Effect of longitudinal electric field on capillary instability of a thin axisymmetric layer of liquid dielectric coating a dielectric fiber

The flow of a viscous dielectric liquid surrounded with a gas is investigated in the process of capillary disintegration of a thin axisymmetric liquid layer on an undeformable cylindrical dielectric fiber in a uniform electric field is investigated. An asymptotic analysis of the system of equations and hydrodynamic boundary conditions written with allowance for surface ponderomotive forces is carried out for the case when the average thickness of the layer is much smaller than the radius of the fiber cross section. The problem of the transition of the liquid configuration from the state of a stationary cylindrical layer to the hydrodynamic state in the form of a regular sequence of drops is formulated. In this formulation, a nonlinear parabolic equation that describes the evolution of the local thickness of the layer on the time interval to the instant of drop formation is derived. The effect of the key parameters on the capillary instability is analyzed based on the linearized version of the resultant equation and the linearized electrostatic problem of calculating the field perturbations.     

Effect of tangential electric field on the evolution of the Rayleigh-Taylor instability of a dielectric liquid film

The effect of surface ponderomotive forces produced by a uniform tangential electric field on the evolution of the Rayleigh-Taylor instability of an isothermal film of a homogeneous incompressible dielectric liquid coating the lower surface of a horizontal insulating plate is studied in the long-wavelength approximation for the hydrodynamic equations and a simplified system of electrostatics equations. The lower boundary of the liquid is the interface with a stationary gas. It is shown in the framework of the linear theory that during the disruption of the continuous film, ponderomotive forces induce the formation of liquid billows extended along the applied field lines.     

On the instability of conical protrusions of liquid surface in electric field

Electric field is analyzed at the tip of the conical protrusion of a conductive liquid surface that forms as the field strength approaches certain threshold values. When the field exceeds the threshold, the cone tip generally becomes unstable and emits a slender jet. The field strength at the sharp tip of a conducting liquid cone tends to infinity. Even though the field has a singularity, the cone tip becomes unstable only if the semi-cone angle decreases below the Taylor angle, which is the same for all conducting liquids. It is shown that similar conical protrusions can form if the liquid is a dielectric and its permittivity is sufficiently high. In this case, the equilibrium cone angle depends on the permittivity. When the permittivity is lower than approximately 17.60, cones cannot form, and the ensuing phenomena do not occur.     

Dispersion of a charged gas bubble in a liquid dielectric in an electric field

Onsager’s principle of minimum energy dissipation in nonequilibrium processes is applied to calculate the characteristics of a surface-conducting charged bubble breakup in a liquid dielectric in a uniform electrostatic field. The domains of physical parameters are determined in which daughter bubbles are ejected from both apexes and are not ejected from only one apex.     

Deformation of a pretilted nematic liquid crystal layer in an electric field

The deformation of the optical axis of a nematic liquid crystal layer under the influence of an electric field is caused by the dielectric torque. This momentum counteracts with an elastic torque generated by interfacial forces between the surface of the electrode and the liquid crystal. By means of a variational analysis, the deformation profiles within the liquid crystal layer are calculated, assuming large interfacial energies and various angles of pretilt of the liquid crystal directors with respect to the electrodes. Both the extreme case of a homeotropic (vertical) alignment on one electrode and a homogeneous (parallel) alignment on the opposite electrode, as well as the general case of arbitrary and different alignments on both electrodes, lead to heavily pretilted liquid crystal layers, resulting in definite deformation profiles without disclinations. Liquid crystal cells prepared in this way neither show threshold voltages nor delay times when electrical fields are applied. Measured and calculated characteristics of such liquid crystal cells are presented, they show good agreement.     

On the motion of charged particles in an alternating nonuniform electric field

The equations of motion for a charged particle in an electric field featuring a stationary and an oscillating component are considered for the case where the force of friction is linear in the particle velocity. The averaging of these equations over the period of field oscillations is legitimate under some specific conditions. The most general expression for an additional stationary force acting on the particle under these conditions is derived, and the limiting values of this force are found. Applications of the results obtained in the present study are considered. Such applications include the use of pulsed currents in the electrochemical dimensional treatment of materials.     

On dynamic excitation of Marangoni instability in a liquid layer with insoluble surfactant on the deformable surface

The European Physical Journal Special Topics - This paper is a continuation of our previous work presented at the IMA-6, see [1]. We continue to analyze the parametric excitation of Marangoni...     

Electroviscous effect in an alternating electric field

Experimental dependence of the relative dynamic viscosities of liquid dielectrics on the applied alternating voltage amplitude and frequency is presented. The voltage frequency was varied from 20 Hz to 2 kHz. The variation of viscosity can be attributed to a change in the liquid structure, with ion-molecule complexes centered at the ions produced as a result of charge injection from an electrode. A change in the injection regime leads to a change in viscosity.     

On the intrinsic quadrupole electric field of a centrosymmetric dielectric

In agreement with a prediction of the theory, we have observed experimentally the intrinsic quadrupole electric field of a centrosymmetric crystal. Pis’ma Zh. éksp. Teor. Fiz. 67, No. 1, 15–20 (10 January 1998)     

Polaron in a strong alternating electric field

The solution is found for the transport equation for a Feynman polaron having arbitrary coupling interacting with the acoustic oscillations in an alternating electric field. In the low-frequency case, this solution cannot be normalized — there are runaway polarons. For high frequencies, this effect is absent. Equations are obtained for the electrical conductivity of polaron semiconductors for various particular cases, including the runaway regime.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 4, pp. 45–49, April, 1979.     

Weakly conductive anisotropic media in an alternating electric field

The problem of finding the potential function in a weakly conductive anisotropic medium for an assigned distribution of the potential on the boundary and sinusoidal variation with time is solved. It is shown that for each phase of the supply voltage the distribution of the potential is the same as it would be for a static field in an insulating crystal with a nonuniform anisotropy that varies with the phase according to a definite law. Zh. Tekh. Fiz. 68, 71–74 (April 1998)     

On the contactless effect of an electric field on liquid systems

An effect of an electric field on the evaporation of polar and nonpolar liquids (water and a hydrocarbon, respectively) is established. The effect is stronger in the former case.     

Particle production in a slowly alternating electric field

The spectral density of particles produced in a slowly alternating electric field E(t) is calculated. At m²/|eE|?1 the field can be considered as constant, provided |?/E| ? m(|eE|/m²)^{$\text{3}\text{2}$}.     

Degenerate plasma in a half-space under an external alternating electric field near resonance

The behavior of the electric field near the surface of a half-space filled with a degenerate electron gas in an external ac electric field is studied. The resonance case is considered in which the frequency of the external field is close to that of plasma oscillations. The special features of the behavior of the screened field are analyzed for diffuse reflection of electrons from the boundary. It is shown that there are two layers adjoining the surface in which the behavior of the screened field differs significantly.     

Efficiency of particle charging by an alternating electric field charger

Alternating electric field charger is a device in which the particles are charged by ionic current and periodically deflected by alternating electric field during their flow through the charger. The oscillatory motion of small amplitude reduces the particle loss within the charger. The results of measurements of mean charge of the particles at the outlet and their penetration through the charger are presented in the paper.     

Plasma in a metal layer exposed to an RF electric field

The response of electrons in a metal layer (sheet) to a variable electric field normal to the surface is studied under resonance conditions, i.e., when the frequency of the field is close to the plasma oscillation frequency. The electromagnetic field energy absorbed in the sheet is calculated.     

On the instability of the one-dimensional Peierls insulator in uniform electric field

Behaviour of the quasi-one-dimensional Peierls insulator (PI) with a doubled lattice period (of the trans-polyacetylene type) is studied in the uniform electric field The electric field polarizes the insulator thus decreasing the gap Δ in the quasiparticle spectrum and creates by tunnelling charge carriers pairs. Depending on the field strength direct creation of soliton-antisoliton pairs or electron-hole pairs (e-h) takes place. The (e-h) pairs deform the lattice forming polarons. For the cis-type polyacetylene the superinsulator phase with soliton confinement exists. The latter is characterized by a great number of soliton-antisoliton quantum levels. Because of the charges generation the process of insulator-to-metal transition becomes continuous.     

Surface flow of liquid in an electric field

An analytic solution is proposed for a model problem which demonstrates the occurrence of a surface flow of weakly conducting liquid in an electric field which was previously observed experimentally by the author. Zh. Tekh. Fiz. 69, 127–128 (June 1999)