Electrostatic Field Intensity Research Articles

Optical transitions in semiconductor nanospherical core/shell/shell heterostructure in the presence of radial electrostatic field

The electronic states and optical properties of spherical nanolayer in the presence of the electrostatic radial field in the strong size quantization regime have been considered. Both analytical and numerical methods have been applied to the problem of one-electron states in the system. According to the intensity of the external electrostatic field, three regimes have been distinguished: week, intermediate and strong. Perturbative approach have been applied to the case of week, WKB to the case of intermediate and variation approach to the case of strong field intensities. The analytical dependencies of the one electron energy and wave function on the electric field value and geometrical parameters of the nanolayer have been achieved. The comparison of the results obtained by the analytical method with the results of the numerical method have been made. The interband and intraband optical transitions caused by incident optical light polarized in z direction have been considered in this system. The selection rules for this transitions have been obtained. The dependence of the absorption coefficient on the energy of incident light for both cases of interband and intraband transitions for every regime of the electrostatic field value have been received.

Release Behavior of Polymeric Vesicles in Solution Controlled by External Electrostatic Field.

We found that the polymeric vesicles from the self-assembly of amphiphilic block copolymer polystyrene-block-poly(acrylic acid) (PS144-b-PAA22) in the dioxane/water mixture can be deformed, broken and finally divided into smaller ones via the external electrostatic field. The higher the electrostatic field intensity, the smaller the vesicles. More importantly, this fission phenomenon induced by electrostatic field can be used to control the release behavior of the vesicles. Our experimental results show that the Nile Red (NR) molecules encapsulated inside the cavity of vesicles can be accurately released by controlling the electrostatic field intensity and the release time. These findings not only enrich the knowledge for the external field induced transformation of polymer structures, but also provide a new and highly convenient approach for the controllable release of polymersomes in solution.

STUDY OF ELECTROSTATIC DISPERSION

The article deals with the problems of studying the process of dispersing liquid fuel and water-fuel emulsions, in particular the characteristics of the dispersed spray in high-potential electrostatic fields. The paper deals with the development of a research method for disperse characteristics of liquid fuels, in particular, the changes in the diameter of the spray particles of liquid fuels and water-fuel emulsions based on them, depending on the intensity of high-grade electrostatic field. These studies are relevant in the creation of new devices based on new dispersion, which are not currently used for fuel atomization and combustion devices, in particular based on the electrostatic dispersion. The currently available methods for assessing dispersion are based on the evaluation of the particle diameter, which are formed by dispersing (particle breakage) of the liquid fuel. The views expressed in the course of the study suggest that the dependence of the particle diameter from the electrostatic field can be estimated not only in case of the destruction of the particles (dispersion), but also in case of the formation (growth) of drops during the expiration of the capillary. In order to confirm the provisions the authors developed the installation and technique to study the changes in the dispersion in dependence with the voltage value of high potential electrostatic field. The results of experimental studies are presented and experimental graphics are built for F5 bunker fuel and water-oil emulsions with different concentrations based on it. On the basis of the experimental data processed by correlation analysis method the authors obtained the mathematical model of diameter changes of the particles under the influence of an electrostatic field, which corresponds to the theory of electrostatic dispersion. The developed technique greatly simplifies the determination of the disperse characteristics of liquid fuel in case of electro-static dispersion.

On the calculation of the electrostatic field intensity of an oscillating uncharged drop

The analytical expression is derived for the electric field intensity of an oscillating uncharged drop of nonviscous conductive liquid under an electrostatic field in a linear approximation relative to the disturbance amplitude. Estimates of the field intensity values both in a wave approximation (at long distances from the drop) and in a quasistationary approximation (near the surface of the drop) are performed.

On the equilibrium shape of a charged drop in an electrostatic field

It is found analytically that the equilibrium shape of a charged drop in a uniform electrostatic field in calculations of the first order of smallness for the size of stationary deformation can be considered to be spheroidal, and its eccentricity depends on the charge size and on the intensity of an external electrostatic field. On the threshold of losing stability in relation to the superposition of its own and polarizing charges, the square of the equilibrium eccentricity of a strongly charged drop in a weak field is up to 0.34, and the square equilibrium eccentricity of a weakly charged drop in a strong field is up to 0.78 (in terms of opportunity to realize instability).

Modeling and Experimental Verification of TIGBT Detailed Internal Electric Fields Which Lead to Breakdown

Distribution and intensity of electrostatic field in a trench insulated gate bipolar transistor, a key factor in the breakdown of such power semiconductor devices, are investigated using the variational thermodynamic methodology based on device Helmholtz free energy yielding closed-form solutions. Attention is given to quantifying the detailed field effects due to curvature near the bottom of the gate. Our modeling of the bottom edge of the gate uses the shape of a published scanning electron microscopy image of an as-built trench gate. This necessitates an appropriate approach to represent subtle details of the system. We have also examined the modification of electrostatic field and potential in that region due to oxide charge. The electrostatic field is quantified and described for sheet charges of variable polarity, intensity, and position in the oxide. We have employed Fermi–Dirac statistics instead of Boltzmann statistics, which underconstrain mobile electron and hole populations at the operating conditions of the device studied. Our model results are consistent with the device gate breakdown experiments.

A low subthreshold swing tunneling field effect transistor for next generation low power CMOS applications

We propose a low subthreshold swing transistor architecture called Negative Capacitance Single Gate Silicon-On-Insulator Tunneling Field Effect Transistor (NC-SG-SOI-TFET) and present an analytical model to characterize its performance. Electrostatic potential distribution and electric field intensity in the channel region are obtained by solving the Poisson equation, and the drain current is calculated using the band-to-band carrier generation rate. An additional layer of ferroelectric oxide is used to obtain the negative capacitance. Effect of ferroelectric oxide is incorporated using one-dimensional Landau formalism. Through two dimensional theoretical analysis, we show that the proposed device has superior performance over traditional TFETs in terms of subthreshold swing and short channel effects. For example, a subthreshold swing of 11.82mV/decade and operating voltage of 0.65V for a drain current of 10−8A/µm have been obtained. The physics behind the improved performance is discussed based on the presented model. The analytical model would also be instrumental in designing and optimizing such devices avoiding complexities and cost of numerical models.

A comparative research study concerning the cements composition influence on the durability and physical-mechanical properties of the concretes

The CEM I 42.5 R European cement (SR EN 197-1) and the CD 40 (SR 10092) Romanian road unitary cement with a different content of tricalcium aluminate (C3A): 6.4 and 0.84%, respectively, with a cementation supplement – furnace slag and with an active hydraulic supplement – thermal plant ash, used for the fabrication of road concretes, have been studied. The pH tests, the investigations of the electric conductivity and the Ca2+ ions concentration, have been made out of the cement suspensions in water, as well as the flexural and compression strengths of the concretes obtained with these cements. The tests were made on prismatic specimens (40 × 40 × 160 mm), maintained in water and in aggressive environments with 6000 mg /L MgSO4 and (NH4)2SO4 aqueous solutions. The experimental results demonstrate the dependence of the interaction rate of the studied cements with water, with the cements basicity and also with the electrostatic field intensity of the resulted cations, through the hydration process. A concrete corrosion was noticed in case of CEM I 42.5 R cement and in case of the same cement enhanced with furnace slag and thermal plant ash. A similar influence of the supplements on the mechanical strengths of the samples exposed to aggressive environments was found. The added supplements have a positive role on the studied strengthened binder systems.

A universal method to form Pd nanoparticles on low-surface-area inorganic powders and their support-dependent catalytic activity in hydrogenation of maleic acid

A simple method for preparation of Pd catalysts supported on low-surface-area inorganic powders as carbons, oxides (SiO2, diatomites, WO3, Ta2O5, Nb2O5, V2O5, TiO2, CeO2, ZrO2, Ga2O3, In2O3, Cr2O3, Fe2O3, Al2O3) and salts (CaF2, BaSO4, Ca3(PO4)2) was developed. It implies hydrolytic deposition of Pd(II) precursors onto a support in basic solutions. Regularities of the hydrolysis process without and in the presence of the support are studied by various physicochemical methods. A scheme of the formation of catalytically active component was put forward. Reduced with H2 at 50–120°C, the palladium catalysts demonstrate strong dependence of their specific activity in hydrogenation of aqueous maleic acid on the support nature. TOF value for palladium nanoparticles supported onto an oxide surface slows down with increasing polarizing ability of cations in the lattice of the oxide, that testifies to the influence of the electrostatic field intensity at the support surface on the reaction rate.

Badania procesu separacji elektrostatycznej mieszanin polimerowych o roznych zawartosciach ABS i PMMA

The results of an investigation of the process of electrostatic separation of binary polymeric blends with different content (10, 20, 30, 40, 50, 60, 70, 80, and 90 wt %) of acrylonitrile-butadiene-styrene terpolymer (ABS) and poly(methyl methacrylate) (PMMA) are presented. The separation was carried out by using a home-made prototype of electrostatic cylindrical separator. It was found that the effects of the tribocharging in fluidized bed depended on the process duration. A maximum value of the electric potential (over 22 kV) of the blend containing 50/50 wt % of ABS and PMMA was attained after ca. 20 s of the electrization. Instead, during the mechanical tribocharging, an electric potential increased with the rise of the rotational speed of a stirrer and reached a value of ca. 18 kV. The blend separation was performed in an electrostatic field arising between a high-voltage elliptic electrode and cylindrical ground electrode rotating at a rate of 30 rpm. The dc voltage between the electrodes was 20 kV and the electrostatic field intensity did not exceed 4 kV/cm. It was found that the effects of the separation process, i.e., purity of the particular fractions and yield of the ABS and PMMA recovery, depended on both the tribocharging effects and contents of the individual blend components. A better separation was achieved for the more balanced compositions. The investigations also indicated that the separation of blends containing 20—70 wt % ABS (30—80 wt % PMMA) may result in a purity of the particular fractions above 95 wt % and recovery yield above 97 wt %. Further increase in the purity and yield is possible by application of a multi-step separation.

A theoretical approach to the study of saturation phenomena of electrostatic collection efficiency of 218Po

Radon monitors based on electrostatic collection have been widely used in different radon studies. Collection efficiency of this kind of instrument first depends on the cell geometry and electrostatic field intensity. In the process of new instrument development, some researchers found that electrostatic collection efficiency of 218Po was almost saturated when the voltage between the cylindrical vessel and the detector was higher than 1500V. In this paper, we analyze the physical processes of the freshly positively charged 218Po formed from the α decay of 222Rn and the neutralization kinetics for positively charged 218Po cluster. The analytical expressions of the collection probability of any freshly positively charged 218Po cluster and the total collection efficiency in electrostatic collection cell are obtained. The ratio of the relative growth rate of the collection efficiency to the relative growth rate of the voltage is inversely proportional to the voltage. Such an approach is useful to understand the mechanism of the electrostatic collection of 218Po.

Numerical Simulation of Thermodynamic, Microstructural, and Electric Characteristics of Convective Clouds at the Growth and Mature Stages

Numerical calculations of convective-cloud formation during unstable atmospheric stratification and background wind are performed using the author’s three-dimensional nonstationary model with detailed allowance for hydrodynamic, thermodynamic, microphysical, and electric processes. Formation of the positive and negative volume electric charges is studied and the electric field is calculated at various cloud-development stages. The obtained electrostatic-field intensity is used for correction of the cloud-particle coagulation coefficient which increases in the presence of the field and the charges. It is found that the precipitation-particle growth time in an intense convective cloud is decreased by 20–30 % due to electric coagulation.

超导态零电阻特性形成条件和相图解释

自从1986年发现高温超导体以来，令人兴奋也存在困惑，过去非常成功的超导理论却不能全面解释相图。为探索解释相图，从超导态零电阻特性入手，以超导电子配对机制为线索，抓住零电阻状态必定存在没有电场的通路，也就是在通路内电场强度处处为零；根据光电效应或者量子隧穿现象，当电子逸出后必定留下空穴，并且这些空穴一定在每一个原子核周围形成空穴电场，因而使每一个原子核周围可以出现合电场强度等于零的空间区域。应用静电场高斯定理，求出了核外合电场强度，找到了合电场强度等于零的条件。当相邻原子之间合电场强度等于零的球面相切或相交时，便形成了整块材料内零场强的通路，出现超导态零电阻特性。依据零场强通路的条件解释了令人困惑的p型和n型材料高温超导相图及多超导态。以核外电子在合电场中受力，建立了合力运动方程，求出了能量解，当空穴数量满足解中电子的电位能大于零时，电子具有正能级，而非负能级，电子从正能级激发到零能级便产生了赝能隙。根据超导电子配对机制和零场强通路的条件，提出了室温超导材料的研制方向。 Since the high-temperature superconductivity had been discovered in 1986, people are being excited, but they are being bemused, because the successful theory of superconductivity in the past could not fully explain the superconductivity phase diagrams. Therefore, revealing the physical mechanism and developing room temperature superconducting materials have become an important orientation of scientists. In order to explore the interpretation of phase diagram, it is to begin from the zero-resistance of the superconducting state, to hold this main point that the appearing zero-resistance necessarily exists in a thoroughfare of no electrostatic field, or electrostatic field intensity everywhere equals zero in the thoroughfare; according to photoelectric effect or quantum tunneling, after any electron being emitted, a hole carrier is left necessarily, and it generates electrostatic field of the hole carrier around every atomic nucleus, thus a spherical surface that vector sum of electrostatic field intensity equals zero can appear around every atomic nucleus. To apply the Gauss theorem of electrostatic field, the expression of vector sum of electrostatic field intensity and vector sum to zero equaling qualifications have been derived. When the spherical surfaces of adjacent atoms with zero sum-vector are tangent or intersecting, no electrostatic field thoroughfare is formed within the whole piece of material, and the zero-resistance characteristics of the superconducting state are showed. Qualifications of the no electrostatic field, thoroughfare can explain the bemusement about the high-temperature phase diagram and the multi-superconducting state of the p-type and n-type materials. According to the force for a electron in the sum of electrostatic field, the motion equations of the composite force is established, then the energy solution is found. When hole carrier number is satisfied to that the electronic potential energy is bigger than zero in the solution, the electron has a positive energy level, but has not a normal minus energy level. When the electron has been moved from the positive energy level to the zero energy level, the pseudogap has been generated. According to qualifications of the no electrostatic field thoroughfare, a way to explore the room-temperature superconducting materials has been proposed.

Методика расчета напряженности электростатического поля в изоляции многожильных кабелей

Calculation method of electrostatic field intensity penetrating into insulation of cables’ strands, allowing consider partial penetration of this field into insulation of cable’s separate elements, and, therefore, to lower the field intensity measurement error, arising at such influence of fields is stated. It allows predict fire safety of multicore cables.

Fabrication of aligned lamellar porous alumina using directional solidification of aqueous slurries with an applied electrostatic field

A novel method combining directional solidification of aqueous slurries with an applied electrostatic field was used to fabricate aligned porous alumina scaffolds. A temperature gradient of 1 °C/mm induced a vertical solidification direction. The angle between the temperature gradient and the applied electrostatic field was 90°. As the electrostatic field intensity was increased from 10 to 100 kV/m, the average lamellar spacing of the porous alumina increased from 53.2 to 278.5 μm, and the angle of the lamellar pore channels changed from 7.5° to 52.6° compared to the direction of the temperature gradient. The direction of the lamellar pore channels was a vector sum of the temperature gradient and the electrostatic field intensity. The fabrication of porous alumina with an ordered, lamellar structure can be readily controlled using directional solidification combined with an applied electrostatic field.

Calculation of Externally Applied Electric Field Intensity for Disruption of Cancer Cell Proliferation

It is already known that electrostatic, magnetostatic, extremely low-frequency electric fields, and pulsed electric field could be utilized in cancer treatment. The healing effect depends on frequency and amplitude of electric field. In the present work, a simple theoretical model is developed to estimate the intensity of electrostatic field that damages a living cell during division. By this model, it is shown that magnification of electric field in the bottleneck of dividing cell is enough to break chemical bounds between molecules by an avalanche process. Our model shows that the externally applied electric field of 4 V/cm intensity is able to hurt a cancer cell at the dividing stage.

Suppression of particle deposition onto downstream wall in an AC Electrostatic Precipitator with neutralisation

Electrostatic Precipitators (ESPs) are used to decontaminate polluted environment around the tunnels. A conventional ESP has high collection efficiency but still has a problem in that its downstream walls are polluted due to particle deposition. The experiments carried out in this study have focused on how the particle deposition can be prevented by neutralising the gases. The collection efficiency as a function of particle diameter and the amount of deposited particles on the wall were studied on three types of the ESP: the universal ESP under DC operating mode (DCESP), the ESP under AC operating mode (ACESP) and the ACESP with gas-neutralising equipment (ACESP with neutralisation). Electrostatic field intensity and ion concentration were also measured to understand the state of neutralising the gases. The ACESP, an invention of the authors, prevents particle re-entrainment. The ACESP with neutralisation, which not only prevents the particle re-entrainment but also decreases the charge amount of the downstream gases, was most effective in decreasing the amount of deposited particles.

Quantitative Analysis of 2-D Electrostatic Potential Distributions in 90-nm Si pMOSFETs Using Off-Axis Electron Holography

Off-axis electron holography has been used for quantitative analysis of 2-D electrostatic potential distributions in 90-nm Si p-channel MOSFETs (pMOSFETs). The sample preparation for electron holography is based on focused-ion-beam (FIB) and low-energy (3 keV) Ar-ion backside milling. The measured electrostatic potentials from two pMOSFETs with different offset spacer oxide widths are compared in terms of the separation of extension junctions and source/drain (S/D) junctions. The metallurgical gate length (L <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">met</sub> ) and the S/D junction encroachment (deltaL) under the gate are measured and compared for the two devices. The electrostatic potential abruptness and electric field intensity are investigated around the drain side, and the lateral and vertical electric field intensities are also compared.

Birefringence dispersion of N-(4-methoxybenzylidene)-4-butylaniline (MBBA) determined from channeled spectra

The birefringence of MBBA, determined from the channeled spectra, decreases when the wavelength increases, showing a normal dispersion. The changes induced by an external electrostatic field acting perpendicular on the nematic director in the birefringence values were evidenced. The birefringence increases with the electrostatic field intensity which enhances the preferential alignment by the big values of the electric dipole moments induced parallel to the long MBBA molecule. The main refractive indices were interferometrically measured for three visible monochromatic radiations and the birefringence values were concordant with those estimated from the channeled spectra. The main molecular polarizabilities were estimated.

Effects of Electrostatic Field Intensity on Crystal Structure and Morphology of PVDF Fibers and Films

Samples of melt-cast films and melt-spun poly(vinylidene fluoride) (PVDF) fibers were treated at various electrostatic field intensities. Their crystal structure and morphologies were investigated using wide-angle X-ray diffraction, scanning electron microscopy, and Fourier transform infrared spectroscopy. The results showed that, the electrostatic field did not affect the crystal structure of PVDF fiber, but the crystal orientation was obviously changed. The crystals along the direction of electrostatic field became thick. The crystal orientation of the film, which was obtained by melting and crystallizing PVDF under an electrostatic field, was changed along the direction of electrostatic field. The crystal orientation was the same as the direction of the electrostatic field, but their structures were much more compact. The dipole moment was along the direction of the electrostatic field after the fiber or film had been treated in the electrostatic field