine within the triangular like potentials near the interfaces due to Coulomb interaction with ionized donors. The parabolic structure potential, being opposite in nature, partly compensates the Coulomb potential. The external electric field further amends the potential structure leading to an asymmetric potential profile. Accordingly the energy levels, wave functions and occupation of subbands change. We calculate low temperature electron mobility as a function of the electric field and show that when two subbands are occupied, the mobility is mostly dominated by ionised impurity scattering mediated by intersubband effects. As the field increases transition from double subband to single subband occupancy occurs. A sudden enhancement in mobility is obtained due to curtailment of intersubband effects. Thereafter the mobility is governed by both impurity and alloy disorder scatterings. Our analysis of mobility as a function of the electric field for different structural parameters shows interesting results. (semiconductor physics)

The quantum double in integrable quantum field theory

International Nuclear Information System (INIS)

Bernard, D.; LeClair, A.

1993-01-01

Various aspects of recent works on affine quantum group symmetry of integrable 2D quantum field theory are reviewed and further clarified. A geometrical meaning is given to the quantum double, and other properties of quantum groups. The S-matrix is identified with the universal R-matrix. Multiplicative presentations of the yangian double are analyzed. (orig.)

Electric Field Effects in RUS Measurements

Energy Technology Data Exchange (ETDEWEB)

Darling, Timothy W [Los Alamos National Laboratory; Ten Cate, James A [Los Alamos National Laboratory; Allured, Bradley [UNIV NEVADA, RENO; Carpenter, Michael A [CAMBRIDGE UNIV. UK

2009-09-21

Much of the power of the Resonant Ultrasound Spectroscopy (RUS) technique is the ability to make mechanical resonance measurements while the environment of the sample is changed. Temperature and magnetic field are important examples. Due to the common use of piezoelectric transducers near the sample, applied electric fields introduce complications, but many materials have technologically interesting responses to applied static and RF electric fields. Non-contact optical, buffered, or shielded transducers permit the application of charge and externally applied electric fields while making RUS measurements. For conducting samples, in vacuum, charging produces a small negative pressure in the volume of the material - a state rarely explored. At very high charges we influence the electron density near the surface so the propagation of surface waves and their resonances may give us a handle on the relationship of electron density to bond strength and elasticity. Our preliminary results indicate a charge sign dependent effect, but we are studying a number of possible other effects induced by charging. In dielectric materials, external electric fields influence the strain response, particularly in ferroelectrics. Experiments to study this connection at phase transformations are planned. The fact that many geological samples contain single crystal quartz suggests a possible use of the piezoelectric response to drive vibrations using applied RF fields. In polycrystals, averaging of strains in randomly oriented crystals implies using the 'statistical residual' strain as the drive. The ability to excite vibrations in quartzite polycrystals and arenites is explored. We present results of experimental and theoretical approaches to electric field effects using RUS methods.

Numerical Study of Electric Field Enhanced Combustion

KAUST Repository

Han, Jie

2016-12-26

Electric fields can be used to change and control flame properties, for example changing flame speed, enhancing flame stability, or reducing pollutant emission. The ions generated in flames are believed to play the primary role. Although experiments have been carried out to study electric field enhanced combustion, they are not sufficient to explain how the ions in a flame are affected by an electric field. It is therefore necessary to investigate the problem through numerical simulations. In the present work, the electric structure of stabilized CH4/air premixed flames at atmospheric pressure within a direct current field is studied using numerical simulations. This study consists of three parts. First, the transport equations are derived from the Boltzmann kinetic equation for each individual species. Second, a general method for computing the diffusivity and mobility of ions in a gas mixture is introduced. Third, the mechanisms for neutral and charged species are improved to give better predictions of the concentrations of charged species, based on experimental data. Following from this, comprehensive numerical results are presented, including the concentrations and fluxes of charged species, the distributions of the electric field and electric potential, and the electric current-voltage relation. Two new concepts introduced with the numerical results are the plasma sheath and dead zone in the premixed flame. A reactive plasma sheath and a Boltzmann relation sheath are discovered in the region near the electrodes. The plasma sheath penetrates into the flame gas when a voltage is applied, and penetrating further if the voltage is higher. The zone outside the region of sheath penetration is defined as the dead zone. With the two concepts, analytical solutions for the electric field, electric potential and current-voltage curve are derived. The solutions directly describe the electric structure of a premixed flame subject to a DC field. These analytical solutions

Electric field induced instabilities in free emulsion films

Energy Technology Data Exchange (ETDEWEB)

Tchoukov, P.; Dabros, T. [Natural Resources Canada, Devon, AB (Canada); Mostowfi, F. [Schlumberger DBR Technology Center, Edmonton, AB (Canada); Panchev, N. [Champion Technologies Inc., Houston, TX (United States); Czarnecki, J. [Alberta Univ., Edmonton, AB (Canada). Dept. of Chemical and Materials Engineering

2009-07-01

This presentation reported on a study that investigated the mechanism of electric field-induced breakdown of free emulsion films. Instability patterns were observed on the plane of a water-oil-water film following electric polarization. The length-scales of the instabilities were measured by analyzing images immediately after applying the electric field. Linear stability analysis was used to calculate the theoretical dominant wavelengths. The calculated values were found to be in good agreement with measured values. The films were formed in a thin film apparatus modified so that the oil film separated 2 aqueous phase compartments, each in contact with a platinum electrode. This enabled the measurement of disjoining pressure while applying the electric field to the film. It was concluded that breakdown of thin films induced by electric field has many applications, including electrostatic de-emulsification/desalination of crude oil and emulsion stability measurements. It was concluded that electroporation and dielectric breakdown may be responsible for electric field-induced breakdown. This study also presented evidence of an increase in electric field-induced instabilities in emulsion films resulting in rupture. tabs., figs.

Hofstadter spectrum in electric and magnetic fields

International Nuclear Information System (INIS)

Kunold, Alejandro; Torres, Manuel

2005-01-01

The problem of Bloch electrons in two dimensions subjected to magnetic and intense electric fields is investigated. Magnetic translations, electric evolution, and energy translation operators are used to specify the solutions of the Schroedinger equation. For rational values of the magnetic flux quanta per unit cell and commensurate orientations of the electric field relative to the original lattice, an extended superlattice can be defined and a complete set of mutually commuting space-time symmetry operators is obtained. Dynamics of the system is governed by a finite difference equation that exactly includes the effects of: an arbitrary periodic potential, an electric field orientated in a commensurable direction of the lattice, and coupling between Landau levels. A weak periodic potential broadens each Landau level in a series of minibands, separated by the corresponding minigaps. The addition of the electric field induces a series of avoided and exact crossing of the quasienergies, for sufficiently strong electric field the spectrum evolves into equally spaced discreet levels, in this 'magnetic Stark ladder' the energy separation is an integer multiple of hE/aB, with a the lattice parameter

A double layer review

International Nuclear Information System (INIS)

Block, L.P.

1977-06-01

A review of the main results on electrostatic double layers (sometimes called space charge layers or sheaths) obtained from theory, and laboratory and space experiments up to the spring of 1977 is given. By means of barium jets and satellite probes, double layers have now been found at the altitudes, earlier predicted theoretically. The general potential distribution above the auroral zone, suggested by inverted V-events and electric field reversals, is corroborated. (author)

Machine Vision System for Characterizing the Electric Field for the 225 Ra EDM Experiment

Science.gov (United States)

Sanchez, Andrew

2017-09-01

If an atom or fundamental particle possesses an electric dipole moment (EDM), that would imply time-reversal violation. At our current capability, if an EDM is detected in such a particle, that would suggest the discovery of beyond the standard model (BSM) physics. The unique structure of 225 Ra makes its atomic EDM favorable in the BSM search. An upgraded Ra-EDM apparatus will increase experimental sensitivity and the target electric field of 150 kV/cm will more than double the electric field used in previous experiments. To determine the electric field, the potential difference and electrode separation distance must be known. The optical method I have developed is a high-precision, non-invasive technique to measure electrode separation without making contact with the sensitive electrode surfaces. A digital camera utilizes a bi-telecentric lens to reduce parallax error and produce constant magnification throughout the optical system, regardless of object distance. A monochrome LED backlight enhances sharpness of the electrode profile, reducing uncertainty in edge determination and gap width. A program utilizing an edge detection algorithm allows precise, repeatable measurement of the gap width to within 1% and measurement of the relative angle of the electrodes. This work (SAM, Ra EDM) is supported by Michigan State University. This work (REU Program) is supported by U.S. National Science Foundation under Grant Number #1559866.

Effect of the averaging volume and algorithm on the in situ electric field for uniform electric- and magnetic-field exposures

International Nuclear Information System (INIS)

Hirata, Akimasa; Takano, Yukinori; Fujiwara, Osamu; Kamimura, Yoshitsugu

2010-01-01

The present study quantified the volume-averaged in situ electric field in nerve tissues of anatomically based numeric Japanese male and female models for exposure to extremely low-frequency electric and magnetic fields. A quasi-static finite-difference time-domain method was applied to analyze this problem. The motivation of our investigation is that the dependence of the electric field induced in nerve tissue on the averaging volume/distance is not clear, while a cubical volume of 5 x 5 x 5 mm 3 or a straight-line segment of 5 mm is suggested in some documents. The influence of non-nerve tissue surrounding nerve tissue is also discussed by considering three algorithms for calculating the averaged in situ electric field in nerve tissue. The computational results obtained herein reveal that the volume-averaged electric field in the nerve tissue decreases with the averaging volume. In addition, the 99th percentile value of the volume-averaged in situ electric field in nerve tissue is more stable than that of the maximal value for different averaging volume. When including non-nerve tissue surrounding nerve tissue in the averaging volume, the resultant in situ electric fields were not so dependent on the averaging volume as compared to the case excluding non-nerve tissue. In situ electric fields averaged over a distance of 5 mm were comparable or larger than that for a 5 x 5 x 5 mm 3 cube depending on the algorithm, nerve tissue considered and exposure scenarios. (note)

Vacuum instability in a random electric field

International Nuclear Information System (INIS)

Krive, I.V.; Pastur, L.A.

1984-01-01

The reaction of the vacuum on an intense spatially homogeneous random electric field is investigated. It is shown that a stochastic electric field always causes a breakdown of the boson vacuum, and the number of pairs of particles which are created by the electric field increases exponentially in time. For the choice of potential field in the form of a dichotomic random process we find in explicit form the dependence of the average number of pairs of particles on the time of the action of the source of the stochastic field. For the fermion vacuum the average number of pairs of particles which are created by the field in the lowest order of perturbation theory in the amplitude of the random field is independent of time

Electric and magnetic fields in medicine and biology

International Nuclear Information System (INIS)

Anon.

1985-01-01

Papers Include: The effects of low frequency (50 Hz) magnetic fields on neuro-chemical transmission in vitro; Morphological changes in E Coli subjected to DC electrical fields; An investigation of some claimed biological effects of electromagnetic fields; Electrical phenomena and bone healing - a comparison of contemporary techniques; Clinical evaluations of a portable module emitting pulsed RF energy; The design, construction and performance of a magnetic nerve stimulator; The principle of electric field tomography and its application to selective read-out of information from peripheral nerves; Applied potential tomography - clinical applications; Impendance imaging using a linear electrode array; Mathematics as an aid to experiment: human body currents induced by power frequency electric fields; Effects of electric field near 750KV transmission line and protection against their harmful consequences; Leukemia and electromagnetic fields: a case-control study; Overhead power lines and childhood cancer; Magnetic measurement of nerve action currents - a new intraoperative recording technique; The potential use of electron spin resonance or impedance measurement to image neuronal electrical activity in the human brain

The induced electric field distribution in the solar atmosphere

International Nuclear Information System (INIS)

Chen Rong; Yang Zhi-Liang; Deng Yuan-Yong

2013-01-01

A method of calculating the induced electric field is presented. The induced electric field in the solar atmosphere is derived by the time variation of the magnetic field when the accumulation of charged particles is neglected. In order to derive the spatial distribution of the magnetic field, several extrapolation methods are introduced. With observational data from the Helioseismic and Magnetic Imager aboard NASA's Solar Dynamics Observatory taken on 2010 May 20, we extrapolate the magnetic field from the photosphere to the upper atmosphere. By calculating the time variation of the magnetic field, we can get the induced electric field. The derived induced electric field can reach a value of 10 2 V cm −1 and the average electric field has a maximum point at the layer 360 km above the photosphere. The Monte Carlo method is used to compute the triple integration of the induced electric field.

Conditions for double layers in the Earth's magnetosphere and perhaps in other astrophysical objects

International Nuclear Information System (INIS)

Lyons, L.R.

1987-01-01

Double layers (i.e., electric fields parallel to B) form along auroral field lines in the Earth's magnetosphere. They form in order to maintain current continuity in the ionosphere in the presence of a magnetospheric electric field E with DEL.E not= O. Features which govern the formation of the double layers are: 1) the divergence of E; 2) the conductivity of the ionosphere; and 3) the current-voltage characteristics of auroral magnetic field lines. Astrophysical situations where DEL.E not= O is applied to a conducting plasma similar to the Earth's ionosphere are potential candidates for the formation of double layers. The region with DEL.E not= O can be generated within, or along field lines connected to, the conducting plasma. In addition to DEL.E, shear neutral flow in the conducting plasma can also form double layers. (author)

Global effects of double layers

International Nuclear Information System (INIS)

Raad, M.A.

1984-12-01

Locally the formation of an electrostatic double layer in a current carrying plasma leads to a direct acceleration of particles which may penetrate far into the surrounding medium. The potential across the double layer, giving this acceleration, must be maintained by the external system and is a basic parameter for the local to global coupling. The double layer potential is associated with an electric field parallel to the magnetic field. In general this leads to a magnetohydrodynamic relaxation of the surrounding medium providing the influx of energy which is dissipated by the double layer. The double layer potential is limited as is the maximum possible rate of energy influx. If the global response of the external medium can be represented by an external circuit and if an equivalent circuit element can be found to represent the double layer, for example a negative resistance for intermediate time scales, it is possible to give a description of the dynamics and stability of the whole system. (Author)

Theory of the formation of the electric double layer at the ion exchange membrane-solution interface.

Science.gov (United States)

Moya, A A

2015-02-21

This work aims to extend the study of the formation of the electric double layer at the interface defined by a solution and an ion-exchange membrane on the basis of the Nernst-Planck and Poisson equations, including different values of the counter-ion diffusion coefficient and the dielectric constant in the solution and membrane phases. The network simulation method is used to obtain the time evolution of the electric potential, the displacement electric vector, the electric charge density and the ionic concentrations at the interface between a binary electrolyte solution and a cation-exchange membrane with total co-ion exclusion. The numerical results for the temporal evolution of the interfacial electric potential and the surface electric charge are compared with analytical solutions derived in the limit of the shortest times by considering the Poisson equation for a simple cationic diffusion process. The steady-state results are justified from the Gouy-Chapman theory for the diffuse double layer in the limits of similar and high bathing ionic concentrations with respect to the fixed-charge concentration inside the membrane. Interesting new physical insights arise from the interpretation of the process of the formation of the electric double layer at the ion exchange membrane-solution interface on the basis of a membrane model with total co-ion exclusion.

Electric field enhancement of electron emission rates from Z1/2 centers in 4H-SiC

International Nuclear Information System (INIS)

Evwaraye, A. O.; Smith, S. R.; Mitchel, W. C.; Farlow, G. C.

2009-01-01

Z 1/2 defect centers were produced by irradiating 4H-SiC bulk samples with 1 MeV electrons at room temperature. The emission rate dependence on the electric field in the depletion region was measured using deep level transient spectroscopy and double-correlation deep level transient spectroscopy. It is found that the Z 1/2 defect level shows a strong electric field dependence with activation energy decreasing from E c -0.72 eV at zero field to E c -0.47 eV at 6.91x10 5 V/cm. The phonon assisted tunneling model of Karpus and Perel [Sov. Phys. JETP 64, 1376 (1986)] completely describes the experimental data. This model describes the dependence of the emission rate on electric field F as e n (F)=e no exp(F 2 /F c 2 ), where F c is the characteristic field that depends on the phonon assisted tunneling time τ 2 . The values of F c and τ 2 were determined and the analysis of the data leads to the suggestion that Z 1/2 may be a substitutional point defect.

Moderate and high intensity pulsed electric fields

OpenAIRE

Timmermans, Rian Adriana Hendrika

2018-01-01

Pulsed Electric Field (PEF) processing has gained a lot of interest the last decades as mild processing technology as alternative to thermal pasteurisation, and is suitable for preservation of liquid food products such as fruit juices. PEF conditions typically applied at industrial scale for pasteurisation are high intensity pulsed electric fields aiming for minimal heat load, with an electric field strength (E) in the range of 15 − 20 kV/cm and pulse width (τ) between 2 − 20 μs. Alternativel...

Interaction between lf electric fields and biological bodies

Directory of Open Access Journals (Sweden)

Češelkoska Vesna C.

2004-01-01

Full Text Available In this paper the Equivalent electrodes method is used for electric field calculation in the proximity of the various biological subjects exposed to an electric field in the LF range. Several results of the electric field intensity on the body surface and numerous graphical results for equipotential and equienergetic curves are presented.

Remote sensing of mesospheric electric fields using MF radars

Science.gov (United States)

Meek, C. E.; Manson, A. H.; Martynenko, S. I.; Rozumenko, V. T.; Tyrnov, O. F.

2004-07-01

Large mesospheric electric fields can play an essential role in middle atmospheric electrodynamics (see, e.g., Goldberg, R. A., Middle Atmospheric Electrodynamics during MAP, Adv. Space Res. 10 (10) (1990) 209). The V/m electric fields of atmospheric origin can be the possible cause of large variations in the electron collision frequency at mesospheric altitudes, and this provides a unique opportunity to take measurements of electric fields in the lower ionosphere by using remote sensing instruments employing radiowave techniques. A technique has been proposed for making estimates of large mesospheric electric field intensities on the lower edge of the ionosphere by using MF radar data and the inherent effective electron collision frequency. To do this, data collected in Canada and Ukraine were utilized. The developed technique permits the changes in mesospheric electric field intensities to be derived from MF radar data in real time. The statistical analysis of data consistent with large mesospheric electric field intensities in the 60-67km region resulted in the following inferences. There are at least two mechanisms for the generation of large mesospheric electric fields in the mesosphere. The most likely mechanism, with a probability of 60-70%, is the summation of random fields from a large number of elementary small-scale mesospheric generators, which results in a one-parameter Rayleigh distribution of the total large mesospheric electric field intensity E with a mean value of approximately 0.7-0.9V/m in the 60-67km altitude region, or in the corresponding one-parameter exponential distribution of the intensity squared E2 of large mesospheric electric fields. The second mechanism of unknown nature, with 5-15% probability, gives rise to the sporadic appearance of large mesospheric electric field intensities E>2.5V/m with a mean of 4V/m. Statistically significant seasonal differences in the averaged large mesospheric electric field parameters have not been

Microstickies agglomeration by electric field.

Science.gov (United States)

Du, Xiaotang Tony; Hsieh, Jeffery S

2016-01-01

Microstickies deposits on both paper machine and paper products when it agglomerates under step change in ionic strength, pH, temperature and chemical additives. These stickies increase the down time of the paper mill and decrease the quality of paper. The key property of microstickies is its smaller size, which leads to low removal efficiency and difficulties in measurement. Thus the increase of microstickies size help improve both removal efficiency and reduce measurement difficulty. In this paper, a new agglomeration technology based on electric field was investigated. The electric treatment could also increase the size of stickies particles by around 100 times. The synergetic effect between electric field treatment and detacky chemicals/dispersants, including polyvinyl alcohol, poly(diallylmethylammonium chloride) and lignosulfonate, was also studied.

Crystal growth under external electric fields

International Nuclear Information System (INIS)

Uda, Satoshi; Koizumi, Haruhiko; Nozawa, Jun; Fujiwara, Kozo

2014-01-01

This is a review article concerning the crystal growth under external electric fields that has been studied in our lab for the past 10 years. An external field is applied electrostatically either through an electrically insulating phase or a direct injection of an electric current to the solid-interface-liquid. The former changes the chemical potential of both solid and liquid and controls the phase relationship while the latter modifies the transport and partitioning of ionic solutes in the oxide melt during crystallization and changes the solute distribution in the crystal

Crystal growth under external electric fields

Energy Technology Data Exchange (ETDEWEB)

Uda, Satoshi; Koizumi, Haruhiko; Nozawa, Jun; Fujiwara, Kozo [Institute for Materials Research, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai, Miyagi 980-8577 (Japan)

2014-10-06

This is a review article concerning the crystal growth under external electric fields that has been studied in our lab for the past 10 years. An external field is applied electrostatically either through an electrically insulating phase or a direct injection of an electric current to the solid-interface-liquid. The former changes the chemical potential of both solid and liquid and controls the phase relationship while the latter modifies the transport and partitioning of ionic solutes in the oxide melt during crystallization and changes the solute distribution in the crystal.

Electric field measurements in high pressure discharges

International Nuclear Information System (INIS)

Mitko, S.V.; Ochkin, V.N.; Serdyuchenko, A.Yu.; Tskhai, S.N.

2001-01-01

Electric fields define a wide range of interactions and phenomena at different phases of matter both on micro- and macro-level. Investigation of electric fields behavior provides a key for understanding of these phenomena and their application

Manipulation of positron orbits in a dipole magnetic field with fluctuating electric fields

Science.gov (United States)

Saitoh, H.; Horn-Stanja, J.; Nißl, S.; Stenson, E. V.; Hergenhahn, U.; Pedersen, T. Sunn; Singer, M.; Dickmann, M.; Hugenschmidt, C.; Stoneking, M. R.; Danielson, J. R.; Surko, C. M.

2018-01-01

We report the manipulation of positron orbits in a toroidal dipole magnetic field configuration realized with electric fields generated by segmented electrodes. When the toroidal circulation motion of positrons in the dipole field is coupled with time-varying electric fields generated by azimuthally segmented outer electrodes, positrons undergo oscillations of their radial positions. This enables quick manipulation of the spatial profiles of positrons in a dipole field trap by choosing appropriate frequency, amplitude, phase, and gating time of the electric fields. According to numerical orbit analysis, we applied these electric fields to positrons injected from the NEPOMUC slow positron facility into a prototype dipole field trap experiment with a permanent magnet. Measurements with annihilation γ-rays clearly demonstrated the efficient compression effects of positrons into the strong magnetic field region of the dipole field configuration. This positron manipulation technique can be used as one of essential tools for future experiments on the formation of electron-positron plasmas.

High electric field conduction in low-alkali boroaluminosilicate glass

Science.gov (United States)

Dash, Priyanka; Yuan, Mengxue; Gao, Jun; Furman, Eugene; Lanagan, Michael T.

2018-02-01

Electrical conduction in silica-based glasses under a low electric field is dominated by high mobility ions such as sodium, and there is a transition from ionic transport to electronic transport as the electric field exceeds 108 V/m at low temperatures. Electrical conduction under a high electric field was investigated in thin low-alkali boroaluminosilicate glass samples, showing nonlinear conduction with the current density scaling approximately with E1/2, where E is the electric field. In addition, thermally stimulated depolarization current (TSDC) characterization was carried out on room-temperature electrically poled glass samples, and an anomalous discharging current flowing in the same direction as the charging current was observed. High electric field conduction and TSDC results led to the conclusion that Poole-Frenkel based electronic transport occurs in the mobile-cation-depleted region adjacent to the anode, and accounts for the observed anomalous current.

Control of the radial electric field shear by modification of the magnetic field configuration in LHD

International Nuclear Information System (INIS)

Ida, K.; Yoshinuma, M.; Yokoyama, M.

2005-01-01

Control of the radial electric field, E r , is considered to be important in helical plasmas, because the radial electric field and its shear are expected to reduce neoclassical and anomalous transport, respectively. In general, the radial electric field can be controlled by changing the collisionality, and positive or negative electric fields have been obtained by decreasing or increasing the electron density, respectively. Although the sign of the radial electric field can be controlled by changing the collisionality, modification of the magnetic field is required to achieve further control of the radial electric field, especially to produce a strong radial electric field shear. In the Large Helical Device (LHD) the radial electric field profiles are shown to be controlled by the modification of the magnetic field by (1) changing the radial profile of the effective helical ripples, ε h (2) creating a magnetic island with an external perturbation field coil and (3) changing the local island divertor coil current

Control of the radial electric field shear by modification of the magnetic field configuration in LHD

International Nuclear Information System (INIS)

Ida, K.; Yoshinuma, M.; Yokoyama, M.

2005-01-01

Control of the radial electric field, E γ , is considered to be important in helical plasmas, because the radial electric field and its shear are expected to reduce neoclassical and anomalous transport, respectively. In general, the radial electric field can be controlled by changing the collisionality, and positive or negative electric field have been obtained by decreasing or increasing the electron density, respectively. Although the sign of the radial electric field can be controlled by changing the collisionality, modification of the magnetic field is required to achieve further control of the radial electric field, especially producing a strong radial electric field shear. In the Large Helical Device (LHD) the radial electric field profiles are shown to be controlled by the modification of the magnetic field by 1) changing the radial profile of the helical ripples, ε h , 2) creating a magnetic island with an external perturbation field coil and 3) changing the local island divertor coil current. (author)

Enhanced electrical conductivity in graphene and boron nitride nanoribbons in large electric fields

Science.gov (United States)

Chegel, Raad

2018-02-01

Based on data of density function theory (DFT) as the input of tight binding model, the electrical conductivity (σ(T)) of graphene nanoribbos (GNRs) and Boron Nitride nanoribbos (BNNRs) under external electric fields with different wide are studied using the Green's function method. The BNNRs are wide band gap semiconductor and they are turned into metal depending on their electric field strength. The σ(T) shows increasing in low temperature region and after reaching the maximum value, it will decrease in high temperature region. In lower temperature ranges, the electrical conductivity of the GNRs is greater than that of the BNNRs. In a low temperature region, the σ(T) of GNRs increases linearly with temperature unlike the BNNRs. The electrical conductivity are strongly dependent on the electric field strength.

A corotation electric field model of the Earth derived from Swarm satellite magnetic field measurements

Science.gov (United States)

Maus, Stefan

2017-08-01

Rotation of the Earth in its own geomagnetic field sets up a primary corotation electric field, compensated by a secondary electric field of induced electrical charges. For the geomagnetic field measured by the Swarm constellation of satellites, a derivation of the global corotation electric field inside and outside of the corotation region is provided here, in both inertial and corotating reference frames. The Earth is assumed an electrical conductor, the lower atmosphere an insulator, followed by the corotating ionospheric E region again as a conductor. Outside of the Earth's core, the induced charge is immediately accessible from the spherical harmonic Gauss coefficients of the geomagnetic field. The charge density is positive at high northern and southern latitudes, negative at midlatitudes, and increases strongly toward the Earth's center. Small vertical electric fields of about 0.3 mV/m in the insulating atmospheric gap are caused by the corotation charges located in the ionosphere above and the Earth below. The corotation charges also flow outward into the region of closed magnetic field lines, forcing the plasmasphere to corotate. The electric field of the corotation charges further extends outside of the corotating regions, contributing radial outward electric fields of about 10 mV/m in the northern and southern polar caps. Depending on how the magnetosphere responds to these fields, the Earth may carry a net electric charge.

Effects of geomagnetic activity on the mesospheric electric fields

Directory of Open Access Journals (Sweden)

A. M. Zadorozhny

1998-12-01

Full Text Available The results of three series of rocket measurements of mesospheric electric fields carried out under different geomagnetic conditions at polar and high middle latitudes are analysed. The measurements show a clear dependence of the vertical electric fields on geomagnetic activity at polar and high middle latitudes. The vertical electric fields in the lower mesosphere increase with the increase of geomagnetic indexes Kp and ∑Kp. The simultaneous increase of the vertical electric field strength and ion conductivity was observed in the mesosphere during geomagnetic disturbances. This striking phenomenon was displayed most clearly during the solar proton events of October, 1989 accompanied by very strong geomagnetic storm (Kp=8+. A possible mechanism of generation of the vertical electric fields in the mesosphere caused by gravitational sedimentation of charged aerosol particles is discussed. Simultaneous existence in the mesosphere of both the negative and positive multiply charged aerosol particles of different sizes is assumed for explanation of the observed V/m vertical electric fields and their behaviour under geomagnetically disturbed conditions.Keywords. Atmospheric composition and structure (aerosols and particles · Ionosphere (electric fields and currents · Meteorology and atmospheric dynamics (atmospheric electricity

Temperature/electric field scaling in Ferroelectrics

Energy Technology Data Exchange (ETDEWEB)

Hajjaji, Abdelowahed, E-mail: Hajjaji12@gmail.co [Laboratoire de Genie Electrique et Ferroelectricite, LGEF, INSA LYON, Bat. Gustave Ferrie, 69621 Villeurbanne Cedex (France); Guyomar, Daniel; Pruvost, Sebastien [Laboratoire de Genie Electrique et Ferroelectricite, LGEF, INSA LYON, Bat. Gustave Ferrie, 69621 Villeurbanne Cedex (France); Touhtouh, Samira [Laboratoire de Physique de la Matiere Condensee, LPMC, Departement de Physique, Faculte des Sciences, 24000 El-Jadida, Maroc (Morocco); Yuse, Kaori [Laboratoire de Genie Electrique et Ferroelectricite, LGEF, INSA LYON, Bat. Gustave Ferrie, 69621 Villeurbanne Cedex (France); Boughaleb, Yahia [Laboratoire de Physique de la Matiere Condensee, LPMC, Departement de Physique, Faculte des Sciences, 24000 El-Jadida, Maroc (Morocco)

2010-07-01

The effects of the field amplitude (E) and temperature on the polarization and their scaling relations were investigated on rhombohedral PMN-xPT ceramics. The scaling law was based on the physical symmetries of the problem and rendered it possible to express the temperature variation ({Delta}{theta}) as an electric field equivalent {Delta}E{sub eq}=({alpha}+2{beta}xP(E,{theta}{sub 0}))x{Delta}{theta}. Consequently, this was also the case for the relationship between the entropy ({Gamma}) and polarization (P). Rhombohedral Pb(Mg{sub 1/3}Nb{sub 2/3}){sub 0.75}Ti{sub 0.25}O{sub 3} ceramics were used for the verification. It was found that such an approach permitted the prediction of the maximal working temperature, using only purely electrical measurements. It indicates that the working temperature should not exceed 333 K. This value corresponds to the temperature maximum before the dramatic decrease of piezoelectric properties. Reciprocally, the polarization behavior under electrical field can be predicted, using only purely thermal measurements. The scaling law enabled a prediction of the piezoelectric properties (for example, d{sub 31}) under an electrical field replacing the temperature variation ({Delta}{theta}) by {Delta}E/({alpha}+2{beta}xp(E,{theta}{sub 0})). Inversely, predictions of the piezoelectric properties (d{sub 31}) as a function of temperature were permitted using purely only electrical measurements.

Temperature/electric field scaling in Ferroelectrics

International Nuclear Information System (INIS)

Hajjaji, Abdelowahed; Guyomar, Daniel; Pruvost, Sebastien; Touhtouh, Samira; Yuse, Kaori; Boughaleb, Yahia

2010-01-01

The effects of the field amplitude (E) and temperature on the polarization and their scaling relations were investigated on rhombohedral PMN-xPT ceramics. The scaling law was based on the physical symmetries of the problem and rendered it possible to express the temperature variation (Δθ) as an electric field equivalent ΔE eq =(α+2βxP(E,θ 0 ))xΔθ. Consequently, this was also the case for the relationship between the entropy (Γ) and polarization (P). Rhombohedral Pb(Mg 1/3 Nb 2/3 ) 0.75 Ti 0.25 O 3 ceramics were used for the verification. It was found that such an approach permitted the prediction of the maximal working temperature, using only purely electrical measurements. It indicates that the working temperature should not exceed 333 K. This value corresponds to the temperature maximum before the dramatic decrease of piezoelectric properties. Reciprocally, the polarization behavior under electrical field can be predicted, using only purely thermal measurements. The scaling law enabled a prediction of the piezoelectric properties (for example, d 31 ) under an electrical field replacing the temperature variation (Δθ) by ΔE/(α+2βxp(E,θ 0 )). Inversely, predictions of the piezoelectric properties (d 31 ) as a function of temperature were permitted using purely only electrical measurements.

Flame spread over inclined electrical wires with AC electric fields

KAUST Repository

Lim, Seung J.; Park, Sun H.; Park, Jeong; Fujita, Osamu; Keel, Sang I.; Chung, Suk-Ho

2017-01-01

Flame spread over polyethylene-insulated electrical wires was studied experimentally with applied alternating current (AC) by varying the inclination angle (θ), applied voltage (VAC), and frequency (fAC). For the baseline case with no electric field

Effect of the radial electric field on turbulence

International Nuclear Information System (INIS)

Carreras, B.A.; Lynch, V.E.

1990-01-01

For many years, the neoclassical transport theory for three- dimensional magnetic configurations, such as magnetic mirrors, ELMO Bumpy Tori (EBTs), and stellarators, has recognized the critical role of the radial electric field in the confinement. It was in these confinement devices that the first experimental measurements of the radial electric field were made and correlated with confinement losses. In tokamaks, the axisymmetry implies that the neoclassical fluxes are ambipolar and, as a consequence, independent of the radial electric field. However, axisymmetry is not strict in a tokamak with turbulent fluctuations, and near the limiter ambipolarity clearly breaks down. Therefore, the question of the effect of the radial electric field on tokamak confinement has been raised in recent years. In particular, the radial electric field has been proposed to explain the transition from L-mode to H-mode confinement. There is some initial experimental evidence supporting this type of explanation, although there is not yet a self-consistent theory explaining the generation of the electric field and its effect on the transport. Here, a brief review of recent results is presented. 27 refs., 4 figs

Electric double layer transistors with ferroelectric BaTiO3 channels

NARCIS (Netherlands)

Ito, M.; Matsubara, Y.; Kozuka, Y.; Takahashi, K. S.; Kagawa, F.; Ye, J. T.; Iwasa, Y.; Ueno, K.; Tokura, Y.; Kawasaki, M.

2014-01-01

We report the surface conduction of a BaTiO3 thin film using electric double layer transistor (EDLT) structure. A transistor operation was observed at 220 K with an on/off ratio exceeding 10(5), demonstrating that ionic liquid gating is effective to induce carriers at the surface of ferroelectric

Pulsed electric field inactivation in a microreactor

NARCIS (Netherlands)

Fox, M.B.

2006-01-01

Pulsed electric fields (PEF) is a novel, non-thermal pasteurization method which uses short, high electric field pulses to inactivate microorganisms. The advantage of a pasteurization method like PEF compared to regular heat pasteurization is that the taste, flavour, texture and nutritional value

Two devices for atmospheric electric field measurement

International Nuclear Information System (INIS)

Colombet, Andre; Hubert, Pierre.

1977-02-01

Two instruments installed at St Privat d'Allier for electric field measurement in connection with the rocket triggered lighting experiment program are described. The first one is a radioactive probe electrometer used as a warning device. The second is a field mill used for tape recording of electric field variation during the triggering events. Typical examples of such records are given [fr

Quark pair creation in color electric fields and effects of magnetic fields

International Nuclear Information System (INIS)

Tanji, Noato

2010-01-01

The time evolution of a system where a uniform and classical SU(3) color electric field and quantum fields of quarks interact with each other is studied focusing on non-perturbative pair creation and its back reaction. We characterize a color direction of an electric field in a gauge invariant way, and investigate its dependence. Momentum distributions of created quarks show plasma oscillation as well as quantum effects such as the Pauli blocking and interference. Pressure of the system is also calculated, and we show that pair creation moderates degree of anisotropy of pressure. Furthermore, enhancement of pair creation and induction of chiral charge under a color magnetic field which is parallel to an electric field are discussed.

Does electrical double layer formation lead to salt exclusion or to uptake?

NARCIS (Netherlands)

Lyklema, J.

2005-01-01

When electric double layers are formed, cases have been reported where this formation nvolves expulsion of electrolyte into the solution and cases in which electrolyte is absorbed from the solution. Both situations are experimentally and theoretically documented, but they cannot be simultaneously

Effects of geomagnetic activity on the mesospheric electric fields

Directory of Open Access Journals (Sweden)

A. M. Zadorozhny

Full Text Available The results of three series of rocket measurements of mesospheric electric fields carried out under different geomagnetic conditions at polar and high middle latitudes are analysed. The measurements show a clear dependence of the vertical electric fields on geomagnetic activity at polar and high middle latitudes. The vertical electric fields in the lower mesosphere increase with the increase of geomagnetic indexes K_p and ∑K_p. The simultaneous increase of the vertical electric field strength and ion conductivity was observed in the mesosphere during geomagnetic disturbances. This striking phenomenon was displayed most clearly during the solar proton events of October, 1989 accompanied by very strong geomagnetic storm (K_p=8+. A possible mechanism of generation of the vertical electric fields in the mesosphere caused by gravitational sedimentation of charged aerosol particles is discussed. Simultaneous existence in the mesosphere of both the negative and positive multiply charged aerosol particles of different sizes is assumed for explanation of the observed V/m vertical electric fields and their behaviour under geomagnetically disturbed conditions.

Keywords. Atmospheric composition and structure (aerosols and particles · Ionosphere (electric fields and currents · Meteorology and atmospheric dynamics (atmospheric electricity

Electric field measurements in the auroral E region

International Nuclear Information System (INIS)

Mahon, H.P.; Smiddy, M.; Sagalyn, R.C.

1975-01-01

Dipole electric field, positive ion and electron densities and temperatures, vehicle potential, and plasma sheath measurements have been made in the auroral E region by means of rockets flown from Fort Churchill, Canada. These results are described and compared over the altitude region 100 to 165 km. On a rocket flight launched on 10 December 1969 during very quiet conditions, adjacent to a stable, low intensity auroral arc, the plasma density and temperatures are found to be high and the electric fields large and steady. Electric field components of the order of -17 mv m -1 to +6 mv m -1 were measured along the Earth's magnetic field. The plasma results indicate that these fields may be contributing to enhanced electron temperatures. On a flight of 9 March 1970 during a large magnetic storm with widespread auroral activity, lower plasma densities and temperatures and much smaller and more erratic electric fields were observed with no significant component parallel to the magnetic field. (auth)

Les mécanismes d'action des détergents et les doubles couche électriques aux interfaces Action Mechanisms of Detergents and Double Electric Layer At Interfaces

Directory of Open Access Journals (Sweden)

Briant J.

2006-11-01

Full Text Available Les doubles couches électriques aux interfaces jouent un rôle important dans l'action des additifs détergents ioniques, surtout dans la stabilisation des suspensions. Les phénomènes électrocinétiques aux interfaces : électroosmose, potentiel d'écoulement, électrophorèse, potentiel de sédimentation permettent de mettre en évidence la double couche électrique et d'en déterminer certaines caractéristiques signe de la charge de la couche mobile, potentiel électrocinétique, etc. Les relations entre la stabilité des suspensions et l'interaction des doubles couches électriques ont fait l'objet d'études approfondies de Deriaguin, Verwey et Overbeek. Ces auteurs ont analysé le mécanisme d'action des doubles couches électriques et la façon dont elles pouvaient créer des forces de répulsion capables de surmonter les forces d'attraction de Van der Waals entre particules. Leur analyse permet d'expliquer les observations faites sur les effets de la charge des particules, la nature des ions fixés, la concentration de la phase dispersante en produits actifs. Le mécanisme d'action des doubles couches électriques permet peut-être d'appréhender mieux le mécanisme d'action des additifs non ioniques. Double electric loyers at interfaces play an important part in the action of ionic detergent additives, especially in the stability of suspensions. Electrokinetic phenomena at interfaces (electroosmosis,flow potential, electrophoresis, sedimentation potential can be used to reveal the double electric layer and to determine various properties such as the sign of the charge of the mobile loyer, the electrokinetic potential, etc. The relations between the stabillity of suspensions and the interaction of double electric loyers have been the subject of in-depth research by Deriaguin, Verwey and Overbeek. The authors have analyzed the action mechanism of double electric loyers and the way they can create repulsion forces capable of overcoming

Effects of an electric field on white sharks: in situ testing of an electric deterrent.

Directory of Open Access Journals (Sweden)

Charlie Huveneers

Full Text Available Elasmobranchs can detect minute electromagnetic fields, <1 nV cm(-1, using their ampullae of Lorenzini. Behavioural responses to electric fields have been investigated in various species, sometimes with the aim to develop shark deterrents to improve human safety. The present study tested the effects of the Shark Shield Freedom7™ electric deterrent on (1 the behaviour of 18 white sharks (Carcharodon carcharias near a static bait, and (2 the rates of attacks on a towed seal decoy. In the first experiment, 116 trials using a static bait were performed at the Neptune Islands, South Australia. The proportion of baits taken during static bait trials was not affected by the electric field. The electric field, however, increased the time it took them to consume the bait, the number of interactions per approach, and decreased the proportion of interactions within two metres of the field source. The effect of the electric field was not uniform across all sharks. In the second experiment, 189 tows using a seal decoy were conducted near Seal Island, South Africa. No breaches and only two surface interactions were observed during the tows when the electric field was activated, compared with 16 breaches and 27 surface interactions without the electric field. The present study suggests that the behavioural response of white sharks and the level of risk reduction resulting from the electric field is contextually specific, and depends on the motivational state of sharks.

The impact of large structural brain changes in chronic stroke patients on the electric field caused by transcranial brain stimulation

DEFF Research Database (Denmark)

Minjoli, Sena; Saturnino, Guilherme B.; Blicher, Jakob Udby

2017-01-01

aimed to characterize the impact of these changes on the spatial distribution of the electric field generated by both TBS methods. In addition to confirming the safety of TBS in the presence of large stroke-related structural changes, our aim was to clarify whether targeted stimulation is still possible....... Realistic head models containing large cortical and subcortical stroke lesions in the right parietal cortex were created using MR images of two patients. For TMS, the electric field of a double coil was simulated using the finite-element method. Systematic variations of the coil position relative...... to the lesion were tested. For TDCS, the finite-element method was used to simulate a standard approach with two electrode pads, and the position of one electrode was systematically varied. For both TMS and TDCS, the lesion caused electric field " hot spots" in the cortex. However, these maxima were...

Quantum particle in a potential well field and in an electric field

International Nuclear Information System (INIS)

Gyunter, U.; Olejnik, V.P.

1990-01-01

Solutions of the Dirac equation in the field of δ-like potential well with arbitrary symmetry and in uniform electric field were obtained and analyzed. It is shown that wave function and energy of electron in bound state in the absence of electric field depend sufficiently on the type of potential well symmetry. 1 ref

Enhanced Dielectronic Recombination in Crossed Electric and Magnetic Fields

International Nuclear Information System (INIS)

Robicheaux, F.; Pindzola, M.S.

1997-01-01

The dependence of the dielectronic recombination cross section on crossed electric and magnetic fields is described. The enhancement of this cross section due to a static electric field is further increased when a magnetic field is added perpendicular to the electric field. Calculation of this field induced enhancement is presented for a realistic atomic model, and the mechanism for the enhancement is discussed. copyright 1997 The American Physical Society

Effects of an Electric Field on White Sharks: In Situ Testing of an Electric Deterrent

Science.gov (United States)

Huveneers, Charlie; Rogers, Paul J.; Semmens, Jayson M.; Beckmann, Crystal; Kock, Alison A.; Page, Brad; Goldsworthy, Simon D.

2013-01-01

Elasmobranchs can detect minute electromagnetic fields, shark deterrents to improve human safety. The present study tested the effects of the Shark Shield Freedom7™ electric deterrent on (1) the behaviour of 18 white sharks (Carcharodon carcharias) near a static bait, and (2) the rates of attacks on a towed seal decoy. In the first experiment, 116 trials using a static bait were performed at the Neptune Islands, South Australia. The proportion of baits taken during static bait trials was not affected by the electric field. The electric field, however, increased the time it took them to consume the bait, the number of interactions per approach, and decreased the proportion of interactions within two metres of the field source. The effect of the electric field was not uniform across all sharks. In the second experiment, 189 tows using a seal decoy were conducted near Seal Island, South Africa. No breaches and only two surface interactions were observed during the tows when the electric field was activated, compared with 16 breaches and 27 surface interactions without the electric field. The present study suggests that the behavioural response of white sharks and the level of risk reduction resulting from the electric field is contextually specific, and depends on the motivational state of sharks. PMID:23658766

Density functional theory of the electrical double layer: the RFD functional

International Nuclear Information System (INIS)

Gillespie, Dirk; Valisko, Monika; Boda, Dezso

2005-01-01

Density functional theory (DFT) of electrolytes is applied to the electrical double layer under a wide range of conditions. The ions are charged, hard spheres of different size and valence, and the wall creating the double layer is uncharged, weakly charged, and strongly charged. Under all conditions, the density and electrostatic potential profiles calculated using the recently proposed RFD electrostatic functional (Gillespie et al 2002 J. Phys.: Condens. Matter 14 12129; 2003 Phys. Rev. E 68 031503) compare well to Monte Carlo simulations. When the wall is strongly charged, the RFD functional results agree with the results of a simpler perturbative electrostatic DFT, but the two functionals' results qualitatively disagree when the wall is uncharged or weakly charged. The RFD functional reproduces these phenomena of weakly charged double layers. It also reproduces bulk thermodynamic quantities calculated from pair correlation functions

Electric field effect on the emission rate of H4F and H4S hole traps in InP

International Nuclear Information System (INIS)

Darwich, R.; Alek, B.

2010-01-01

The electric field effect on the emission rate enhancement of the H4 F and H4 S hole trap in highly Zn-doped InP has been examined using the deep level transient spectroscopy (DLTS) and double correlation DLTS (DDLTS). The DLTS and DDLTS results have been found to be in good agreement for low and intermediate electric fields, but they disagree for large field effect. Comparing our emission data with the theory, we have found that H4 F obeys the quantum model of phonon-assisted tunneling while H4 S follows the Poole-Frenkel model employing a three-dimensional screening coulombic potential. Our results show that the H4 S defect can be attributed to a charged (V p - Zn) complex. (author)

Electric arc behaviour in dynamic magnetic fields

International Nuclear Information System (INIS)

Put'ko, V.F.

2000-01-01

The behaviour of an electric arc in different time-dependent (dynamic) magnetic fields was investigated. New possibilities were found for spatial and energy stabilisation of a discharge, for intensifying heat exchange, extending the electric arc and distributed control of electric arc plasma. Rotating, alternating and travelling magnetic fields were studied. It was found that under the effect of a relatively low frequency of variations of dynamic magnetic fields (f 1000 Hz) the arc stabilised at the axis of the discharge chamber, the pulsation level decreased and discharge stability increased. The borders between these two arc existence modes were formed by a certain critical field variation frequency the period of which was determined by the heat relaxation time of the discharge. (author)

Technical Note: Computation of Electric Field Strength Necessary for ...

African Journals Online (AJOL)

Obviously, electric field is established by this charge. The effects of this field on the objects lying within its vicinity depend on its intensity. In this paper, the electric field of 33kV overhead line is considered. The aim of the paper is to determine the maximum electric field strength or potential gradient, E of the 33kV overhead ...

Effect of radial electric field inhomogeneity on anomalous cross field plasma flux in Heliotron/Torsatron

International Nuclear Information System (INIS)

Yamagishi, Tomejiro; Sanuki, Heiji.

1996-01-01

Anomalous cross field plasma fluxes induced by the electric field fluctuations has been evaluated in a rotating plasma with shear flow in a helical system. The anomalous ion flux is evaluated by the contribution from ion curvature drift resonance continuum in the test particle model. The radial electric field induces the Doppler frequency shift which disappears in the frequency integrated anomalous flux. The inhomogeneity of the electric field (shear flow effect), however, induces a new force term in the flux. The curvature drift resonance also induces a new force term '/ which, however, did not make large influence in the ion flux in the CHS configuration. The shear flow term in the flux combined with the electric field in neoclassical flux reduces to a first order differential equation which governs the radial profile of the electric field. Numerical results indicate that the shear flow effect is important for the anomalous cross field flux and for determination of the radial electric field particularly in the peripheral region. (author)

Inhibition of brain tumor cell proliferation by alternating electric fields

International Nuclear Information System (INIS)

Jeong, Hyesun; Oh, Seung-ick; Hong, Sunghoi; Sung, Jiwon; Jeong, Seonghoon; Yoon, Myonggeun; Koh, Eui Kwan

2014-01-01

This study was designed to investigate the mechanism by which electric fields affect cell function, and to determine the optimal conditions for electric field inhibition of cancer cell proliferation. Low-intensity (<2 V/cm) and intermediate-frequency (100–300 kHz) alternating electric fields were applied to glioblastoma cell lines. These electric fields inhibited cell proliferation by inducing cell cycle arrest and abnormal mitosis due to the malformation of microtubules. These effects were significantly dependent on the intensity and frequency of applied electric fields

Experimental Investigation of Integrated Optical Intensive Impulse Electric Field Sensors

International Nuclear Information System (INIS)

Bao, Sun; Fu-Shen, Chen

2009-01-01

We design and fabricate an integrated optical electric field sensor with segmented electrode for intensive impulse electric field measurement. The integrated optical sensor is based on a Mach–Zehnder interferometer with segmented electrodes. The output/input character of the sensing system is analysed and measured. The maximal detectable electric field range (−75 kV/m to 245 kV/m) is obtained by analysing the results. As a result, the integrated optics electric field sensing system is suitable for transient intensive electric field measurement investigation

Inhibition of brain tumor cell proliferation by alternating electric fields

Energy Technology Data Exchange (ETDEWEB)

Jeong, Hyesun; Oh, Seung-ick; Hong, Sunghoi, E-mail: shong21@korea.ac.kr, E-mail: radioyoon@korea.ac.kr [School of Biosystem and Biomedical Science, Korea University, Seoul 136-703 (Korea, Republic of); Sung, Jiwon; Jeong, Seonghoon; Yoon, Myonggeun, E-mail: shong21@korea.ac.kr, E-mail: radioyoon@korea.ac.kr [Department of Bio-convergence Engineering, Korea University, Seoul 136-703 (Korea, Republic of); Koh, Eui Kwan [Seoul Center, Korea Basic Science Institute, Seoul 136-713 (Korea, Republic of)

2014-11-17

This study was designed to investigate the mechanism by which electric fields affect cell function, and to determine the optimal conditions for electric field inhibition of cancer cell proliferation. Low-intensity (<2 V/cm) and intermediate-frequency (100–300 kHz) alternating electric fields were applied to glioblastoma cell lines. These electric fields inhibited cell proliferation by inducing cell cycle arrest and abnormal mitosis due to the malformation of microtubules. These effects were significantly dependent on the intensity and frequency of applied electric fields.

Investigation of surface charge density on solid–liquid interfaces by modulating the electrical double layer

International Nuclear Information System (INIS)

Moon, Jong Kyun; Song, Myung Won; Pak, Hyuk Kyu

2015-01-01

A solid surface in contact with water or aqueous solution usually carries specific electric charges. These surface charges attract counter ions from the liquid side. Since the geometry of opposite charge distribution parallel to the solid–liquid interface is similar to that of a capacitor, it is called an electrical double layer capacitor (EDLC). Therefore, there is an electrical potential difference across an EDLC in equilibrium. When a liquid bridge is formed between two conducting plates, the system behaves as two serially connected EDLCs. In this work, we propose a new method for investigating the surface charge density on solid–liquid interfaces. By mechanically modulating the electrical double layers and simultaneously applying a dc bias voltage across the plates, an ac electric current can be generated. By measuring the voltage drop across a load resistor as a function of bias voltage, we can study the surface charge density on solid–liquid interfaces. Our experimental results agree very well with the simple equivalent electrical circuit model proposed here. Furthermore, using this method, one can determine the polarity of the adsorbed state on the solid surface depending on the material used. We expect this method to aid in the study of electrical phenomena on solid–liquid interfaces. (paper)

Optical Remote Sensing of Electric Fields Above Thunderstorms

Science.gov (United States)

Burns, B. M.; Carlson, B. E.; Lauben, D.; Cohen, M.; Smith, D.; Inan, U. S.

2010-12-01

Measurement of thunderstorm electric fields typically require balloon-borne measurements in the region of interest. Such measurements are cumbersome and provide limited information at a single point. Remote sensing of electric fields by Kerr-effect induced optical polarization changes of background skylight circumvents many of these difficulties and can in principle provide a high-speed movie of electric field behavior. Above-thundercloud 100 kV/m quasi-static electric fields are predicted to produce polarization changes at above the part in one million level that should be detectable at a ground instrument featuring 1 cm2sr geometric factor and 1 kHz bandwidth (though more sensitivity is nonetheless desired). Currently available optical and electronic components may meet these requirements. We review the principles of this measurement and discuss the current status of a field-ready prototype instrument currently in construction.

Research on an Axial Magnetic-Field-Modulated Brushless Double Rotor Machine

Directory of Open Access Journals (Sweden)

Bin Yu

2013-09-01

Full Text Available Double rotor machine, an electronic continuously variable transmission, has great potential in application of hybrid electric vehicles (HEVs, wind power and marine propulsion. In this paper, an axial magnetic-field-modulated brushless double rotor machine (MFM-BDRM, which can realize the speed decoupling between the shaft of the modulating ring rotor and that of the permanent magnet rotor is proposed. Without brushes and slip rings, the axial MFM-BDRM offers significant advantages such as excellent reliability and high efficiency. Since the number of pole pairs of the stator is not equal to that of the permanent magnet rotor, which differs from the traditional permanent magnet synchronous machine, the operating principle of the MFM-BDRM is deduced. The relations of corresponding speed and toque transmission are analytically discussed. The cogging toque characteristics, especially the order of the cogging torque are mathematically formulated. Matching principle of the number of pole pairs of the stator, that of the permanent magnet rotor and the number of ferromagnetic pole pieces is inferred since it affects MFM-BDRM’s performance greatly, especially in the respect of the cogging torque and electromagnetic torque ripple. The above analyses are assessed with the three-dimensional (3D finite-element method (FEM.

Visualization of induced electric fields

NARCIS (Netherlands)

Deursen, van A.P.J.

2005-01-01

A cylindrical electrolytic tank between a set of Helmholtz coils provides a classroom demonstration of induced, nonconservative electric fields. The field strength is measured by a sensor consisting of a pair of tiny spheres immersed in the liquid. The sensor signal depends on position, frequency,

Interactions between Radial Electric Field, Transport and Structure in Helical Plasmas

International Nuclear Information System (INIS)

Ida, Katsumi and others

2006-01-01

Control of the radial electric field is considered to be important in helical plasmas, because the radial electric field and its shear are expected to reduce neoclassical and anomalous transport, respectively. Particle and heat transport, that determines the radial structure of density and electron profiles, sensitive to the structure of radial electric field. On the other hand, the radial electric field itself is determined by the plasma parameters. In general, the sign of the radial electric field is determined by the plasma collisionality, while the magnitude of the radial electric field is determined by the temperature and/or density gradients. Therefore the structure of radial electric field and temperature and density are strongly coupled through the particle and heat transport and formation mechanism of radial electric field. Interactions between radial electric field, transport and structure in helical plasmas is discussed based on the experiments on Large Helical Device

Roles of electric field on toroidal magnetic confinement

International Nuclear Information System (INIS)

Itoh, Kimitaka; Itoh, Sanae; Sanuki, Heiji; Fukuyama, Atsushi.

1992-11-01

Theoretical research on the influence of the electric field on the toroidal magnetic confinement is surveyed. The static electric field is first described. Physics pictures on the generation of the radial electric field and the influence on the confinement are shown. Neoclassical effects as well as the nonclassical processes are discussed. Emphasis is made on the connection with the improved confinement. Convective cell, i.e. the nonuniform potential on the magnetic surface is also discussed. The roles of the fluctuating electric field are then reviewed. The progress in the recent theories on the anomalous transport is addressed. Through these surveys, the impact of the experiments using the heavy ion beam probes on the modern plasma physics is illustrated. (author) 66 refs

On the electric field model for an open magnetosphere

Science.gov (United States)

Wang, Zhi; Ashour-Abdalla, Maha; Walker, Raymond J.

1993-01-01

We have developed a new canonical separator line type magnetospheric magnetic field and electric field model for use in magnetospheric calculations, we determine the magnetic and electric field by controlling the reconnection rate at the subsolar magnetopause. The model is applicable only for purely southward interplanetary magnetic field (IMF). We have obtained a more realistic magnetotail configuration by applying a stretch transformation to an axially symmetric field solution. We also discuss the Stern singularity in which there is an electric field singlarity in the canonical separate line models for B(sub y) not = to 0 by using a new technique that solves for the electric field along a field line directly instead of determining it by a potential mapping. The singularity not only causes an infinite electric field on the polar cap, but also causes the boundary conditions at plus infinity and minus infinity in the solar wind to contradict each other. This means that the canonical separator line models do not represent the open magnetosphere well, except for the case of purely southward IMF.

Intense laser effects on donor impurity in a cylindrical single and vertically coupled quantum dots under combined effects of hydrostatic pressure and applied electric field

International Nuclear Information System (INIS)

Duque, C.A.; Kasapoglu, E.; Sakiroglu, S.; Sari, H.; Soekmen, I.

2010-01-01

Using the effective mass and parabolic band approximations and a variational procedure we have calculated the combined effects of intense laser radiation, hydrostatic pressure, and applied electric field on shallow-donor impurity confined in cylindrical-shaped single and double GaAs-Ga 1-x Al x As QD. Several impurity positions and inputs of the heterostructure dimensions, hydrostatic pressure, and applied electric field have been considered. The laser effects have been introduced by a perturbative scheme in which the Coulomb and the barrier potentials are modified to obtain dressed potentials. Our findings suggest that (1) for on-center impurities in single QD the binding energy is a decreasing function of the dressing parameter and for small dot dimensions of the structures (lengths and radius) the binding energy is more sensitive to the dressing parameter, (2) the binding energy is an increasing/decreasing function of the hydrostatic pressure/applied electric field, (3) the effects of the intense laser field and applied electric field on the binding energy are dominant over the hydrostatic pressure effects, (4) in vertically coupled QD the binding energy for donor impurity located in the barrier region is smaller than for impurities in the well regions and can be strongly modified by the laser radiation, and finally (5) in asymmetrical double QD heterostructures the binding energy as a function of the impurity positions follows a similar behavior to the observed for the amplitude of probability of the noncorrelated electron wave function.

Linear electric field time-of-flight ion mass spectrometer

Science.gov (United States)

Funsten, Herbert O [Los Alamos, NM; Feldman, William C [Los Alamos, NM

2008-06-10

A linear electric field ion mass spectrometer having an evacuated enclosure with means for generating a linear electric field located in the evacuated enclosure and means for injecting a sample material into the linear electric field. A source of pulsed ionizing radiation injects ionizing radiation into the linear electric field to ionize atoms or molecules of the sample material, and timing means determine the time elapsed between ionization of atoms or molecules and arrival of an ion out of the ionized atoms or molecules at a predetermined position.

Field distribution and DNA transport in solid tumors during electric field-mediated gene delivery.

Science.gov (United States)

Henshaw, Joshua W; Yuan, Fan

2008-02-01

Gene therapy has a great potential in cancer treatment. However, the efficacy of cancer gene therapy is currently limited by the lack of a safe and efficient means to deliver therapeutic genes into the nucleus of tumor cells. One method under investigation for improving local gene delivery is based on the use of pulsed electric field. Despite repeated demonstration of its effectiveness in vivo, the underlying mechanisms behind electric field-mediated gene delivery remain largely unknown. Without a thorough understanding of these mechanisms, it will be difficult to further advance the gene delivery. In this review, the electric field-mediated gene delivery in solid tumors will be examined by following individual transport processes that must occur in vivo for a successful gene transfer. The topics of examination include: (i) major barriers for gene delivery in the body, (ii) distribution of electric fields at both cell and tissue levels during the application of external fields, and (iii) electric field-induced transport of genes across each of the barriers. Through this approach, the review summarizes what is known about the mechanisms behind electric field-mediated gene delivery and what require further investigations in future studies.

Resonance double magnetic bremsstrahlung in a strong magnetic field

International Nuclear Information System (INIS)

Fomin, P.I.; Kholodov, R.I.

2003-01-01

The possibility of resonance double magnetic bremsstrahlung in the approximation of weakly excited electron states in a strong external magnetic field is analyzed. The differential probability of this process in the Breit-Wigner form is obtained. The probability of double magnetic bremsstrahlung (second-order process of perturbation theory) is compared with the probability of magnetic bremsstrahlung (first-order process of perturbation theory)

Application of electric double layer capacitor to pulse coil power supply

International Nuclear Information System (INIS)

Abe, Keita; Inomoto, Michiaki; Yamada, Takuma; Kamio, Shuji; Sakumura, Morio; Cao, Qinghong; Ono, Yasushi; Kuwahata, Akihiro; Imazawa, Ryota

2011-01-01

We developed a new application of the electric double layer capacitor (EDLC) as a sec-order quasi-DC power supply like flying-wheel motor-generators. We constructed the power supply using IGBT switching circuit and successfully demonstrated its initial operation whose current and duration time are 100 A and 3 sec, respectively, indicating a new potential of EDLC. (author)

Electrical degradation of double-Schottky barrier in ZnO varistors

Energy Technology Data Exchange (ETDEWEB)

He, Jinliang, E-mail: hejl@tsinghua.edu.cn; Cheng, Chenlu; Hu, Jun [The State Key Lab of Power System, Department of Electrical Engineering, Tsinghua University, Beijing 100084 (China)

2016-03-15

Researches on electrical degradation of double-Schottky barrier in ZnO varistors are reviewed, aimed at the constitution of a full picture of universal degradation mechanism within the perspective of defect. Recent advances in study of ZnO materials by atomic-scale first-principles calculations are partly included and discussed, which brings to our attention distinct cognition on the native point defects and their profound impact on degradation.

Electric field stimulated growth of Zn whiskers

Energy Technology Data Exchange (ETDEWEB)

Niraula, D.; McCulloch, J.; Irving, R.; Karpov, V. G. [Department of Physics and Astronomy, University of Toledo, Toledo, OH 43606 (United States); Warrell, G. R.; Shvydka, Diana, E-mail: diana.shvydka@utoledo.edu [Department of Radiation Oncology, University of Toledo Health Science Campus, Toledo, Ohio 43614 (United States)

2016-07-15

We have investigated the impact of strong (∼10{sup 4} V/cm) electric fields on the development of Zn whiskers. The original samples, with considerable whisker infestation were cut from Zn-coated steel floors and then exposed to electric fields stresses for 10-20 hours at room temperature. We used various electric field sources, from charges accumulated in samples irradiated by: (1) the electron beam of a scanning electron microscope (SEM), (2) the electron beam of a medical linear accelerator, and (3) the ion beam of a linear accelerator; we also used (4) the electric field produced by a Van der Graaf generator. In all cases, the exposed samples exhibited a considerable (tens of percent) increase in whiskers concentration compared to the control sample. The acceleration factor defined as the ratio of the measured whisker growth rate over that in zero field, was estimated to approach several hundred. The statistics of lengths of e-beam induced whiskers was found to follow the log-normal distribution known previously for metal whiskers. The observed accelerated whisker growth is attributed to electrostatic effects. These results offer promise for establishing whisker-related accelerated life testing protocols.

Electric field stimulated growth of Zn whiskers

Science.gov (United States)

Niraula, D.; McCulloch, J.; Warrell, G. R.; Irving, R.; Karpov, V. G.; Shvydka, Diana

2016-07-01

We have investigated the impact of strong (˜104 V/cm) electric fields on the development of Zn whiskers. The original samples, with considerable whisker infestation were cut from Zn-coated steel floors and then exposed to electric fields stresses for 10-20 hours at room temperature. We used various electric field sources, from charges accumulated in samples irradiated by: (1) the electron beam of a scanning electron microscope (SEM), (2) the electron beam of a medical linear accelerator, and (3) the ion beam of a linear accelerator; we also used (4) the electric field produced by a Van der Graaf generator. In all cases, the exposed samples exhibited a considerable (tens of percent) increase in whiskers concentration compared to the control sample. The acceleration factor defined as the ratio of the measured whisker growth rate over that in zero field, was estimated to approach several hundred. The statistics of lengths of e-beam induced whiskers was found to follow the log-normal distribution known previously for metal whiskers. The observed accelerated whisker growth is attributed to electrostatic effects. These results offer promise for establishing whisker-related accelerated life testing protocols.

ion in crossed gradient electric and magnetic fields

Indian Academy of Sciences (India)

Photodetachment cross-section for variousexternal fields and the laser polarization are calculated and displayed. A comparison with the photodetachment cross-section in crossed uniform electric and magnetic fields or in a single gradient electric field has been made.The agreement of our results with the above two special ...

Classical theory of electric and magnetic fields

CERN Document Server

Good, Roland H

1971-01-01

Classical Theory of Electric and Magnetic Fields is a textbook on the principles of electricity and magnetism. This book discusses mathematical techniques, calculations, with examples of physical reasoning, that are generally applied in theoretical physics. This text reviews the classical theory of electric and magnetic fields, Maxwell's Equations, Lorentz Force, and Faraday's Law of Induction. The book also focuses on electrostatics and the general methods for solving electrostatic problems concerning images, inversion, complex variable, or separation of variables. The text also explains ma

Study of the injection of plasma into a magnetic field of double curvature geometry; Etude de l'injection de plasma dans un champ magnetique a double courbure

Energy Technology Data Exchange (ETDEWEB)

Lasry, J [Commissariat a l' Energie Atomique, Fontenay-aux-Roses (France). Centre d' Etudes Nucleaires

1967-06-15

An hydrogen plasma puff is injected along the lines of a magnetic field with a double curvature geometry. The plasma is produced by a coaxial gun with an annular preionization system. It is shown theoretically that the electric drift of the plasma can be cancelled if a depolarizing current flows along the field lines towards a region of good transverse conductivity. The experiment shows that in these conditions the curvature drift of the ions of the plasma may be used as a very efficient process to purify the fast component of the plasma puff. The depolarizing electron currents are measured and the mutual cancellation of the electric fields developing into the oppositely curved region is demonstrated to be possible. The current densities agree with the values deduced of the curvature drift of the ions. (author) [French] Un plasma d'hydrogene est injecte le long des lignes de force d'un champ magnetique a double courbure. Le plasma est produit par un canon coaxial a preionisation annulaire. Il est montre theoriquement que la derive electrique du plasma peut etre annulee si un courant de depolarisation circule le long des lignes de force vers une region de conductivite transversale elevee. L'experience montre que dans ces conditions, la derive de courbure des ions peut etre utilisee comme un moyen efficace de purification de la composante rapide du plasma. Les courants electroniques de depolarisation sont mesures et l'annulation mutuelle des champs electriques se developpant dans les regions de courbures opposees est demontree. Les densites de courant sont en accord avec les valeurs deduites de la derive de courbure des ions. (auteur)

Double layers do accelerate particles in the auroral zone

International Nuclear Information System (INIS)

Borovsky, J.E.

1992-01-01

In response to a recent report [D. A. Bryant, R. Bingham, and U. de Angelis, Phys. Rev. Lett. 68, 37 (1991)] that makes the claim that electrostatic fields are weak in the auroral zone and that electrostatic fields cannot accelerate particles, it is pointed out that the evidence for electrostatic fields in the auroral zone is overwhelming and that these electrostatic fields often are accelerating electrons to produce aurora. The literature cited in the article above as evidence against double layers (strong electric fields) is reexamined and is found not to be evidence against double layers

Spiking patterns of a hippocampus model in electric fields

International Nuclear Information System (INIS)

Men Cong; Wang Jiang; Qin Ying-Mei; Wei Xi-Le; Deng Bin; Che Yan-Qiu

2011-01-01

We develop a model of CA3 neurons embedded in a resistive array to mimic the effects of electric fields from a new perspective. Effects of DC and sinusoidal electric fields on firing patterns in CA3 neurons are investigated in this study. The firing patterns can be switched from no firing pattern to burst or from burst to fast periodic firing pattern with the increase of DC electric field intensity. It is also found that the firing activities are sensitive to the frequency and amplitude of the sinusoidal electric field. Different phase-locking states and chaotic firing regions are observed in the parameter space of frequency and amplitude. These findings are qualitatively in accordance with the results of relevant experimental and numerical studies. It is implied that the external or endogenous electric field can modulate the neural code in the brain. Furthermore, it is helpful to develop control strategies based on electric fields to control neural diseases such as epilepsy. (interdisciplinary physics and related areas of science and technology)

Particle localization in a double-well potential by pseudo-supersymmetric fields

International Nuclear Information System (INIS)

Bagrov, V. G.; Samsonov, B. F.; Shamshutdinova, V. V.

2011-01-01

We study properties of a particle moving in a double-well potential in the two-level approximation placed in an additional external time-dependent field. Using previously established property (J. Phys. A 41, 244023 (2008)) that any two-level system possesses a pseudo-supersymmetry we introduce the notion of pseudo-supersymmetric field. It is shown that these fields, even if their time dependence is not periodical, may produce the effect of localization of the particle in one of the wells of the double-well potential.

The transient electric field measurement system for EAST device

Energy Technology Data Exchange (ETDEWEB)

Wang, Y., E-mail: wayong@ipp.ac.cn [Institute of Plasma Physics, Chinese Academy of Sciences, Hefei, Anhui (China); Ji, Z.S. [Institute of Plasma Physics, Chinese Academy of Sciences, Hefei, Anhui (China); Zhu, C.M. [The Experiment & Verification Center of State Grid Electric Power Research Institute (The Automation Equipment EMC Lab. of State Grid Co.), Nanjing, Jiangsu (China); Zhang, Z.C.; Ma, T.F.; Xu, Z.H. [Institute of Plasma Physics, Chinese Academy of Sciences, Hefei, Anhui (China)

2016-11-15

The electromagnetic environment around the Experimental Advanced Superconducting Tokamak (EAST) device is very complex during plasma discharge experiment. In order to fully monitor the changes of electric field around the EAST device during plasma discharge, a transient electric field measurement system based on PCI eXtensions for Instrumentation (PXI) platform has been designed. A digitizer is used for high-speed data acquisition of raw signals from electric field sensors, and a Field Programmable Gate Array (FPGA) module is used for realizing an on-the-fly fast Fourier transform (FFT) and inverse fast Fourier transform (IFFT) algorithm including a beforehand identified antenna factor (AF) to achieve finally a calibrated and filtered electric field measurement, then these signals can be displayed and easily analyzed. The raw signals from electric field sensors are transferred through optical fiber by optical isolation to reduce electromagnetic interference (EMI). The high speed data streaming technology is used for data storage. A prototype of this system has been realized to measure the transient electric field strength, with the real-time processing and continuous acquisition ability of one channel of 14-bit resolution and up to 50 MHz sampling rate, and 6 KHz FFT frequency resolution.

Effects of AC Electric Field on Small Laminar Nonpremixed Flames

KAUST Repository

Xiong, Yuan

2015-04-01

Electric field can be a viable method in controlling various combustion properties. Comparing to traditional actuators, an application of electric field requires very small power consumption. Especially, alternating current (AC) has received attention recently, since it could modulate flames appreciably even for the cases when direct current (DC) has minimal effects. In this study, the effect of AC electric fields on small coflow diffusion flames is focused with applications of various laser diagnostic techniques. Flow characteristics of baseline diffusion flames, which corresponds to stationary small coflow diffusion flames when electric field is not applied, were firstly investigated with a particular focus on the flow field in near-nozzle region with the buoyancy force exerted on fuels due to density differences among fuel, ambient air, and burnt gas. The result showed that the buoyancy force exerted on the fuel as well as on burnt gas significantly distorted the near-nozzle flow-fields. In the fuels with densities heavier than air, recirculation zones were formed very close to the nozzle exit. Nozzle heating effect influenced this near-nozzle flow-field particularly among lighter fuels. Numerical simulations were also conducted and the results showed that a fuel inlet boundary condition with a fully developed velocity profile for cases with long fuel tubes should be specified inside the fuel tube to obtain satisfactory agreement in both the flow and temperature fields with those from experiment. With sub-critical AC applied to the baseline flames, particle image velocimetry (PIV), light scattering, laser-induced incandescence (LII), and laser-induced fluores- cence (LIF) techniques were adopted to identify the flow field and the structures of OH, polycyclic aromatic hydrocarbons (PAHs), soot zone. Under certain AC condi- tions of applied voltage and frequency, the distribution of PAHs and the flow field near the nozzle exit were drastically altered from the

Optimized design of micromachined electric field mills to maximize electrostatic field sensitivity

OpenAIRE

Zhou, Yu; Shafai, Cyrus

2016-01-01

This paper describes the design optimization of a micromachined electric field mill, in relation to maximizing its output signal. The cases studied are for a perforated electrically grounded shutter vibrating laterally over sensing electrodes. It is shown that when modeling the output signal of the sensor, the differential charge on the sense electrodes when exposed to vs. visibly shielded from the incident electric field must be considered. Parametric studies of device dimensions show that t...

Electric field measurements in a nanosecond pulse discharge in atmospheric air

International Nuclear Information System (INIS)

Simeni Simeni, Marien; Frederickson, Kraig; Lempert, Walter R; Adamovich, Igor V; Goldberg, Benjamin M; Zhang, Cheng

2017-01-01

The paper presents the results of temporally and spatially resolved electric field measurements in a nanosecond pulse discharge in atmospheric air, sustained between a razor edge high-voltage electrode and a plane grounded electrode covered by a thin dielectric plate. The electric field is measured by picosecond four-wave mixing in a collinear phase-matching geometry, with time resolution of approximately 2 ns, using an absolute calibration provided by measurements of a known electrostatic electric field. The results demonstrate electric field offset on the discharge center plane before the discharge pulse due to surface charge accumulation on the dielectric from the weaker, opposite polarity pre-pulse. During the discharge pulse, the electric field follows the applied voltage until ‘forward’ breakdown occurs, after which the field in the plasma is significantly reduced due to charge separation. When the applied voltage is reduced, the field in the plasma reverses direction and increases again, until the weak ‘reverse’ breakdown occurs, producing a secondary transient reduction in the electric field. After the pulse, the field is gradually reduced on a microsecond time scale, likely due to residual surface charge neutralization by transport of opposite polarity charges from the plasma. Spatially resolved electric field measurements show that the discharge develops as a surface ionization wave. Significant surface charge accumulation on the dielectric surface is detected near the end of the discharge pulse. Spatially resolved measurements of electric field vector components demonstrate that the vertical electric field in the surface ionization wave peaks ahead of the horizontal electric field. Behind the wave, the vertical field remains low, near the detection limit, while the horizontal field is gradually reduced to near the detection limit at the discharge center plane. These results are consistent with time-resolved measurements of electric field

Longitudinal and transverse electric field measurements in resonant cavities

International Nuclear Information System (INIS)

Tong Dechun; Chen Linfeng; Zheng Xiaoyue

1994-01-01

The paper presents a measuring technique for the electric field distribution of high order modes in resonant cavities. A perturbing bead-like cage made with metallic wires are developed for S-band field measurements, which can be used to detect a small electric field component in the presence of other strong electric or magnetic field components (That means high sensitivity and high directivity). In order to avoid orientation error for the cage with very high directivity, two parallel threads were used for supporting the perturbing cage. A simple mechanical set-up is described. The cage can be driven into the cavity on-axis or off-axis in any azimuth for the longitudinal and transverse electric field measurements

Galvanotactic behavior of Tetrahymena pyriformis under electric fields

International Nuclear Information System (INIS)

Kim, Dal Hyung; Kim, Paul Seung Soo; Kim, Min Jun; Lee, Kyoungwoo; Kim, JinSeok

2013-01-01

Tetrahymena pyriformis, a eukaryotic ciliate, swims toward a cathode in straight or cross-shaped microchannels under an applied electric field, a behavioral response called cathodal galvanotaxis. In straight channel experiments, a one-dimensional electric field was applied, and the galvanotactic swimming behavior of Tetrahymena pyriformis was observed and described in detail while the polarity of this field is switched. In most individual cases, the cell would immediately switch its direction toward the cathode; however, exceptional cases have been observed where cells exhibit a turning delay or do not turn after a polarity switch. In cross-channel experiments, feedback control using vision-based tracking was used to steer a cell in the microchannel intersection using a two-dimensional electric field generated by four electrodes placed at four ends of the cross channel. The motivation for this work is to study the swimming behavior of Tetrahymena pyriformis as a microrobot under the control of electric fields. (paper)

Effect of increased ionization on the atmospheric electric field

International Nuclear Information System (INIS)

Boeck, W.L.

1980-01-01

This study is a review of atmospheric electrical theory with the purpose of predicting the atmospheric electrical effects of increased ionization caused by radioactive inert gases. A time-independent perturbation model for the global atmospheric electric circuit precdicts that the electric field at the sea surface would be reduced to about 76% of its unperturbed value by a surface 85 Kr concentration of 3 nCi/m 3 . The electric field at a typical land station is predicted to be about 84% of its unperturbed value. Some scientists have suggested that the atmospheric electric field is part of a closed electrical feedback loop. The present model does not include such a closed feedback loop and may underestimate the total effects. This model is also useful for interpreting atmospheric electrical responses to natural fluctuations in the cosmic-ray component of background radiation

Manipulation of red blood cells with electric field

Science.gov (United States)

Saboonchi, Hossain; Esmaeeli, Asghar

2009-11-01

Manipulation of bioparticles and macromolecules is the central task in many biological and biotechnological processes. The current methods for physical manipulation takes advantage of different forces such as acoustic, centrifugal, magnetic, electromagnetic, and electric forces, as well as using optical tweezers or filtration. Among all these methods, however, the electrical forces are particularly attractive because of their favorable scale up with the system size which makes them well-suited for miniaturization. Currently the electric field is used for transportation, poration, fusion, rotation, and separation of biological cells. The aim of the current research is to gain fundamental understanding of the effect of electric field on the human red blood cells (RBCs) using direct numerical simulation. A front tracking/finite difference technique is used to solve the fluid flow and electric field equations, where the fluid in the cell and the blood (plasma) is modeled as Newtonian and incompressible, and the interface separating the two is treated as an elastic membrane. The behavior of RBCs is investigated as a function of the controlling parameters of the problem such as the strength of the electric field.

Effects of an electric field on interaction of aromatic systems.

Science.gov (United States)

Youn, Il Seung; Cho, Woo Jong; Kim, Kwang S

2016-04-30

The effect of uniform external electric field on the interactions between small aromatic compounds and an argon atom is investigated using post-HF (MP2, SCS-MP2, and CCSD(T)) and density functional (PBE0-D3, PBE0-TS, and vdW-DF2) methods. The electric field effect is quantified by the difference of interaction energy calculated in the presence and absence of the electric field. All the post-HF methods describe electric field effects accurately although the interaction energy itself is overestimated by MP2. The electric field effect is explained by classical electrostatic models, where the permanent dipole moment from mutual polarization mainly determines its sign. The size of π-conjugated system does not have significant effect on the electric field dependence. We found out that PBE0-based methods give reasonable interaction energies and electric field response in every case, while vdW-DF2 sometimes shows spurious artifact owing to its sensitivity toward the real space electron density. © 2015 Wiley Periodicals, Inc.

Theoretical study of structure of electric field in helical toroidal plasmas

International Nuclear Information System (INIS)

Toda, S.; Itoh, K.

2001-06-01

A set of transport equations is analyzed, including the bifurcation of the electric field. The structure of the electric field is studied by use of the theoretical model for the anomalous transport diffusivities. The steep gradient of the electric field is obtained at the electric domain. The suppression of the anomalous transport diffusivity is studied in the presence of the strong shear of the electric field. The hard transition with the multiple ambipolar solutions is examined in the structure of the radial electric field. The details of the structure of the electric domain interface are investigated. (author)

Vector optical fields with polarization distributions similar to electric and magnetic field lines.

Science.gov (United States)

Pan, Yue; Li, Si-Min; Mao, Lei; Kong, Ling-Jun; Li, Yongnan; Tu, Chenghou; Wang, Pei; Wang, Hui-Tian

2013-07-01

We present, design and generate a new kind of vector optical fields with linear polarization distributions modeling to electric and magnetic field lines. The geometric configurations of "electric charges" and "magnetic charges" can engineer the spatial structure and symmetry of polarizations of vector optical field, providing additional degrees of freedom assisting in controlling the field symmetry at the focus and allowing engineering of the field distribution at the focus to the specific applications.

Dynamics analysis of extraction of manganese intensified by electric field

Science.gov (United States)

Ma, Wenrui; Tao, Changyuan; Li, Huizhan; Liu, Zuohua; Liu, Renlong

2018-06-01

In this study, a process reinforcement technology for leaching process of pyrolusite was developed. The electric field was introduced to decrease reaction temperature and improve the leaching rate of pyrolusite. The mechanisms of electric field intensifying leaching process of pyrolusite were investigated through X-ray diffraction (XRD), and Brunauer Emmett Teller (BET) in detail. The results showed that the electric field could decrease obviously the apparent activation energy of leaching process of pyrolusite. The apparent activation energy of the leaching of pyrolusite intensified by electric field was calculated to be 53.76 kJ.mol-1. In addition, the leaching efficiency of manganese was effectively increased by 10% to 20% than that without electric field under the same conditions. This was because that the electron conduit between Fe (II)/Fe (III) and pyrite was dredged effectively by electric field.

A Model for Periodic Nonlinear Electric Field Structures in Space Plasmas

International Nuclear Information System (INIS)

Qureshi, M.N.S.; Shi Jiankui; Liu Zhenxing

2009-01-01

In this study, we present a physical model to explain the generation mechanism of nonlinear periodic waves with a large amplitude electric field structures propagating obliquely and exactly parallel to the magnetic field. The 'Sagdeev potential' from the MHD equations is derived and the nonlinear electric field waveforms are obtained when the Mach number, direction of propagation, and the initial electric field satisfy certain plasma conditions. For the parallel propagation, the amplitude of the electric field waves with ion-acoustic mode increases with the increase of initial electric field and Mach number but its frequency decreases with the increase of Mach number. The amplitude and frequency of the electric field waves with ion-cyclotron mode decrease with the increase of Mach number and become less spiky, and its amplitude increases with the increase of initial electric field. For the oblique propagation, only periodic electric field wave with an ion-cyclotron mode obtained, its amplitude and frequency increase with the increase of Mach number and become spiky. From our model the electric field structures show periodic, spiky, and saw-tooth behaviours corresponding to different plasma conditions.

Electric-field-modified Feshbach resonances in ultracold atom–molecule collision

International Nuclear Information System (INIS)

Cheng Dong; Li Ya; Feng Eryin; Huang Wuying

2017-01-01

We present a detailed analysis of near zero-energy Feshbach resonances in ultracold collisions of atom and molecule, taking the He–PH system as an example, subject to superimposed electric and magnetic static fields. We find that the electric field can induce Feshbach resonance which cannot occur when only a magnetic field is applied, through couplings of the adjacent rotational states of different parities. We show that the electric field can shift the position of the magnetic Feshbach resonance, and change the amplitude of resonance significantly. Finally, we demonstrate that, for narrow magnetic Feshbach resonance as in most cases of ultracold atom–molecule collision, the electric field may be used to modulate the resonance, because the width of resonance in electric field scale is relatively larger than that in magnetic field scale. (paper)

A mini review of designed mesoporous materials for energy-storage applications: from electric double-layer capacitors to hybrid supercapacitors

Science.gov (United States)

Lim, Eunho; Jo, Changshin; Lee, Jinwoo

2016-04-01

In recent years, porous materials have attracted significant attention in various research fields because of their structural merits. In particular, well-designed mesoporous structures with two- or three-dimensionally interconnected pores have been recognized as electrode materials of particular interest for achieving high-performance electrochemical capacitors (ECs). In this mini review, recent progress in the design of mesoporous electrode materials for ECs, from electric double-layer capacitors (EDLCs) and pseudocapacitors (PCs) to hybrid supercapacitors (HSCs), and research challenges for the development of new mesoporous electrode materials has been discussed.

Modeling Electric Double-Layers Including Chemical Reaction Effects

DEFF Research Database (Denmark)

Paz-Garcia, Juan Manuel; Johannesson, Björn; Ottosen, Lisbeth M.

2014-01-01

A physicochemical and numerical model for the transient formation of an electric double-layer between an electrolyte and a chemically-active flat surface is presented, based on a finite elements integration of the nonlinear Nernst-Planck-Poisson model including chemical reactions. The model works...... for symmetric and asymmetric multi-species electrolytes and is not limited to a range of surface potentials. Numerical simulations are presented, for the case of a CaCO3 electrolyte solution in contact with a surface with rate-controlled protonation/deprotonation reactions. The surface charge and potential...... are determined by the surface reactions, and therefore they depends on the bulk solution composition and concentration...

Electric Double-Layer Capacitor Fabricated with Addition of Carbon Nanotube to Polarizable Electrode

OpenAIRE

Yoshiyuki Show

2012-01-01

Electrical double-layer capacitor (EDLC) was fabricated with addition of carbon nanotube (CNT) to polarization electrodes as a conducting material. The CNT addition reduced the series resistance of the EDLC by one-twentieth, while the capacitance was not increased by the CNT addition. The low series resistance leaded to the high electrical energy stored in the EDLC. In this paper, the dependence of the series resistance, the specific capacitance, the energy, and the energy efficiencies on the...

Molecules with an induced dipole moment in a stochastic electric field.

Science.gov (United States)

Band, Y B; Ben-Shimol, Y

2013-10-01

The mean-field dynamics of a molecule with an induced dipole moment (e.g., a homonuclear diatomic molecule) in a deterministic and a stochastic (fluctuating) electric field is solved to obtain the decoherence properties of the system. The average (over fluctuations) electric dipole moment and average angular momentum as a function of time for a Gaussian white noise electric field are determined via perturbative and nonperturbative solutions in the fluctuating field. In the perturbative solution, the components of the average electric dipole moment and the average angular momentum along the deterministic electric field direction do not decay to zero, despite fluctuations in all three components of the electric field. This is in contrast to the decay of the average over fluctuations of a magnetic moment in a Gaussian white noise magnetic field. In the nonperturbative solution, the component of the average electric dipole moment and the average angular momentum in the deterministic electric field direction also decay to zero.

MgB2 superconducting particles in a strong electric field

International Nuclear Information System (INIS)

Tao, R.; Xu, X.; Amr, E.

2003-01-01

The electric-field induced ball formation has been observed with MgB 2 powder in a strong static or quasi-static electric field. The effect of temperature and magnetic field on the ball formation shows surprising features. For quite a wide range of temperature from T c =39 K and below, the ball size is proportional to (1-T/T c ). As the temperature further goes below 20 K, the ball size becomes almost a constant. If MgB 2 particles are in a strong electric field and a moderate magnetic field, the electric-field induced balls align in the magnetic-field direction to form ball chains

Surface electric fields for North America during historical geomagnetic storms

Science.gov (United States)

Wei, Lisa H.; Homeier, Nichole; Gannon, Jennifer L.

2013-01-01

To better understand the impact of geomagnetic disturbances on the electric grid, we recreate surface electric fields from two historical geomagnetic storms—the 1989 “Quebec” storm and the 2003 “Halloween” storms. Using the Spherical Elementary Current Systems method, we interpolate sparsely distributed magnetometer data across North America. We find good agreement between the measured and interpolated data, with larger RMS deviations at higher latitudes corresponding to larger magnetic field variations. The interpolated magnetic field data are combined with surface impedances for 25 unique physiographic regions from the United States Geological Survey and literature to estimate the horizontal, orthogonal surface electric fields in 1 min time steps. The induced horizontal electric field strongly depends on the local surface impedance, resulting in surprisingly strong electric field amplitudes along the Atlantic and Gulf Coast. The relative peak electric field amplitude of each physiographic region, normalized to the value in the Interior Plains region, varies by a factor of 2 for different input magnetic field time series. The order of peak electric field amplitudes (largest to smallest), however, does not depend much on the input. These results suggest that regions at lower magnetic latitudes with high ground resistivities are also at risk from the effect of geomagnetically induced currents. The historical electric field time series are useful for estimating the flow of the induced currents through long transmission lines to study power flow and grid stability during geomagnetic disturbances.

Optimized design of micromachined electric field mills to maximize electrostatic field sensitivity

Directory of Open Access Journals (Sweden)

Yu Zhou

2016-07-01

Full Text Available This paper describes the design optimization of a micromachined electric field mill, in relation to maximizing its output signal. The cases studied are for a perforated electrically grounded shutter vibrating laterally over sensing electrodes. It is shown that when modeling the output signal of the sensor, the differential charge on the sense electrodes when exposed to vs. visibly shielded from the incident electric field must be considered. Parametric studies of device dimensions show that the shutter thickness and its spacing from the underlying electrodes should be minimized as these parameters very strongly affect the MEFM signal. Exploration of the shutter perforation size and sense electrode width indicate that the best MEFM design is one where shutter perforation widths are a few times larger than the sense electrode widths. Keywords: MEFM, Finite element method, Electric field measurement, MEMS, Micromachining

Electric Potential and Electric Field Imaging with Dynamic Applications: 2017 Research Award Innovation

Science.gov (United States)

Generazio, Ed

2017-01-01

The technology and methods for remote quantitative imaging of electrostatic potentials and electrostatic fields in and around objects and in free space is presented. Electric field imaging (EFI) technology may be applied to characterize intrinsic or existing electric potentials and electric fields, or an externally generated electrostatic field may be used for illuminating volumes to be inspected with EFI. The baseline sensor technology (e-Sensor) and its construction, optional electric field generation (quasi-static generator), and current e- Sensor enhancements (ephemeral e-Sensor) are discussed. Critical design elements of current linear and real-time two-dimensional (2D) measurement systems are highlighted, and the development of a three dimensional (3D) EFI system is presented. Demonstrations for structural, electronic, human, and memory applications are shown. Recent work demonstrates that phonons may be used to create and annihilate electric dipoles within structures. Phonon induced dipoles are ephemeral and their polarization, strength, and location may be quantitatively characterized by EFI providing a new subsurface Phonon-EFI imaging technology. Initial results from real-time imaging of combustion and ion flow, and their measurement complications, will be discussed. These new EFI capabilities are demonstrated to characterize electric charge distribution creating a new field of study embracing areas of interest including electrostatic discharge (ESD) mitigation, crime scene forensics, design and materials selection for advanced sensors, combustion science, on-orbit space potential, container inspection, remote characterization of electronic circuits and level of activation, dielectric morphology of structures, tether integrity, organic molecular memory, atmospheric science, and medical diagnostic and treatment efficacy applications such as cardiac polarization wave propagation and electromyography imaging.

Limiting electric fields of HVDC overhead power lines.

Science.gov (United States)

Leitgeb, N

2014-05-01

As a consequence of the increased use of renewable energy and the now long distances between energy generation and consumption, in Europe, electric power transfer by high-voltage (HV) direct current (DC) overhead power lines gains increasing importance. Thousands of kilometers of them are going to be built within the next years. However, existing guidelines and regulations do not yet contain recommendations to limit static electric fields, which are one of the most important criteria for HVDC overhead power lines in terms of tower design, span width and ground clearance. Based on theoretical and experimental data, in this article, static electric fields associated with adverse health effects are analysed and various criteria are derived for limiting static electric field strengths.

Ionization and recombination in attosecond electric field pulses

International Nuclear Information System (INIS)

Dimitrovski, Darko; Solov'ev, Eugene A.; Briggs, John S.

2005-01-01

Based on the results of a previous communication [Dimitrovski et al., Phys. Rev. Lett. 93, 083003 (2004)], we study ionization and excitation of a hydrogenic atom from the ground and first excited states in short electric field pulses of several cycles. A process of ionization and recombination which occurs periodically in time is identified, for both small and extremely large peak electric field strengths. In the limit of large electric peak fields closed-form analytic expressions for the population of the initial state after single- and few-cycle pulses are derived. These formulas, strictly valid for asymptotically large momentum transfer from the field, give excellent agreement with fully numerical calculations for all momentum transfers

Application of a Gradient Descent Continuous Actor-Critic Algorithm for Double-Side Day-Ahead Electricity Market Modeling

Directory of Open Access Journals (Sweden)

Huiru Zhao

2016-09-01

Full Text Available An important goal of China’s electric power system reform is to create a double-side day-ahead wholesale electricity market in the future, where the suppliers (represented by GenCOs and demanders (represented by DisCOs compete simultaneously with each other in one market. Therefore, modeling and simulating the dynamic bidding process and the equilibrium in the double-side day-ahead electricity market scientifically is not only important to some developed countries, but also to China to provide a bidding decision-making tool to help GenCOs and DisCOs obtain more profits in market competition. Meanwhile, it can also provide an economic analysis tool to help government officials design the proper market mechanisms and policies. The traditional dynamic game model and table-based reinforcement learning algorithm have already been employed in the day-ahead electricity market modeling. However, those models are based on some assumptions, such as taking the probability distribution function of market clearing price (MCP and each rival’s bidding strategy as common knowledge (in dynamic game market models, and assuming the discrete state and action sets of every agent (in table-based reinforcement learning market models, which are no longer applicable in a realistic situation. In this paper, a modified reinforcement learning method, called gradient descent continuous Actor-Critic (GDCAC algorithm was employed in the double-side day-ahead electricity market modeling and simulation. This algorithm can not only get rid of the abovementioned unrealistic assumptions, but also cope with the Markov decision-making process with continuous state and action sets just like the real electricity market. Meanwhile, the time complexity of our proposed model is only O(n. The simulation result of employing the proposed model in the double-side day-ahead electricity market shows the superiority of our approach in terms of participant’s profit or social welfare

A percolation approach to study the high electric field effect on electrical conductivity of insulating polymer

Science.gov (United States)

Benallou, Amina; Hadri, Baghdad; Martinez-Vega, Juan; El Islam Boukortt, Nour

2018-04-01

The effect of percolation threshold on the behaviour of electrical conductivity at high electric field of insulating polymers has been briefly investigated in literature. Sometimes the dead ends links are not taken into account in the study of the electric field effect on the electrical properties. In this work, we present a theoretical framework and Monte Carlo simulation of the behaviour of the electric conductivity at high electric field based on the percolation theory using the traps energies levels which are distributed according to distribution law (uniform, Gaussian, and power-law). When a solid insulating material is subjected to a high electric field, and during trapping mechanism the dead ends of traps affect with decreasing the electric conductivity according to the traps energies levels, the correlation length of the clusters, the length of the dead ends, and the concentration of the accessible positions for the electrons. A reasonably good agreement is obtained between simulation results and the theoretical framework.

Superparamagnetic magnetite nanocrystals-graphene oxide nanocomposites: facile synthesis and their enhanced electric double-layer capacitor performance.

Science.gov (United States)

Wang, Qihua; Wang, Dewei; Li, Yuqi; Wang, Tingmei

2012-06-01

Superparamagnetic magnetite nanocrystals-graphene oxide (FGO) nanocomposites were successfully synthesized through a simple yet versatile one-step solution-processed approach at ambient conditions. Magnetite (Fe3O4) nanocrystals (NCs) with a size of 10-50 nm were uniformly deposited on the surfaces of graphene oxide (GO) sheets, which were confirmed by transmission electron microscopy (TEM) and high-angle annular dark field scanning transmission election microscopy (HAADF-STEM) studies. FGO with different Fe3O4 loadings could be controlled by simply manipulating the initial weight ratio of the precursors. The M-H measurements suggested that the as-prepared FGO nanocomposites have a large saturation magnetizations that made them can move regularly under an external magnetic field. Significantly, FGO nanocomposites also exhibit enhanced electric double-layer capacitor (EDLC) activity compared with pure Fe3O4 NCs and GO in terms of specific capacitance and high-rate charge-discharge.

Unified analytical treatment of multicentre electron attraction, electric field and electric field gradient integrals over Slater orbitals

International Nuclear Information System (INIS)

Guseinov, I I

2004-01-01

The new central and noncentral potential functions (CPFs and NCPFs) of a molecule depending on the coordinates of the nuclei are introduced. Using complete orthonormal sets of Ψ α -exponential-type orbitals (Ψ α -ETOs) introduced by the author, the series expansion formulae for the multicentre electronic attraction (EA), electric field (EF) and electric field gradient (EFG) integrals over Slater-type orbitals (STOs) in terms of CPFs and NCPFs are derived. The relationships obtained are valid for the arbitrary location, quantum numbers and screening constants of STOs

Novel electric double-layer capacitor with a coaxial fiber structure.

Science.gov (United States)

Chen, Xuli; Qiu, Longbin; Ren, Jing; Guan, Guozhen; Lin, Huijuan; Zhang, Zhitao; Chen, Peining; Wang, Yonggang; Peng, Huisheng

2013-11-26

A coaxial electric double-layer capacitor fiber is developed from the aligned carbon nanotube fiber and sheet, which functions as two electrodes with a polymer gel sandwiched between them. The unique coaxial structure enables a rapid transportation of ions between the two electrodes with a high electrochemical performance. These energy storage fibers are also flexible and stretchable, and can be woven into and widely used for electronic textiles. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Azimuthal electric fields and ambipolarity in a multiple-helicity torsatron

International Nuclear Information System (INIS)

Hastings, D.E.; Shaing, K.C.

1985-01-01

In a torsatron there are multiple solutions to the ambipolarity relationship for the electric field. If the electric field is small over some region of space then the self-consistent poloidal electric field can be important and lead to potential islands. If the plasma is in the superbanana plateau regime, then slow resonant particles limit the rate of change of the electric field and, hence, give a minimum width for the spatial zone where the plasma is changing roots of the ambipolarity relationship

The effect of the electrical double layer on hydrodynamic lubrication: a non-monotonic trend with increasing zeta potential

Directory of Open Access Journals (Sweden)

Dalei Jing

2017-07-01

Full Text Available In the present study, a modified Reynolds equation including the electrical double layer (EDL-induced electroviscous effect of lubricant is established to investigate the effect of the EDL on the hydrodynamic lubrication of a 1D slider bearing. The theoretical model is based on the nonlinear Poisson–Boltzmann equation without the use of the Debye–Hückel approximation. Furthermore, the variation in the bulk electrical conductivity of the lubricant under the influence of the EDL is also considered during the theoretical analysis of hydrodynamic lubrication. The results show that the EDL can increase the hydrodynamic load capacity of the lubricant in a 1D slider bearing. More importantly, the hydrodynamic load capacity of the lubricant under the influence of the EDL shows a non-monotonic trend, changing from enhancement to attenuation with a gradual increase in the absolute value of the zeta potential. This non-monotonic hydrodynamic lubrication is dependent on the non-monotonic electroviscous effect of the lubricant generated by the EDL, which is dominated by the non-monotonic electrical field strength and non-monotonic electrical body force on the lubricant. The subject of the paper is the theoretical modeling and the corresponding analysis.

Sparse Reconstruction of Electric Fields from Radial Magnetic Data

International Nuclear Information System (INIS)

Yeates, Anthony R.

2017-01-01

Accurate estimates of the horizontal electric field on the Sun’s visible surface are important not only for estimating the Poynting flux of magnetic energy into the corona but also for driving time-dependent magnetohydrodynamic models of the corona. In this paper, a method is developed for estimating the horizontal electric field from a sequence of radial-component magnetic field maps. This problem of inverting Faraday’s law has no unique solution. Unfortunately, the simplest solution (a divergence-free electric field) is not realistically localized in regions of nonzero magnetic field, as would be expected from Ohm’s law. Our new method generates instead a localized solution, using a basis pursuit algorithm to find a sparse solution for the electric field. The method is shown to perform well on test cases where the input magnetic maps are flux balanced in both Cartesian and spherical geometries. However, we show that if the input maps have a significant imbalance of flux—usually arising from data assimilation—then it is not possible to find a localized, realistic, electric field solution. This is the main obstacle to driving coronal models from time sequences of solar surface magnetic maps.

Sparse Reconstruction of Electric Fields from Radial Magnetic Data

Energy Technology Data Exchange (ETDEWEB)

Yeates, Anthony R. [Department of Mathematical Sciences, Durham University, Durham, DH1 3LE (United Kingdom)

2017-02-10

Accurate estimates of the horizontal electric field on the Sun’s visible surface are important not only for estimating the Poynting flux of magnetic energy into the corona but also for driving time-dependent magnetohydrodynamic models of the corona. In this paper, a method is developed for estimating the horizontal electric field from a sequence of radial-component magnetic field maps. This problem of inverting Faraday’s law has no unique solution. Unfortunately, the simplest solution (a divergence-free electric field) is not realistically localized in regions of nonzero magnetic field, as would be expected from Ohm’s law. Our new method generates instead a localized solution, using a basis pursuit algorithm to find a sparse solution for the electric field. The method is shown to perform well on test cases where the input magnetic maps are flux balanced in both Cartesian and spherical geometries. However, we show that if the input maps have a significant imbalance of flux—usually arising from data assimilation—then it is not possible to find a localized, realistic, electric field solution. This is the main obstacle to driving coronal models from time sequences of solar surface magnetic maps.

Electric fields and field-aligned current generation in the magnetosphere

International Nuclear Information System (INIS)

Alexeev, I.I.; Belenkaya, E.S.; Kalegaev, V.V.; Lyutov, Yu.G.

1993-01-01

The authors present a calculation of the electric potential, field-aligned currents, and plasma convection caused by the penetration of the solar wind electric field into the magnetosphere. Ohm's law and the continuity equation of ionospheric currents are used. It is shown that the large-scale convection system is reversed in the plasma sheet flanks. In this region the plasma flow is antisunward earthward of the neutral line and sunward tailward of it. The interplanetary magnetic field (IMF) B z dependences on the dimension of the magnetopause open-quotes windowsclose quotes which are intersected by open field lines, on the potential drop across the polar cap, and on the distance to the neutral line are determined. Because of the IMF effect and the effect of seasonal or daily variations of the geomagnetic field which violate its symmetry relative to the equatorial plane, there may arise a potential drop along field lines which causes field-aligned currents. The values and directions of these currents, the field-aligned potential drop, and a self-consistent solution for the potential at the ionosphere level for high field-aligned conductivity have been determined. 41 refs., 7 figs

Twice electric field poling for engineering multiperiodic Hex-PPLN microstructures

Science.gov (United States)

Pagliarulo, Vito; Gennari, Oriella; Rega, Romina; Mecozzi, Laura; Grilli, Simonetta; Ferraro, Pietro

2018-05-01

Satellite bulk ferroelectric domains were observed everywhere around the larger main inverted ferroelectric domains when a Twice Electric Field Poling (TEFP) process is applied on a z-cut lithium niobate substrate. TEFP approach can be very advantageous for engineering multiperiodic poled microstructures in ferroelectrics. In fact, it is very difficult in the experimental practice to avoid underpoling and/or overpoling when structures with different sizes are requested in the same crystal. TEFP was applied to photoresist patterned crystal with 100 μm period and then a second EP step, with a ten-times smaller periodicity of 10 μm, was accomplished on the same sample. The intriguing fact is that the shorter 10 μm pattern disappeared everywhere except that around the larger satellite ferroelectric domains. The formation of this double-periodicity in the reversed ferroelectric domains occurs very easily and in repeatedly way. We have experimentally investigated the formation of such HePPLN structures by an interference microscopy in digital holography (DH) modality. The reported results demonstrate the possibility of fabricating multi-periodic structures and open the way to investigate the possibility to achieve hierarchical PPLN structures by multiple subsequent electric poling processes.

Electric field induced dewetting at polymer/polymer interfaces

NARCIS (Netherlands)

Lin, Z.Q.; Kerle, T.; Russell, T.P.; Schäffer, E.; Steiner, U

2002-01-01

External electric fields were used to amplify interfacial fluctuations in the air/polymer/polymer system where one polymer dewets the other. Two different hydrodynamic regimes were found as a function of electric field strength. If heterogeneous nucleation leads to the formation of holes before the

Nanographene derived from carbon nanofiber and its application to electric double-layer capacitors

International Nuclear Information System (INIS)

Mitani, Satoshi; Sathish, Marappan; Rangappa, Dinesh; Unemoto, Atsushi; Tomai, Takaaki; Honma, Itaru

2012-01-01

The fascinating properties of graphene are attracting considerable attention in engineering fields such as electronics, optics, and energy engineering. These properties can be controlled by controlling graphene's structure, e.g., the number of layers and the sheet size. In this study, we synthesized nanosized graphene from a platelet-type carbon nanofiber. The thickness and size of nanographene oxide are around 1 nm and 60 nm and we obtained nanographene by hydrazine reduction of nanographene oxide. We applied the nanographene to an ionic-liquid electric double-layer capacitor (EDLC), which exhibited a much larger capacitance per specific surface area than an EDLC using conventional activated carbon. Furthermore, the capacitance increased significantly with increasing cycle time. After 30th cycle, the capacitance was achieved 130 F g −1 , though the surface area was only 240 m 2 g −1 . These results suggest that nanographene structure induce the capacitance enhancement.

[Mechanism of ablation with nanosecond pulsed electric field].

Science.gov (United States)

Cen, Chao; Chen, Xin-hua; Zheng, Shu-sen

2015-11-01

Nanosecond pulsed electric field ablation has been widely applied in clinical cancer treatment, while its molecular mechanism is still unclear. Researchers have revealed that nanosecond pulsed electric field generates nanopores in plasma membrane, leading to a rapid influx of Ca²⁺; it has specific effect on intracellular organelle membranes, resulting in endoplasmic reticulum injuries and mitochondrial membrane potential changes. In addition, it may also change cellular morphology through damage of cytoskeleton. This article reviews the recent research advances on the molecular mechanism of cell membrane and organelle changes induced by nanosecond pulsed electric field ablation.

Electric Double-Layer Capacitor Fabricated with Addition of Carbon Nanotube to Polarizable Electrode

International Nuclear Information System (INIS)

Yoshiyuki, S.

2012-01-01

Electrical double-layer capacitor (EDLC) was fabricated with addition of carbon nano tube (CNT) to polarization electrodes as a conducting material. The CNT addition reduced the series resistance of the EDLC by one-twentieth, while the capacitance was not increased by the CNT addition. The low series resistance leaded to the high electrical energy stored in the EDLC. In this paper, the dependence of the series resistance, the specific capacitance, the energy, and the energy efficiencies on the CNT addition is discussed

AC Electric Field Communication for Human-Area Networking

Science.gov (United States)

Kado, Yuichi; Shinagawa, Mitsuru

We have proposed a human-area networking technology that uses the surface of the human body as a data transmission path and uses an AC electric field signal below the resonant frequency of the human body. This technology aims to achieve a “touch and connect” intuitive form of communication by using the electric field signal that propagates along the surface of the human body, while suppressing both the electric field radiating from the human body and mutual interference. To suppress the radiation field, the frequency of the AC signal that excites the transmitter electrode must be lowered, and the sensitivity of the receiver must be raised while reducing transmission power to its minimally required level. We describe how we are developing AC electric field communication technologies to promote the further evolution of a human-area network in support of ubiquitous services, focusing on three main characteristics, enabling-transceiver technique, application-scenario modeling, and communications quality evaluation. Special attention is paid to the relationship between electro-magnetic compatibility evaluation and regulations for extremely low-power radio stations based on Japan's Radio Law.

On a Correlation between the Ionospheric Electric Field and the Time Derivative of the Magnetic Field

Directory of Open Access Journals (Sweden)

R. R. Ilma

2012-01-01

Full Text Available A correlation of the ionospheric electric field and the time derivative of the magnetic field was noticed over thirty years ago and has yet to be explained. Here we report on another set of examples during the superstorm of November 2004. The electric field in the equatorial ionosphere, measured with the Jicamarca incoherent scatter radar, exhibited a 3 mV/m electric field pulse that was not seen in the interplanetary medium. It was, however, accompanied by a correlation with the time derivative of the magnetic field measured at two points in Peru. Our inclination was to assume that the field was inductive. However, the time scale of the pulse was too short for the magnetic field to penetrate the crust of the Earth. This means that the area threaded by ∂B/∂t was too small to create the observed electric field by induction. We suggest that the effect was caused by a modulation of the ring current location relative to the Earth due to the electric field. This electric field is required, as the magnetic field lines are considered frozen into the plasma in the magnetosphere. The closer location of the ring current to the Earth in turn increased the magnetic field at the surface.

The chromatographic separation of particles using optical electric fields

DEFF Research Database (Denmark)

Javier Alvarez, Nicolas; Jeppesen, Claus; Yvind, Kresten

2013-01-01

We introduce a new field-flow fractionation (FFF) technique, whereby molecules are separated based on their differential interaction (dielectrophoresis (DEP)) with optical electric fields, i.e. electric fields with frequencies in the visible and near-infrared range. The results show that a parall...

Electromagnetic Analysis and Design of Switched Reluctance Double-Rotor Machine for Hybrid Electric Vehicles

Directory of Open Access Journals (Sweden)

Shouliang Han

2014-10-01

Full Text Available The double-rotor machine is a kind of multiple input and output electromechanical energy transducer with two electrical ports and two mechanical ports, which is an ideal transmission system for hybrid electric vehicles and has a series of advantages such as integration of power and energy, high efficiency and compaction. In this paper, a switched reluctance double-rotor machine (SRDRM is proposed for hybrid electric vehicles, while no conductor or PM in the middle rotor. This machine not only inherits the merits of switched reluctance machine, such as simple salient rotor structure, high reliability and wide speed range, but also can avoid the outer rotor’s cooling problem effectively. By using an equivalent magnetic circuit model, the function of middle rotor yoke is analyzed. Electromagnetic analyses of the SRDRM are performed with analytical calculations and 2-D finite element methods, including the effects of main parameters on performance. Finally, a 4.4 kW prototype machine is designed and manufactured, and the tests are performed, which validate the proposed design method.

Research on a new magnetic-field-modulated brushless double-rotor machine with sinusoidal-permeance modulating ring

Directory of Open Access Journals (Sweden)

Ping Zheng

2017-05-01

Full Text Available The magnetic-field-modulated brushless double-rotor machine (MFM-BDRM, composed of a stator, a modulating ring rotor, and a PM rotor, is a kind of power-split device for hybrid electric vehicles (HEVs. In this paper, a new MFM-BDRM with sinusoidal-permeance modulating ring named Sinusoidal-Permeance-Modulating-Ring Brushless Double-Rotor Machine (SPMR-BDRM is proposed to solve the problem of poor mechanical strength and large iron loss. The structure and the operating principle of the MFM-BDRM are introduced. The design principle of the sinusoidal-permeance modulating ring is analyzed and derived. The main idea of that is to minimize the harmonic permeance of air gap, thereby the harmonic magnetic fields can be restrained. There are comparisons between a MFM-BDRM with sinusoidal-permeance modulating ring and a same size MFM-BDRM with traditional modulating ring, including magnetic field distributions and electromagnetic performances. Most importantly, the iron losses are compared under six different conditions. The result indicates that the harmonic magnetic fields in the air gap are restrained; the electromagnetic torque and power factor are almost the same with same armature current; the torque ripples of the modulating ring rotor and the PM rotor are reduced; the stator loss is reduced by 13% at least and the PM loss is reduced by 20% at least compared with the same size traditional MFM-BDRM under the same operating conditions.

Studies of the wavelength dependence of non-sequential double ionization of xenon in strong fields

International Nuclear Information System (INIS)

Kaminski, P.; Wiehle, R.; Kamke, W.; Helm, H.; Witzele, B.

2005-01-01

Full text: The non-sequential double ionization of noble gases in strong fields is still a process which is not completely understood. The most challenging question is: what is the dominant physical process behind the knee structure in the yield of doubly charged ions which are produced in the focus of an ultrashort laser pulse in dependence of the intensity? Numerous studies can be explained with the so-called rescattering model, where an electron is freed by the strong laser field and then driven back to its parent ion due to the oscillation of the field. Through this backscattering process it is possible to kick out a second electron. However in the low intensity or multiphoton (MPI) region this model predicts that the first electron can not gain enough energy in the oscillating electric field to further ionize or excite the ion. We present experimental results for xenon in the MPI region which show a significant contribution of doubly charged ions. A Ti:sapphire laser system (800 nm, 100 fs) is used to ionize the atoms. The coincident detection of the momentum distribution of the photoelectrons with an imaging spectrometer and the time of flight spectrum of the ions allows a detailed view into the ionization process. For the first time we also show a systematic study of the wavelength dependence (780-830 nm and 1180-1550 nm) on the non-sequential double ionization. The ratio Xe 2+ /Xe + shows a surprising oscillatory behavior with varying wavelength. Ref. 1 (author)

Neuron matters: electric activation of neuronal tissue is dependent on the interaction between the neuron and the electric field.

Science.gov (United States)

Ye, Hui; Steiger, Amanda

2015-08-12

In laboratory research and clinical practice, externally-applied electric fields have been widely used to control neuronal activity. It is generally accepted that neuronal excitability is controlled by electric current that depolarizes or hyperpolarizes the excitable cell membrane. What determines the amount of polarization? Research on the mechanisms of electric stimulation focus on the optimal control of the field properties (frequency, amplitude, and direction of the electric currents) to improve stimulation outcomes. Emerging evidence from modeling and experimental studies support the existence of interactions between the targeted neurons and the externally-applied electric fields. With cell-field interaction, we suggest a two-way process. When a neuron is positioned inside an electric field, the electric field will induce a change in the resting membrane potential by superimposing an electrically-induced transmembrane potential (ITP). At the same time, the electric field can be perturbed and re-distributed by the cell. This cell-field interaction may play a significant role in the overall effects of stimulation. The redistributed field can cause secondary effects to neighboring cells by altering their geometrical pattern and amount of membrane polarization. Neurons excited by the externally-applied electric field can also affect neighboring cells by ephaptic interaction. Both aspects of the cell-field interaction depend on the biophysical properties of the neuronal tissue, including geometric (i.e., size, shape, orientation to the field) and electric (i.e., conductivity and dielectricity) attributes of the cells. The biophysical basis of the cell-field interaction can be explained by the electromagnetism theory. Further experimental and simulation studies on electric stimulation of neuronal tissue should consider the prospect of a cell-field interaction, and a better understanding of tissue inhomogeneity and anisotropy is needed to fully appreciate the neural

Low-frequency transient electric and magnetic fields coupling to child body

International Nuclear Information System (INIS)

Ozen, S.

2008-01-01

Much of the research related to residential electric and magnetic field exposure focuses on cancer risk for children. But until now only little knowledge about coupling of external transient electric and magnetic fields with the child's body at low frequency transients existed. In this study, current densities, in the frequency range from 50 Hz up to 100 kHz, induced by external electric and magnetic fields to child and adult human body, were investigated, as in residential areas, electric and magnetic fields become denser in this frequency band. For the calculations of induced fields and current density, the ellipsoidal body models are used. Current density induced by the external magnetic field (1 μT) and external electric field (1 V/m) is estimated. The results of this study show that the transient electric and magnetic fields would induce higher current density in the child body than power frequency fields with similar field strength. (authors)

Neoclassical transport and radial electric fields in TJ-K

International Nuclear Information System (INIS)

Rahbarnia, K.; Greiner, F.; Ramisch, M.; Stroth, U.; Greiner, F.

2003-01-01

The neoclassical transport is investigated in the torsatron TJ-K, which is operated with a low-temperature plasma. In the low-collisionality regime neoclassical losses are not intrinsically ambipolar, leading to the formation of a radial electric field which acts on both neoclassical and turbulent transport. This electric field is measured with a combination of Langmuir and emissive probes. The data are compared with the ambipolar electric field calculated with an analytic model. The experimental fields are positive and larger than the calculated ones. Direct losses of the fast electrons might explain this discrepancy. (orig.)

Nonlocal Poisson-Fermi double-layer models: Effects of nonuniform ion sizes on double-layer structure

Science.gov (United States)

Xie, Dexuan; Jiang, Yi

2018-05-01

This paper reports a nonuniform ionic size nonlocal Poisson-Fermi double-layer model (nuNPF) and a uniform ionic size nonlocal Poisson-Fermi double-layer model (uNPF) for an electrolyte mixture of multiple ionic species, variable voltages on electrodes, and variable induced charges on boundary segments. The finite element solvers of nuNPF and uNPF are developed and applied to typical double-layer tests defined on a rectangular box, a hollow sphere, and a hollow rectangle with a charged post. Numerical results show that nuNPF can significantly improve the quality of the ionic concentrations and electric fields generated from uNPF, implying that the effect of nonuniform ion sizes is a key consideration in modeling the double-layer structure.

Endogenous Cortical Oscillations Constrain Neuromodulation by Weak Electric Fields

Science.gov (United States)

Schmidt, Stephen L.; Iyengar, Apoorva K.; Foulser, A. Alban; Boyle, Michael R.; Fröhlich, Flavio

2014-01-01

Background Transcranial alternating current stimulation (tACS) is a non-invasive brain stimulation modality that may modulate cognition by enhancing endogenous neocortical oscillations with the application of sine-wave electric fields. Yet, the role of endogenous network activity in enabling and shaping the effects of tACS has remained unclear. Objective We combined optogenetic stimulation and multichannel slice electrophysiology to elucidate how the effect of weak sine-wave electric field depends on the ongoing cortical oscillatory activity. We hypothesized that the structure of the response to stimulation depended on matching the stimulation frequency to the endogenous cortical oscillation. Methods We studied the effect of weak sine-wave electric fields on oscillatory activity in mouse neocortical slices. Optogenetic control of the network activity enabled the generation of in vivo like cortical oscillations for studying the temporal relationship between network activity and sine-wave electric field stimulation. Results Weak electric fields enhanced endogenous oscillations but failed to induce a frequency shift of the ongoing oscillation for stimulation frequencies that were not matched to the endogenous oscillation. This constraint on the effect of electric field stimulation imposed by endogenous network dynamics was limited to the case of weak electric fields targeting in vivo-like network dynamics. Together, these results suggest that the key mechanism of tACS may be enhancing but not overriding of intrinsic network dynamics. Conclusion Our results contribute to understanding the inconsistent tACS results from human studies and propose that stimulation precisely adjusted in frequency to the endogenous oscillations is key to rational design of non-invasive brain stimulation paradigms. PMID:25129402

An Electric Field Test Using the MRI

Czech Academy of Sciences Publication Activity Database

Fiala, P.; Bartušek, Karel

2008-01-01

Roč. 4, č. 7 (2008), s. 701-705 ISSN 1931-7360 Institutional research plan: CEZ:AV0Z20650511 Keywords : MRI * electric field * numerical modeling Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering

Electric and magnetic fields at extremely low frequencies

International Nuclear Information System (INIS)

Anderson, L.E.; Kaune, W.T.

1989-01-01

Whole-body exposure to extremely low frequency (ELF, 30-300 Hz) electric fields may involve effects related to stimulation of the sensory apparatus at the body surface (hair vibration, possible direct neural stimulation) and effects within the body caused by the flow of current. Magnetic fields may interact predominantly by the induction of internal current flow. Biological effects observed in a living organism may depend on the electric fields induced inside the body, possibly on the magnetic fields penetrating into the body, and on the fields acting at the surface of the body. Areas in which effects have been observed often appear to be associated with the nervous system, including altered neuronal excitability and neurochemical changes, altered hormone levels, changes in behavioural responses, and changes in biological rhythms. No studies unequivocably demonstrate deleterious effects of ELF electric or magnetic field exposure on mammalian reproduction and development, but several suggest such effects. Exposure to ELF electric and magnetic fields does produce biological effects. However, except for fields strong enough to induce current densities above the threshold for the stimulation of nerve tissues, there is no consensus as to whether these effects constitute a hazard to human health. Human data from epidemiological studies, including reported effects on cancer promotion, congenital malformations, reproductive performance and general health, though somewhat suggestive of adverse health effects, are not conclusive. 274 refs, 13 figs, 6 tabs

Effects of Radial Electric Fields on ICRF Waves

International Nuclear Information System (INIS)

Phillips, C.K.; Hosea, J.C.; Ono, M.; Wilson, J.R.

2001-01-01

Equilibrium considerations infer that large localized radial electric fields are associated with internal transport barrier structures in tokamaks and other toroidal magnetic confinement configurations. In this paper, the effects of an equilibrium electric field on fast magnetosonic wave propagation are considered in the context of a cold plasma model

Modeling nanowire and double-gate junctionless field-effect transistors

CERN Document Server

Jazaeri, Farzan

2018-01-01

The first book on the topic, this is a comprehensive introduction to the modeling and design of junctionless field effect transistors (FETs). Beginning with a discussion of the advantages and limitations of the technology, the authors also provide a thorough overview of published analytical models for double-gate and nanowire configurations, before offering a general introduction to the EPFL charge-based model of junctionless FETs. Important features are introduced gradually, including nanowire versus double-gate equivalence, technological design space, junctionless FET performances, short channel effects, transcapacitances, asymmetric operation, thermal noise, interface traps, and the junction FET. Additional features compatible with biosensor applications are also discussed. This is a valuable resource for students and researchers looking to understand more about this new and fast developing field.

Static and low frequency electric and magnetic fields

International Nuclear Information System (INIS)

Thommesen, G.; Tynes, T.

1994-01-01

The biological effects of exposure to low frequency electric and magnetic fields are reviewed with the objective of summarizing effects directly relevant to considerations of the health and safety of exposed people. Static and low frequency electric and magnetic fields may elicit biological reactions. Whether exposure to such fields may affect human health at field strengths present in everyday or occupational life is still unsettled. There is unsufficient knowledge to establish any dose concept relevant to health risk. 196 refs., 6 tabs

Noninvasive Deep Brain Stimulation via Temporally Interfering Electric Fields.

Science.gov (United States)

Grossman, Nir; Bono, David; Dedic, Nina; Kodandaramaiah, Suhasa B; Rudenko, Andrii; Suk, Ho-Jun; Cassara, Antonino M; Neufeld, Esra; Kuster, Niels; Tsai, Li-Huei; Pascual-Leone, Alvaro; Boyden, Edward S

2017-06-01

We report a noninvasive strategy for electrically stimulating neurons at depth. By delivering to the brain multiple electric fields at frequencies too high to recruit neural firing, but which differ by a frequency within the dynamic range of neural firing, we can electrically stimulate neurons throughout a region where interference between the multiple fields results in a prominent electric field envelope modulated at the difference frequency. We validated this temporal interference (TI) concept via modeling and physics experiments, and verified that neurons in the living mouse brain could follow the electric field envelope. We demonstrate the utility of TI stimulation by stimulating neurons in the hippocampus of living mice without recruiting neurons of the overlying cortex. Finally, we show that by altering the currents delivered to a set of immobile electrodes, we can steerably evoke different motor patterns in living mice. Copyright © 2017 Elsevier Inc. All rights reserved.

Auroral-zone electric fields from DE-1 and -2 at magnetic conjuctions

International Nuclear Information System (INIS)

Weimer, D.R.

1984-01-01

Nearly simultaneous measurements of auroral zone electric fields are obtained by the Dynamics Explorer spacecraft at altitudes below 900 km and above 4500 km during magnetic conjuctions. The measured electric fields are approximately perpendicular to the magnetic field lines. The north-south meridional electric fields are projected to a common altitude by a mapping function. When plotted as a function of invariant latitude, graphs of the projected electric fields measured by DE-1 and DE-2 show that the large-scale electric field is the same at both altitudes. However, superimposed on the large-scale fields are small-scale features with wavelengths less than 100 km which are larger in magnitude at the higher altitude. Fourier transforms of the electric fields show that the magnitudes depend on wavelength. Outside of the auroral zone the electric field spectrums are nearly identical. But within the auroral zone the spectrums of the high and low altitude electric fields have a ratio which increases with the reciprocal of the wavelength. The small-scale electric field variations are associated with field-aligned currents. These currents are measured with both a plasma instrument and magnetometer on DE-1

Laser ablation of titanium in liquid in external electric field

Energy Technology Data Exchange (ETDEWEB)

Serkov, A.A. [Wave Research Center of A.M. Prokhorov General Physics Institute of the Russian Academy of Sciences, 38, Vavilov Street, 119991 Moscow (Russian Federation); The Federal State Educational Institution of Higher Professional Education, “Moscow Institute of Physics and Technology (State University)”, 9 Institutskiy per., 141700, Dolgoprudny, Moscow Region (Russian Federation); Barmina, E.V., E-mail: barminaev@gmail.com [Wave Research Center of A.M. Prokhorov General Physics Institute of the Russian Academy of Sciences, 38, Vavilov Street, 119991 Moscow (Russian Federation); Shafeev, G.A. [Wave Research Center of A.M. Prokhorov General Physics Institute of the Russian Academy of Sciences, 38, Vavilov Street, 119991 Moscow (Russian Federation); National Research Nuclear University MEPhI (Moscow Engineering Physics Institute), 31, Kashirskoye Highway, 115409 Moscow (Russian Federation); Voronov, V.V. [A.M. Prokhorov General Physics Institute of the Russian Academy of Sciences, 38, Vavilov Street, 119991 Moscow (Russian Federation)

2015-09-01

Highlights: • Ablation of a bulk Ti target by 10 ps laser pulses in liquid is experimentally studied in external DC electric field. • Applied cathodic bias leads to increase in average size of self-organized nanostructures formed upon ablation of titanium target. • Laser ablation of Ti target in external electric field results in generation of elongated titanium oxide nanoparticles. - Abstract: Ablation of a bulk Ti target by 10 ps laser pulses in water is experimentally studied in external DC electric field. It is demonstrated that both lateral size of nanostructures (NS) on Ti surface and their density depend on the electric field applied to the target. Scanning Electron Microscopy of NS reveals the shift of their size distribution function toward larger sizes with applied field (cathodic bias, 25 V DC). Density of mushroom-like NS with applied electric field amounts to 10{sup 10} cm{sup −2}. X-ray diffraction of generated nanoparticles (NPs) shows difference in the crystallographic structure of NPs of non-stoichiometric Ti oxides generated with and without electric field. This conclusion is corroborated with the optical absorption spectroscopy of obtained colloids. Transmission Electron Microscopy of NPs also shows difference in morphology of particles produced with and without cathodic bias. The results are interpreted on the basis of instability of the melt on Ti surface in the electric field.

A miniature sensor for electrical field measurements in dusty planetary atmospheres

International Nuclear Information System (INIS)

Renno, N O; Rogacki, S; Kok, J F; Kirkham, H

2008-01-01

Dusty phenomena such as regular wind-blown dust, dust storms, and dust devils are the most important, currently active, geological processes on Mars. Electric fields larger than 100 kV/m have been measured in terrestrial dusty phenomena. Theoretical calculations predict that, close to the surface, the bulk electric fields in martian dusty phenomena reach the breakdown value of the isolating properties of thin martian air of about a few 10 kV/m. The fact that martian dusty phenomena are electrically active has important implications for dust lifting and atmospheric chemistry. Electric field sensors are usually grounded and distort the electric fields in their vicinity. Grounded sensors also produce large errors when subject to ion currents or impacts from clouds of charged particles. Moreover, they are incapable of providing information about the direction of the electric field, an important quantity. Finally, typical sensors with more than 10 cm of diameter are not capable of measuring electric fields at distances as small as a few cm from the surface. Measurements this close to the surface are necessary for studies of the effects of electric fields on dust lifting. To overcome these shortcomings, we developed the miniature electric-field sensor described in this article.

Electric Double-Layer Capacitor Fabricated with Addition of Carbon Nanotube to Polarizable Electrode

Directory of Open Access Journals (Sweden)

Yoshiyuki Show

2012-01-01

Full Text Available Electrical double-layer capacitor (EDLC was fabricated with addition of carbon nanotube (CNT to polarization electrodes as a conducting material. The CNT addition reduced the series resistance of the EDLC by one-twentieth, while the capacitance was not increased by the CNT addition. The low series resistance leaded to the high electrical energy stored in the EDLC. In this paper, the dependence of the series resistance, the specific capacitance, the energy, and the energy efficiencies on the CNT addition is discussed.

Molecular Simulations of Graphene-Based Electric Double-Layer Capacitors

Science.gov (United States)

Kalluri, Raja K.; Konatham, Deepthi; Striolo, Alberto

2011-03-01

Towards deploying renewable energy sources it is crucial to develop efficient and cost-effective technologies to store electricity. Traditional batteries are plagued by a number of practical problems that at present limit their widespread applicability. One possible solution is represented by electric double-layer capacitors (EDLCs). To deploy EDLCs at the large scale it is necessary to better understand how electrolytes pack and diffuse within narrow charged pores. We present here simulation results for the concentrated aqueous solutions of NaCl, CsCl, and NaI confined within charged graphene-based porous materials. We discuss how the structure of confined water, the salt concentration, the ions size, and the surface charge density determine the accumulation of electrolytes within the porous network. Our results, compared to data available for bulk systems, are critical for relating macroscopic observations to molecular-level properties of the confined working fluids. Research supported by the Department of Energy.

Soap-film flow induced by electric fields in asymmetric frames

Science.gov (United States)

Mollaei, S.; Nasiri, M.; Soltanmohammadi, N.; Shirsavar, R.; Ramos, A.; Amjadi, A.

2018-04-01

Net fluid flow of soap films induced by (ac or dc) electric fields in asymmetric frames is presented. Previous experiments of controllable soap film flow required the simultaneous use of an electrical current passing through the film and an external electric field or the use of nonuniform ac electric fields. Here a single voltage difference generates both the electrical current going through the film and the electric field that actuates on the charge induced on the film. The film is set into global motion due to the broken symmetry that appears by the use of asymmetric frames. If symmetric frames are used, the film flow is not steady but time dependent and irregular. Finally, we study numerically these film flows by employing the model of charge induction in ohmic liquids.

Incompressible Einstein–Maxwell fluids with specified electric fields

Indian Academy of Sciences (India)

The Einstein–Maxwell equations describing static charged spheres with uniform density and variable electric field intensity are studied. The special case of constant electric field is also studied. The evolution of the model is governed by a hypergeometric differential equation which has a general solution in terms of special ...

Numerical simulation of electro-magnetic and flow fields of TiAl melt under electric field

Directory of Open Access Journals (Sweden)

Zhang Yong

2010-08-01

Full Text Available This article aims at building an electromagnetic and fluid model, based on the Maxwell equations and Navier-Stokes equations, in TiAl melt under two electric fields. FEM (Finite Element Method and APDL (ANSYS Parametric Design Language were employed to perform the simulation, model setup, loading and problem solving. The melt in molds of same cross section area with different flakiness ratio (i.e. width/depth under the load of sinusoidal current or pulse current was analyzed to obtain the distribution of electromagnetic field and flow field. The results show that the induced magnetic field occupies sufficiently the domain of the melt in the mold with a flakiness ratio of 5:1. The melt is driven bipolarly from the center in each electric field. It is also found that the pulse electric field actuates the TiAl melt to flow stronger than what the sinusoidal electric field does.

Magnetic field sensor based on double-sided polished fibre-Bragg gratings

International Nuclear Information System (INIS)

Tien, Chuen-Lin; Hwang, Chang-Chou; Liu, Wen-Feng; Chen, Hong-Wei

2009-01-01

A new magnetic field sensor based on double-sided polished fibre-Bragg gratings (FBGs) coated with an iron thin film for measuring magnetic flux density was experimentally demonstrated with the sensitivity of 25.6 nm T −1 . The sensing mechanism is based on the Bragg wavelength shift as the magnetic field is measured by the proposed sensing head. Results of this study present the intensity of the reflected optical signal as a function of the applied strain on the FBG. This paper shows that an improved method for sensing the wavelength shift with changes in external magnetic field is developed by use of the double-sided polished FBGs

Electric field effects in hyperexcitable neural tissue: A review

International Nuclear Information System (INIS)

Durand, D.M.

2003-01-01

Uniform electric fields applied to neural tissue can modulate neuronal excitability with a threshold value of about 1mV mm -1 in normal physiological conditions. However, electric fields could have a lower threshold in conditions where field sensitivity is enhanced, such as those simulating epilepsy. Uniform electrical fields were applied to hippocampal brain slices exposed to picrotoxin, high potassium or low calcium solutions. The results in the low calcium medium show that neuronal activity can be completely blocked in 10% of the 30 slices tested with a field amplitude of 1mV mm -1 . These results suggest that the threshold for this effect is clearly smaller than 1mV mm -1 . The hypothesis that the extracellular resistance could affect the sensitivity to the electrical fields was tested by measuring the effect of the osmolarity of the extracellular solution on the efficacy of the field. A 10% decrease on osmolarity resulted in a 56% decrease ( n =4) in the minimum field required for full suppression. A 14% in osmolarity produced an 81% increase in the minimum field required for full suppression. These results show that the extracellular volume can modulate the efficacy of the field and could lower the threshold field amplitudes to values lower than ∼1mmV mm -. (author)

Effect of Electric Field on Outwardly Propagating Spherical Flame

KAUST Repository

Mannaa, Ossama

2012-06-01

The thesis comprises effects of electric fields on a fundamental study of spheri­cal premixed flame propagation.Outwardly-propagating spherical laminar premixed flames have been investigated in a constant volume combustion vessel by applying au uni-directional electric potential.Direct photography and schlieren techniques have been adopted and captured images were analyzed through image processing. Unstretched laminar burning velocities under the influence of electric fields and their associated Markstein length scales have been determined from outwardly prop­agating spherical flame at a constant pressure. Methane and propane fuels have been tested to assess the effect of electric fields on the differential diffusion of the two fuels.The effects of varying equivalence ratios and applied voltages have been in­vestigated, while the frequency of AC was fixed at 1 KHz. Directional propagating characteristics were analyzed to identify the electric filed effect. The flame morphology varied appreciably under the influence of electric fields which in turn affected the burning rate of mixtures.The flame front was found to propagate much faster toward to the electrode at which the electric fields were supplied while the flame speeds in the other direction were minimally influenced. When the voltage was above 7 KV the combustion is markedly enhanced in the downward direction since intense turbulence is generated and as a result the mixing process or rather the heat and mass transfer within the flame front will be enhanced.The com­bustion pressure for the cases with electric fields increased rapidly during the initial stage of combustion and was relatively higher since the flame front was lengthened in the downward direction.

Pentacene Excitons in Strong Electric Fields.

Science.gov (United States)

Kuhnke, Klaus; Turkowski, Volodymyr; Kabakchiev, Alexander; Lutz, Theresa; Rahman, Talat S; Kern, Klaus

2018-02-05

Electroluminescence spectroscopy of organic semiconductors in the junction of a scanning tunneling microscope (STM) provides access to the polarizability of neutral excited states in a well-characterized molecular geometry. We study the Stark shift of the self-trapped lowest singlet exciton at 1.6 eV in a pentacene nanocrystal. Combination of density functional theory (DFT) and time-dependent DFT (TDDFT) with experiment allows for assignment of the observation to a charge-transfer (CT) exciton. Its charge separation is perpendicular to the applied field, as the measured polarizability is moderate and the electric field in the STM junction is strong enough to dissociate a CT exciton polarized parallel to the applied field. The calculated electric-field-induced anisotropy of the exciton potential energy surface will also be of relevance to photovoltaic applications. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Auroral zone electric fields from DE 1 and 2 at magnetic conjunctions

Science.gov (United States)

Weimer, D. R.; Goertz, C. K.; Gurnett, D. A.; Maynard, N. C.; Burch, J. L.

1985-01-01

Nearly simultaneous measurements of auroral zone electric fields are obtained by the Dynamics Explorer spacecraft at altitudes below 900 km and above 4,500 km during magnetic conjunctions. The measured electric fields are usually perpendicular to the magnetic field lines. The north-south meridional electric fields are projected to a common altitude by a mapping function which accounts for the convergence of the magnetic field lines. When plotted as a function of invariant latitude, graphs of the projected electric fields measured by both DE-1 and DE-2 show that the large-scale electric field is the same at both altitudes, as expected. Superimposed on the large-scale fields, however, are small-scale features with wavelengths less than 100 km which are larger in magnitude at the higher altitude. Fourier transforms of the electric fields show that the magnitudes depend on wavelength. Outside of the auroral zone the electric field spectrums are nearly identical. But within the auroral zone the high and low altitude electric fields have a ratio which increases with the reciprocal of the wavelength. The small-scale electric field variations are associated with field-aligned currents. These currents are measured with both a plasma instrument and magnetometer on DE-1.

Radiation of an electron in an electric field. 1

International Nuclear Information System (INIS)

Fedosov, N.I.; Flesher, G.I.

1976-01-01

The problem of electron radiation in a field of a travelling electric wave is solved by methods of classical electrodynamics. Such a field may serve as a model of a field on the linear accelerator axis. It is shown that the total radiation power, as well as the spectral-angular distribution of the radiation energy of an electron travelling in a longitudinal electric wave coincide with radiation in a stationary uniform electric field with the strength equal to that of the wave at the point where the particle velocity becomes close to the velocity of light [ru

Hydrogenic donor in a quantum well with an electric field

International Nuclear Information System (INIS)

Jayakumar, K.; Balasubramanian, S.; Tomak, M.

1985-08-01

Variational calculations of the binding energy of a hydrogenic donor in a quantum well formed by GaAs and Gasub(1-x)A1sub(x)As with a constant electric field are performed for different electric fields and well widths. A critical electric field is defined and its variation with well width is presented. (author)

Relativistic Bosons in Time-Harmonic Electric Fields

Science.gov (United States)

Buhucianu, Ovidiu; Dariescu, Marina-Aura; Dariescu, Ciprian

2012-02-01

In the present paper, we consider a bi-dimensional thin sample, placed in a strong harmonically oscillating electric field and a static magnetic induction, both directed along the normal to the sample's plane. The Klein-Gordon equation describing the relativistic bosons leads to a Mathieu's type equation for the temporal part of the wave functions. It follows that, for the electric field pulsation inside a computable range, depending on the external fields intensities, the amplitude functions are turning from oscillatory to exponentially growing modes. For ultra-relativistic particles, one can recover the periodic stationary amplitude behavior.

Distributions of electric and elastic fields at domain boundaries

International Nuclear Information System (INIS)

Novak, Josef; Fousek, Jan; Maryska, Jiri; Marvan, Milan

2005-01-01

In this paper we describe the application of the finite element method (FEM) in modelling spatial distributions of electric and elastic fields in a ferroelectric crystals with two domains separated by a 90 deg. domain wall. The domain boundary is idealized as a two-dimensional defect in an electro-elastic continuum. It represents the source of inhomogenity and internal distortion in both elastic and electric fields. The main results are distributions of electric field, strain and mechanical force along the domain boundary

A simplified model of polar cap electric fields