Homogeneous Electrostatic Field Research Articles

On the Issue of Calculating the Magnitude of Induced Charges and the Electrostatic Dipole of an Oblate Spheroid with an Axis of Symmetry Collinear to the External Homogeneous Electrostatic Field

On the Issue of Calculating the Magnitude of Induced Charges and the Electrostatic Dipole of an Oblate Spheroid with an Axis of Symmetry Collinear to the External Homogeneous Electrostatic Field

On the Interaction of Azimuthal Modes of Capillary Waves on the Surface of an Elliptic Jet in a Homogeneous Electrostatic Field

On the Interaction of Azimuthal Modes of Capillary Waves on the Surface of an Elliptic Jet in a Homogeneous Electrostatic Field

On the Calculation of the Magnitude of Induced Charges and the Electrostatic Dipole of an Oblate Spheroid with an Axis of Symmetry Collinear to an External Homogeneous Electrostatic Field

The values of the surface induced charges, the positions of their centers and the value of the equivalent dipole of an oblate conducting spheroid are determined by transition from spheroidal coordinates to a spherical system of coordinates in the analytical asymptotic calculations of the first order of smallness with respect to the squared eccentricity. The characteristics of the equivalent dipole are obtained depending on the value of the electrostatic field strength, squared eccentricity, and the radius of an equal sphere.

Influence of asymmetric surface screening conditions on vortex switching in a ferroelectric nanodot

The behaviors of vortex switching in a ferroelectric nanodot on different surface screening conditions are investigated by phase-field simulations. It is found that asymmetric electrical boundary conditions have a significant effect on the formation of vortex domain structures and play a deterministic role in manipulating the vortex chirality by a homogeneous electrostatic field. The results indicate that the critical electric field for vortex switching can be greatly reduced by engineering the asymmetric surface screening conditions in a ferroelectric nanodot with a regular structure and uniform composition.

TESTING OF NUMERICAL SOLUTION OF THE PROBLEM OF DETERMINING SOURCES OF MAGNETOSTATIC FIELD IN MAGNETIZED MEDIUM

Purpose. Testing of numerical solution algorithm for integral equation for calculation of plane meridian magnetostatic field source distribution at interfaces of piecewise homogeneous magnetized medium by means of electrostatic analogy. Methodology. The piecewise homogeneous medium consists of three regions with different magnetic permeabilities: the shell of arbitrary meridian section, external unlimited medium outside the shell, and the medium inside the shell. For testing external homogeneous magnetic field effect on spherical shell is considered. The analytical solution of this problem on the basis of electrostatic analogy from the solution of the problem uniform electrostatic field effect on dielectric shell is obtained. We have compared results of numerical solution of integral equation with the data obtained by means of analytical solution at the variation of magnetic permeabilities of regions of medium. Results. Integral equation and the algorithm of its numerical solution for calculation of source field distribution at the boundaries of piecewise homogeneous medium is validated. Testing of integral equations correctness for calculation of fictitious magnetic charges distribution on axisymmetric boundaries of piecewise homogeneous magnetized medium and algorithms of their numerical solutions can be carried out by means of analytical solutions of problems of homogeneous electrostatic field effect analysis on piecewise homogeneous dielectric medium with central symmetry of boundaries – single-layer and multilayer spherical shells. In the case of spherical shell in wide range of values of the parameter λk, including close to ± 1, numerical solution of integral equation is stable, and relative error in calculating of fictitious magnetic charges surface density and magnetic field intensity inside the shell is from tenths of a percent up to several percent except for the cases of very small values of these quantities. Originality. The use analytical solutions for problems of calculation of external electrostatic field effect on piecewise homogeneous dielectric bodies for testing integral equations of magnetostatics and algorithms for their numerical solutions. Practical value. The described method of testing integral equations of magnetostatics and their numerical solutions can be used for calculation of magnetic fields of spacecraft control system electromagnets.

Study on charge storage characteristics of PP film electret charged by interface polarization method

Electret attracts increasing attention nowadays because of its lasting and stable electrostatic field. To achieve the widespread use of electret material, higher density and better stability of the electret charge storage as well as well-distributed electrostatic field must be ensured at the same time. Based on the mechanism of interface polarization on double-layer media, a novel charging technology for electret is reported in this paper; and PP film is successfully charged through an auxiliary layer to form electret by this proposed method. Effect of charging temperature and charging voltage on the charge storage performance of the as-prepared PP film electret is investigated by means of surface potential measurement. Also its charge storage performance at high temperatures is explored by thermally stimulated discharge technique. Furthermore, its electrostatic field distribution in the directions of X and Y is measured. Results show that the interface polarization charging is more excellent than the corona charging. At a certain temperature, the surface potential of PP film electret increases with increasing charging voltage and both are in a good linear relationship. This is in good agreement with the theoretical analysis in terms of the equation of electret charge accumulation during the charging process. It is shown that in the case of constant charging voltage within the range of 0.53.0 kV, the effect of charging temperature is not obvious when the temperature is below 75 ℃; however, when the temperature is higher than 75 ℃, the surface potential of PP film electret increases with increasing temperature. In addition, its surface potential may change a little with time so it has an excellent charge storage stability. The distribution of its surface potential shows that it exhibits an homogeneous electrostatic field due to interface polarization charging.

Primary basidiospore charge and taxonomy of Agaricomycetes

AbstractThis article deals with the polarity of electrostatic charges that are carried on ballistic basidiospores after their liberation from fruiting bodies. The spores were collected by placing a portable device beneath the basidiome and allowing them to fall in a horizontal homogeneous electrostatic field, created by vertical parallel plane electrodes. Thus, the experimental setup enabled to investigate the primary charges, the charges present on spores immediately after the release from spore bearing cells. Spores of 135 basidiomes of 50 species of hymenomycetous fungi were collected in various natural conditions. The non-turgescent (drying up, collapsing or ceasing to sporulate) basidiomes were excluded from the taxonomical analysis; the 128 turgescent basidiomes (223 spore samples) of 47 species were taxonomically analyzed. These species represented eight orders (Agaricomycetes, Basidiomycota), covering 21 families and 36 genera. The analysis showed that the spore charges were distributed according to the polarity similarly in all samples in a species, and in a genus. In most cases also genera of one family had the same type of polarity distribution of spore charges. Possibly all taxa from species to monophyletic families are characterized by specific type of polarity of the primary electrostatic charge of basidiospores. Depending on the taxonomical group, all spore charges were negative, positive, or both negative and positive charges were present. This information could be useful in investing the ballistosporic discharge mechanism and for constructing higher-level phylogeny.

Emission rate of charged spores in basidiomycetous fungi and the relaxation time of their electric charges

Basidiospores are one of the main components of coarse fraction of atmospheric aerosol. Majority of them, the ballistospores of 20,000 species of Basidiomycotina, carry electrostatic charges when getting airborne. To study the polarity and magnitude of primary charges and the hymenial emission rate of charged spores, 128 spore samples of 31 species of Agaricomycetes were collected in natural conditions. A portable device was placed under the fruiting body and the freely falling charged spores were extracted from the air by a horizontal homogeneous electrostatic field. The charge polarity distribution was the same in all intraspecies spore samples; it was unipolar-positive, unipolar-negative, or bipolar, depending on the species. The mean spore charge magnitude was 21–981 e, and it was not related to the emission rate of charged spores. The hymenial emission rate was fluctuating, and the maximum value was 715 charged spores cm−2 s−1. To estimate the territorial emission rate of charged spores, area of the hymenial surface per hectare of forest was calculated for three species and the maximum values were 11 m2 ha−1 and 8.6 × 107 charged spores ha−1 s−1. Calculations showed that a spore charge diminished sevenfold within 47 min. Ecologists, health and agricultural scientists could be interested in this information. It could be useful by investigating the role of microorganisms in meteorological phenomena and in atmospheric processes in general.

Analytical Consideration Of Quantum-Confined Stark-Effect and Interband Optical Transitions in Semiconductor Quantum Well

In the regime of strong quantization single-electron states are considered theoretically in the wide-band semiconductor film, placed in a homogeneous electrostatic field. For a certain range of values of the external field, explicit expressions were obtained for the energy spectrum and envelope wave functions of charge carriers in the film. The dependence of the parameters of direct interband electro-optical transitions in the film on the intensity of the external field and the effective mass of charge carriers was also considered.

Optical absorption in a narrow-band InSb cylindrical layered nanowire in the presence of strong electrostatic field

On the example of InSb we consider the influence of a strong homogeneous electrostatic field on the state of carriers in a narrow-band quantized cylindrical layer in the case of Kaine dispersion law. Explicit expressions for the energy spectrum and wave function envelopes of charge carriers in the heterolayer are obtained. It is shown that under action of the strong external field the rotational motion, with respect to angular variables, of charge carriers becomes oscillatory in a narrow cone of the azimuth angle. We have obtained corresponding selection rules and calculated the threshold frequencies of absorption for interband and intraband electro-optical transitions in the layer. The threshold frequencies are determined by the geometric sizes of the sample and the magnitude of the external field.

On Ejecting Colloids Against Capillarity from Sub‐micrometer Openings: On‐Demand Dielectrophoretic Nanoprinting

The printing of liquids and colloids has a large range of applications and often relies on the ability to eject in a controlled manner very small amounts of liquid from the opening of a capillary. To this end, in the conventional on-demand microprinting methods (such as ink-jet piezoelectric or bubble jet) since the liquid wets the inner wall of the capillary, the corresponding capillary pressure at the opening needs to be overcome and the meniscus accordingly deformed to the point where microdroplets are generated and ejected. However, this is prohibitively diffi cult in the sub-micrometer range, due to the large resisting capillary pressure at the ejection opening. This pressure is in the range of O(10 bar) for typical colloidal solvents for an orifi ce diameter of O(100 nm). Ink-jet printing of colloids for 2D and 3D structure generation, [ 1–3 ] on fl exible or infl exible substrates, [ 4 , 5 ] is, among other applications, an alternative approach to mask-based photolithographic microfabrication, but as stated above, also remains a challenge due to the high ejection pressure required for ultrasmall nozzle openings. Printing by electrohydrodynamic jetting profi ting from Taylor-cone [ 6 ] concentrated jet or serial droplet ejection [ 7 ] is a viable option for micrometer size pattern generation of conductive [ 8–10 ] and even biological materials. [ 11 ] The caveat is that this valuable technology relies on ionic liquids and/or charged particles [ 12 ] in the printing suspension, with possible unwanted side effects due to the effective charge deposition on surfaces and that the generated droplets at the tip of the Taylor-cone are not easy to precisely control. While uncharged particles of a colloidal suspension in nonpolar liquid environment cannot be manipulated by a homogeneous electrostatic fi eld, an inhomogeneous fi eld exerts a force FDE P ∝ ∇ |E | on a particle if its polarizability exceeds the polarizability of the surrounding carrier liquid. This is the effect of dielectrophoresis (DEP) [ 13 ] and has been employed for single particle manipulation in electrolyte liquids such as carbon nanotube placement, [ 14 ] separation, [ 15 ] and particle alignment [ 16–19 ]

Nonlinear oscillations of a charged drop levitated in gravity and electrostatic fields

Analytically, on the basis of asymptotic methods, the problem of the nonlinear oscillations of a charged ideal incompressible electroconductive fluid drop levitated at rest in gravity and homogeneous electrostatic fields is solved in the quadratic approximation in two small parameters: the initial drop shape deformation amplitude and the stationary eccentricity of the equilibrium drop shape in the electrostatic field. The calculations are performed in fractional powers of the nonlinear oscillation amplitude. The nonlinear corrections to the oscillation frequencies are always negative and already present in the second-order approximation due to the stationary deformation of the drop in the external fields rather than nonlinear interaction between the modes. In the case considered, in contrast to the nonlinear oscillations of a free charged drop, the expression for the generator of the nonlinearly oscillating drop shape contains terms proportional to the oscillation amplitude to the power 3/2.

(Nb2W4O19), TMA2, Na4(OH2)14(SO4): A New Layered Structure with Lindqvist Heteropolyanions, XAS Characterization of the HPAs.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.

(Nb2W4O19), TMA2, Na4(OH2)14(SO4): a new layered structure with Lindqvist heteropolyanions, XAS characterization of the HPAs

The new (Nb2W4O19),TMA2, Na4(OH2)14(SO4) has been evidenced as a minor phase during the Nb2W4O19TMA (tetramethylammonium) salt synthesis. Its crystal structure has been refined from single crystal X-ray diffraction data, system monoclinic, a=10.166(5) Å, b=17.93(1) Å, c=24.81(1) Å, β=93.057(7)°, space group (S.G.) C2/c, Z=4, R1=3.96%, wR1=4.50%. It shows the stacking of cationic and anionic bidimensional layers. The anionic layer of formula [(Nb2W4O19), TMA2 ]2− is formed of isolated Lindqvist HPAs surrounded by TMA groups. The isolated layers adopt a trigonal symmetry that is lost in the crystal by the association of the cationic sheets. These later, of formula [Na4(OH2)14(SO4)]2+ form porous net-like sheets with nearly circular cavities of diameter 7.5 Å. SO43− groups host the available cavities in a disordered manner. The cohesion between the sheets is performed by both electrostatic interactions and a set of hydrogen bonds. In the cationic layers, the highly symmetrical surrounding of HPAs by TMA groups yields a homogeneous electrostatic field at their external surface leading to a statistic Nb/W disorder over the three available independent metallic positions. Then, XAS experiments at the L1/L3-W edge complementarily helped to highlight the preferential cis configuration of (Nb2W4O19)4− anions, help to the strong Nb vs W contrast in their contribution to the backscattering paths. Previously to these experiments, it was of course checked that both the two phases present in the prepared sample contain Nb2W4O19 anions with nearly unchanged geometry.

Contributions of the substrate electric field to the molecular adsorbate optical nonlinearities

The nonlinear optical response of an adsorbate, whose structure is altered by the inhomogeneous electrostatic field of the substrate, has been evaluated with a particular emphasis on the sum-frequency generation process. In the limiting case of an homogeneous electrostatic field, besides the contributions associated with the induced dipole moments, we have additional contributions which only exist if the adsorbed molecule has permanent dipole moments. Also, the Franck-Condon factors of the unperturbed molecule weight the internal couplings induced by the electrostatic field. For the more general inhomogeneous electrostatic field case, while the main observations remain valid, the Franck-Condon factors are modified by the molecular structure changes induced by the electrostatic field. In addition, we have a strong redistribution of the vibronic couplings resulting from the analytical $\mathbf{Q}$ dependence of the partial charge distribution which is a signature of the field inhomogeneities.

Interaction of hydrogen with a nickel surface in the low-temperature field evaporation

The process of field evaporation of nickel in hydrogen atmosphere under pressure 10 −6 Pa at 20 K was investigated using a high resolution pulsed-laser time-of-flight atom-probe field ion microscope. Under these conditions, the ions of H +, H 2 + and H 3 + were detected as well as those of Ni 2+, Ni + and NiH x + ( x = 1 –3). On the basis of both: experimentally determined energy distribution of ions and ab initio calculations in the density-functional theory (DFT) for Ni–H, including external homogeneous electrostatic fields, we can state that hydrogen atoms are bound to the nickel surface in the presence of the electrostatic field of strength about 30 V/nm. These complex ions are formed within two topmost layers at the nickel surface in the high electric field applied.

Field evaporation of Ir in hydrogen atmosphere

In this paper, some of the data for interaction of Ir atoms with hydrogen in a high electric field obtained with a high-resolution pulsed-laser time-of-flight atom-probe field ion microscope are presented. A model is proposed that under these conditions iridium evaporates in the most part as IrH 2+ and IrH 2 2+ which are subsequently field-dissociated as iridium and hydrogen ions. We present ab initio calculations in a density functional theory for H–Ir, including external homogeneous electrostatic fields, too. The energy barrier for dissociating Ir–H complex decreases gradually with increasing field until it vanishes at about 18 V/nm . The theoretical data obtained are in good agreement with the experiment; our hypothesis can be regarded as highly probable.

The equilibrium shape of a liquid drop in mutually perpendicular electrostatic and hydrodynamic fields

An analysis of the balance of pressures on the surface of a drop of an ideal incompressible liquid, exposed to a homogeneous electrostatic field and streamlined by a laminar flow of an ideal incompressible fluid perpendicular to the field, shows that, in the approximation linear with respect to the deformation amplitude, the equilibrium drop shape represents a triaxial ellipsoid.

Critical conditions for instability of a charged drop moving in an electrostatic field

The pressure balance on the surface of a charged drop of the ideal incompressible liquid freely falling in a homogeneous electrostatic field are analyzed and the critical conditions for instability of the liquid surface are established. Satisfying the criteria found, the values of the drop charge, the electrostatic field strength, and the drop velocity relative to the medium coincide with those observed in thunderstorm clouds. Therefore, the proposed model conditions can be used as a basis in developing a hypothetical mechanism of lightning discharge initiation.

Third-order transport properties of ions in electrostatic fields

Third-order transport properties are calculated through a three-temperature kinetic theory for ions moving in gases under the action of a homogeneous electrostatic field. The analytic procedure is found to be in good agreement with independently obtained numerical results, as well as with calculations from molecular dynamics simulation of the ionic motion. Finally, a relation which enables the calculation of all components of third-order transport coefficients from characteristic integrals of velocity correlation functions is suggested and tested successfully.