Action Of Electric Field Research Articles

Quantum Photonic Simulation of Spin-Magnetic Field Coupling and Atom-Optical Field Interaction

In this work, we present the physical simulation of the dynamical and topological properties of atom-field quantum interacting systems by means of integrated quantum photonic devices. In particular, we simulate mechanical systems used, for example, for quantum processing and requiring a very complex technology such as a spin-1/2 particle interacting with an external classical time-dependent magnetic field and a two-level atom under the action of an external classical time-dependent electric (optical) field (light-matter interaction). The photonic device consists of integrated optical waveguides supporting two collinear or codirectional modes, which are coupled by integrated optical gratings. We show that the single-photon quantum description of the dynamics of this photonic device is a quantum physical simulation of both aforementioned interacting systems. The two-mode photonic device with a single-photon quantum state represents the quantum system, and the optical grating corresponds to an external field. Likewise, we also present the generation of Aharonov–Anandan geometric phases within this photonic device, which also appear in the simulated systems. On the other hand, this photonic simulator can be regarded as a basic brick for constructing more complex photonic simulators. We present a few examples where optical gratings interacting with several collinear and/or codirectional modes are used in order to illustrate the new possibilities for quantum simulation.

Simulation research on space charge characteristics of zinc oxide varistor

Zinc oxide (ZnO) lightning arresters have good protection performance and have been widely used in power systems. ZnO varistor is the core component of the arrester, and its electrical performance determines the overvoltage protection level of the arrester. ZnO varistor will produce space charge accumulation phenomenon under the action of electric field. In order to study the space charge characteristics of ZnO varistors more deeply, a bipolar carrier transport model considering the change of grain boundary structure was established, and the law of carrier migration in ZnO grain boundaries was simulated. From the three aspects of pressure time, ambient temperature, and depletion layer density, the space charge distribution inside the grain boundary, Schottky barrier height, and grain boundary leakage current are systematically studied.

Intensification of electrohydrodynamic flows using carbon nano-tubes

Study of behaviour of floating up bubbles in the mixture of transformer oil with carbon nanotubes under the action of high electric field was carried out. The possibility of using carbon nanotubes to create hydrodynamic flows in a liquid dielectric at a very low concentration of nanotubes is shown. It is assumed that the mechanism of the formation of flows is the injection of charge from the surface of nanotubes.

Influence of charge emission behaviors of semi-conductive shielding layer on charge accumulation properties of insulation layer for HVDC cable

Space charge accumulation is one of the key factors restricting the manufacture and application of high-voltage direct current (HVDC) cables. Semi-conductive shielding layer plays an important role in uniform electric field in HVDC cable, and its own emission properties directly affect the space charge behaviours in the insulation material. In the paper, charge injection property from semi-conductive layer to insulation layer have been focused emphatically based on experiment and simulation. The charge injection characteristics of semi-conductive layer under two typical electrode configurations of ‘Metal-Insulation layer-Metal’ (M-I-M) and ‘Semi-conductive layer-Insulation layer-Metal’ (S-I-M) have been studied. The conductive current and depolarization current of the insulation layer are compared. Finally, effect of particle size and concentration of carbon black (CB) in the semi-conductive layer on the interfacial electric field has been studied by electric field simulation. The experimental results show that the charge injection from the semi-conductive layer is more obvious under the action of low electric field of 5 kV mm−1 due to effect of CB particles. It can be seen from the depolarizing current curve that the charge injection quantity with S-I interface is greater than that of M-I interface. Further calculation results show that the maximum distortion electric field increases slightly with the increase of CB size. When CB content is 25%, the electric field distortion caused by interface CB particles is about twice of the average electric field (5 kV mm−1), increasing from 9.61 kV mm−1 at 10 nm to 10.15 kV mm−1 at 50 nm. The reduction of CB size in the semi-conductive layer within a certain range is conducive to the reduction of the interface electric field. The maximum distortion field gradually decreases with the increase of CB content at a certain range.

Excellent Bidirectional Adjustable Multistage Resistive Switching Memory in Bi2FeCrO6 Thin Film.

As an important method to further improve the storage density of resistive memory, multistage resistive switching devices have become an important research direction. However, no stable and controllable multistage resistive switching device has been prepared, and the working mechanism is still unclear. Here, a sandwich-structured device is simply prepared by spin coating, with the work layer is the Bi2FeCrO6 thin film. The device can realize bidirectional controllable multistage resistive switching behavior, the biggest on/off ratio is 104, and it can maintain stability without attenuation at 100 times slow loop and 104 times pulse cycle. The analyzes showed that the charged ions formed by defects in the device migrated under the action of an external electric field lead to the Schottky barrier height reversible changed. Which is the key to cause multistage resistive switching behavior. This work is the first report about the voltage control of bidirectional adjustable multistage resistive switching behavior in the Bi2FeCrO6 thin film. The principle of generation is analyzed, and important ideas and insights are provided for the preparation and treatment of related multistage resistive problems.

Electric properties of Mn-substituted Na0.5Bi0.5TiO3 ceramics in unpoled and poled states

ABSTRACT The Mn-substituted NBT ceramics were prepared by the conventional ceramic fabrication technique. X-ray diffraction (XRD) studies indicated the formation of perovskite phase with rhombohedral symmetry and with small amount of second phase. It was found that 0.5mol% and 0.1mol% dopant concentration enhances piezoelectric coefficients of d33 and k33, increases the depolarization temperature Td and decreases the dielectric loss. Dielectric study showed the existence of a diffuse phase transition at Tm ≈ 320°C. It was shown that a prior electric field poling process changes the character of ϵ(T) and tanδ(T) functions, as well as shifts of Td and Tm to higher temperature. The effects are mainly caused by the reinforcement of polarization/domain ordering and by the change of content rhombohedral/tetragonal phases by electric field action. The results were discussed in terms of lattice distortion and change of defect concentration.

Radiation Problems Accompanying Carrier Production by an Electric Field in the Graphene

A number of physical processes that occur in a flat one-dimensional graphene structure under the action of strong time-dependent electric fields are considered. It is assumed that the Dirac model can be applied to the graphene as a subsystem of the general system under consideration, which includes an interaction with quantized electromagnetic field. The Dirac model itself in the external electromagnetic field (in particular, the behavior of charged carriers) is treated nonperturbatively with respect to this field within the framework of strong-field QED with unstable vacuum. This treatment is combined with a kinetic description of the radiation of photons from the electron-hole plasma created from the vacuum under the action of the electric field. An interaction with quantized electromagnetic field is described perturbatively. A significant development of the kinetic equation formalism is presented. A number of specific results are derived in the course of analytical and numerical study of the equations. We believe that some of predicted effects and properties of considered processes may be verified experimentally. Among these effects, it should be noted a characteristic spectral composition anisotropy of the quantum radiation and a possible presence of even harmonics of the external field in the latter radiation.

Effect of an Electric Field on a Lithium Ion in a Channel of the Doped Silicene–Graphite System

Using the method of molecular dynamics, the behavior of a lithium ion under the action of a constant electric field in a channel formed by silicene sheets doped with phosphorus is studied. It is shown that if the intersheet space in doped silicene is 0.6 nm, then a single lithium ion can freely enter a channel located on a graphite substrate (with the layers doped with nitrogen) and move along the channel. It is found that doping element phosphorus has a strengthening effect on silicene. Two-dimensional silicon structures are slightly deformed but not destroyed and remain stable during the entire calculation time (100 ps). It is shown that the roughness of silicene sheets and the volume of the intersheet space in the channel do not increase after the lithium ion passes through it, since the crystalline structure of silicene is preserved.

Spin Resonance in a Quantum Dot at the Edge of a Topological Insulator with the Inclusion of Continuum States

The dynamics of electronic states under the action of a periodic electric field applied to a quantum dot created by magnetic barriers at the one-dimensional edge of a two-dimensional topological insulator based on a HgTe/CdTe quantum well has been studied. A configuration with two discrete levels is considered and transitions to continuum states above barriers are taken into account. The frequency of oscillations of the discrete level populations has been calculated for various field amplitudes. It has been shown numerically and analytically that the inclusion of the continuous spectrum leads to a decrease in the total population of discrete levels in time. The characteristic times of this decrease corresponding to transitions to continuum have been determined. The dynamics of average values of the energy, spin projections, coordinates, local probability density, and local spin density has been calculated. Time-averaged local probability density current that describes the quantum dot escape at transitions to the continuous spectrum has been calculated. The results of this work can be useful for the design of new generations of nanoelectronics and spintronics devices based on topological insulators.

Dielectric Polarization and Electrorheological Response of Poly(ethylaniline)-Coated Reduced Graphene Oxide Nanoflakes with Different Reduction Degrees.

We prepared poly(ethylaniline)-coated graphene oxide nanoflakes and then treated them with different concentrations of hydrazine solution to form dielectric composite nanoflakes having different reduction degrees of reduced graphene oxide core and insulating polyethylaniline shell (PEANI/rGO). The morphology of PEANI/rGO was observed by scanning electron microscopy, while the chemical structure was confirmed by Fourier transform infrared spectroscopy and X-ray photoelectron spectrometer. The influence of reduction degrees on the conductivity, dielectric polarization and electrorheological effect of PEANI/rGO in suspensions was investigated by dielectric spectroscopy and rheological test under electric fields. It shows that the PEANI/rGO has two interfacial polarization processes respectively due to rGO core and PEANI shell. As the number of hydrazine increases, the conductivity and polarization rate of rGO core increase. As a result, the difference between the polarization rate of rGO core and that of the PEANI shell gradually becomes large. This increased difference does not significantly decrease the yield stress but causes the flow instability of PEANI/GO suspensions under the simultaneous action of electric and shear fields.

Coalescence behavior of aqueous drops in water-in-oil emulsions under high-frequency pulsed AC fields

High-frequency pulsed alternating current field (HFPACF) has attracted attentions owing to its excellent performances of eliminating short circuit, saving energy and reducing environmental pollution. To study the coalescence mechanism of aqueous drops in water-in-oil (W/O) emulsions under HFPACF, micro-behavior of dispersed drops for W/O emulsion was monitored by using a self-designed micro-visual model and coalescence mechanism was analyzed by discussing effects of pulse amplitude, pulse frequency, pulse width ratio, demulsifier concentration, aqueous mass ratio of emulsion, and different model oil emulsions. The results show that the dispersed drops coalesce under the action of electric field, and the particle size of dispersed drops increases with the increase of pulse frequency and amplitude. When the pulse frequency or amplitude reach to a critical value, aqueous drops are driven to form water string or water channel between two electrodes which hinders further drops coalescence in other areas. However, with the increase of pulse width ratio, the size of dispersed drops increases slowly. The optimum pulse frequency and pulse amplitude are obtained at 3.9kV and 4.21kHz, respectively, the optimal pulse width range is 54.9%-84.4%. When the concentration of demulsifier is 60mg/L, the synergistic demulsification effect achieves the highest performance. When the aqueous mass ratio of emulsion reaches a high level (over 30%), which means the drops in emulsion have big size, the coalescence performance under the same electric field strength is great. Also, it is discovered that the dispersed drops in Yongping model oil emulsion have difficulty in forming water chains, since there are much asphaltenes and resins in the water-oil interface leading to high strength of film. For Shuanghe oil emulsion drops are prevented from coalescing, because it contains a mass of paraffin, which can stabilize emulsion at low temperature.

Jet motion and fiber properties arising from a parallel electric field in melt-electrospinning

It is well known that the electric field has a great influence on the diameter and properties of fiber prepared via the melt-electrospinning technique. In this paper, two parallel metal discs were introduced to create a controllable electric field in the experiments. In addition, a three-dimensional electric field was calculated by the numerical simulation method and the jet motion was captured by taking advantage of high-speed photography technology. The influences of electric field distribution on the fiber jet, fiber diameter, fiber mat area and fiber crystallinity were studied in an in-depth and systematical manner. Both whipping amplitude and whipping frequency were also used to describe the characteristics of the jet. The above-mentioned results have proven that increasing the distance between the two parallel metal discs leads to the decrease of electric field intensity and the increase of electric field action time on the fiber, which together determine the diameter and crystallinity of the fiber. With the increase of the outer diameter of the upper disc, the distribution of the electric field becomes more uniform, making it capable of steadily controlling the behavior of the jet, and thus effectively reducing the diameter of the fiber and improving the crystallinity of the fiber.

Prebreakdown State and Its Diagnostics in Multilayer 0.55Pb–Mg1/3Nb2/3O3–0.45PbSc1/2Nb1/2O3 Compounds

The determination of the breakdown voltage and the diagnostics of the prebreakdown state of a material is a topical problem of studying characteristics of insulating materials and structures based on them when applying an external electric field. The new effective method of the diagnostics of the prebreakdown state of multilayer structures (MLC) based on the ferroelectric–relaxor 0.55Pb–Mg1/3Nb2/3O3–0.45-PbSc1/2Nb1/2O3 (PMN–PSN) is considered. The method is based on an analysis of the dynamics of changing the MLC surface temperature during applying an external electric field. A series of the MLC samples has been tested under action of electric field E = 10–120 kV/cm and the ambient temperature from room temperature to 80°C. The critical electric field that characterizes the prebreakdown state of the PMN–PSN multilayer structures and, correspondingly, restricts the upper limit of operating voltages for the electrocaloric applications has been determined.

FEATURES OF EXCITATION AND AZIMUTHAL AND MERIDIONAL PROPAGATION OF LONG-PERIOD Pi3 OSCILLATIONS OF THE GEOMAGNETIC FIELD ON DECEMBER 8, 2017

We study the Pi3 pulsations (with a period T=15–30 min) that were recorded on December 8, 2017 at ground stations in the midnight sector of the magnetosphere at the latitude range of DP2 current system convective electrojets. We have found that Pi3 are especially pronounced in the pre-midnight sector with amplitude of up to 300 nT and duration of up to 2.5 hrs. The pulsation amplitude rapidly decreased with decreasing latitude from F′=72° to F′=63°. The event was recorded during the steady magnetospheric convection. In the southward Bz component of the interplanetary magnetic field, irregular oscillations were detected in the Pi3 frequency range. They correspond to slow magnetosonic waves occurring without noticeable variations in the dynamic pressure Pd. Ground-based geomagnetic observations have shown azimuthal propagation of pulsations with a 0.6–10.6 km/s velocity east and west of the midnight meridian. An analysis of the dynamics of pulsations along the meridian has revealed their propagation to the equator at a velocity 0.75–7.87 km/s. In the projection onto the magnetosphere, the velocities are close in magnitude to the observed propagation velocities of substorm injected electrons. In the dawn-side magnetosphere during ground-observed Pi3 pulsations, compression mode oscillations were recorded.
 We conclude that propagation of geomagnetic field oscillations in this event depends on the dynamics of particle injections under the action of a large-scale electric field of magnetospheric convection, which causes the plasma to move to Earth due to reconnection in the magnetotail. Small-scale oscillations in the magnetosphere were secondary, excited by the solar wind oscillations penetrating into the magnetosphere.

Особенности возбуждения и распространения по азимуту и меридиану длиннопериодных Pi3 колебаний геомагнитного поля 8 декабря 2017 г.

We study the Pi3 pulsations (with a period T=15–30 min) that were recorded on December 8, 2017 at ground stations in the midnight sector of the magnetosphere at the latitude range of DP2 current system convective electrojets. We have found that Pi3 are especially pronounced in the pre-midnight sector with amplitude of up to 300 nT and duration of up to 2.5 hrs. The pulsation amplitude rapidly decreased with decreasing latitude from F′=72° to F′=63°. The event was recorded during the steady magnetospheric convection. In the southward Bz component of the interplanetary magnetic field, irregular oscillations were detected in the Pi3 frequency range. They correspond to slow magnetosonic waves occurring without noticeable variations in the dynamic pressure Pd. Ground-based geomagnetic observations have shown azimuthal propagation of pulsations with a 0.6–10.6 km/s velocity east and west of the midnight meridian. An analysis of the dynamics of pulsations along the meridian has revealed their propagation to the equator at a velocity 0.75–7.87 km/s. In the projection onto the magnetosphere, the velocities are close in magnitude to the observed propagation velocities of substorm injected electrons. In the dawn-side magnetosphere during ground-observed Pi3 pulsations, compression mode oscillations were recorded.
 We conclude that propagation of geomagnetic field oscillations in this event depends on the dynamics of particle injections under the action of a large-scale electric field of magnetospheric convection, which causes the plasma to move to Earth due to reconnection in the magnetotail. Small-scale oscillations in the magnetosphere were secondary, excited by the solar wind oscillations penetrating into the magnetosphere.

A Molecular-Level Picture of Electrospinning

Electrospinning is a modern and versatile method of producing nanofibers from polymer solutions or melts by the action of strong electric fields. The complex, multiscale nature of the process hinders its theoretical understanding, especially at the molecular level. The present article aims to contribute to the fundamental picture of the process by the molecular modeling of its nanoscale analogue and complements the picture by laboratory experiments at macroscale. Special attention is given to how the process is influenced by ions. Molecular dynamics (MD) is employed to model the time evolution of a nanodroplet of aqueous poly(ethylene glycol) (PEG) solution on a solid surface in a strong electric field. Two molecular weights of PEG are used, each in 12 aqueous solutions differing by the weight fraction of the polymer and the concentration of added NaCl. Various structural and dynamic quantities are monitored in production trajectories to characterize important features of the process and the effect of ions on it. Complementary experiments are carried out with macroscopic droplets of compositions similar to those used in MD. The behavior of droplets in a strong electric field is monitored using an oscilloscopic method and high-speed camera recording. Oscilloscopic records of voltage and current are used to determine the characteristic onset times of the instability of the meniscus as the times of the first discharge. The results of simulations indicate that, at the molecular level, the process is primarily driven by polarization forces and the role of ionic charge is only minor. Ions enhance the evaporation of solvent and the transport of polymer into the jet. Experimentally measured instability onset times weakly decrease with increasing ionic concentration in solutions with low polymer content. High-speed photography coupled with oscilloscopic measurement shows that the measured instability onset corresponds to the formation of a sharp tip of the Taylor cone. Molecular-scale and macroscopic views of the process are confronted, and challenges for their reconciliation are presented as a route to a true understanding of electrospinning.

Electro-active control of the viscous flow and tribological performance of ecolubricants based on phyllosilicate clay minerals and castor oil

Lubricating fluids with highly improved tribological performance very often entail the use of environmentally disrespectful formulations. Based on organoclay dispersions in castor oil, the present research explores the development of simple and sustainable lubricants that enable an “active control” of the tribological behavior under the action of electric fields. Storage stable formulations with high electro-rheological (ER) performance were obtained with 2 wt% organo-modified montmorillonites (OMt) dispersions in castor oil. Their strong ER potential was assessed through the dynamic yield stress values obtained from steady flow curves at 25 °C under electric fields up to 4 kV/mm. Broadband dielectric spectroscopy measurements demonstrated a local maximum (or shoulder) in the dielectric loss, ε´´, in the frequency range 5–10 kHz which is related to interfacial polarization. It was found that the OMt clays had a much greater ER potential than other types of clay mineral (e.g. halloysite nanotubes) that did not exhibit any polarization relaxation in ε´´. Moreover, in general, a fairly good correlation of the yield stress values with the drop in the permittivity, Δε´ = ε0´ – ε∞´, was found for the OMt clays. Preliminary electro-tribological tests were carried out using a ball-on-three plates setup, with an optimal formulation prototype consisting of 2 wt% Cloisite 15A dispersion in castor oil. The results demonstrated a reduction of up to 9% of the friction coefficient in the mixed lubrication regime. This outcome, based on organo-modified layered nanosilicates dispersions in castor oil, revealed the feasibility of producing a “new generation” of lubricants which, with no need for hazardous chemicals, may assist in the development of a novel concept of lubrication through electric potentials.

Inverse and direct magnetoelectric effects in orthorhombic DyMnO3 manganite single crystals

Correlations between the direct and inverse magnetoelectric effects in orthorhombic DyMnO3 single crystals have been investigated. In the inverse magnetoelectric effect, the magnetic moment of the crystal appears to have a contribution that is sinusoidal oscillating in ac electric fields below the temperature TFE of ferroelectric phase transition. The first and the second harmonics of the inverse magnetoelectric effect are clearly detected. The magnetoelectric susceptibilities α and β, corresponding to first and second harmonics, are found to correlate with the derivative of polarization with respect to the magnetic field. The influence of the magnetic and electric regimes during cooling on magnetoelectric effects has also been studied. The maximum change in the magnetic moment of a sample under the action of electric fields is observed under the same (T, H) conditions as the rotation of the spontaneous polarization vector from the crystallographic c direction to the a axis in the magnetic field H || b.

On the Operation of an Electroacoustic Transducer Based on Electrokinetic Phenomena under Turbulent Fluid Motion

The paper considers equations describing the motion of a fluid in a porous medium under the action of an electric field in conditions of the formed turbulent mode of motion. Equations are given that describe the acoustic oscillations that occur in a fluid, the source of which can be not only an alternating, but also a constant electric field. The pulsating broadband acoustic oscillations arising under the action of a constant electric field can be spurious during the operation of electroacoustic transducers, which should be taken into account in their design. The results of field experiments on the model of an electroacoustic transducer confirm the theoretical results presented in the study. The stated theoretical and experimental results make it possible to solve the priority scientific–technical problem of designing and creating new types of acoustic emitters.

Electric field induced dynamics of viscoplastic droplets in shear flow

We investigate the dynamics of viscoplastic droplets under the combined action of electric field and shear flow by performing direct numerical simulations. The electro-hydrodynamic equations are solved in a two-dimensional finite volume framework, and the interface is captured using a volume-of-fluid approach. The rheology of the viscoplastic droplet is modeled as a Bingham plastic fluid. Both the drop and the surrounding medium are considered to be perfect dielectric fluids. The simulations reveal that in the sole presence of the shear flow, the plasticity of the fluid plays a pivotal role in deciding the magnitude of droplet deformation and orientation. The local viscosity inside the drop is significantly augmented for higher plasticity of the fluid. Under the action of the electric field, the droplet deformation and orientation can be suitably tuned by varying the magnitude of the permittivity contrast between the fluids. The droplets experience enhanced deformation and preferred orientation against the flow direction when the permittivity ratio is greater than unity. Increasing the droplet plasticity leads to reduction in the droplet deformation. Conversely, by increasing the electric field strength, the deformation of the droplets can be notably enhanced, with a stronger response observed for a permittivity ratio beyond unity. Finally, it is observed that by suitably manipulating the strength of the shear flow and the electric field, droplet breakup can be engendered. The mode of droplet disintegration differs due to variation of the parameters, which can be attributed to the competing influence of shear and electric forces on the droplet.