Electromagnetic radiation of a nonlinearly oscillating charged drop

Nonlinear oscillations of a charged drop caused by a multimode initial deformation of the equilibrium spherical shape are studied using an asymptotic analytical technique. It is shown that, when the spectrum of modes describing the initial deformation contains two adjacent modes, the center of the drop charge oscillates near the center of mass, which causes the generation of an electromagnetic radiation of the dipole type.     

The acoustic emission from a nonlinearly oscillating charged drop

A charged drop oscillating in a compressible medium is capable of emitting acoustic waves. According to calculations in the constant drop volume approximation linear in the oscillation amplitude, the most intense acoustic emission corresponds to the dominant mode. An acoustic dipole emission related to the excitation of a translational mode is only revealed by calculations in the second order of smallness with respect to the oscillation amplitude, in the case when two adjacent modes are present in the spectrum of initial deformations.     

On the conditions for realization of nonlinear resonance in an oscillating charged drop

Nonlinear oscillations of a charged drop upon the initial deformation of the equilibrium spherical shape representing a superposition of several modes are studied. A condition for the excitation mode frequencies is established under which a resonance interaction of the oscillation modes in the drop takes place. For a drop charged below the critical level for realization of the instability with respect to the intrinsic charge, there is a large number of resonance conditions rather than a single situation, as known previously.     

The effect of intrinsic charge of a nonlinearly oscillating drop on the internal resonance interaction of modes

The resonance interaction of modes in a charged drop performing nonlinear capillary oscillations is weakly sensitive to changes in the intrinsic charge. This is related to a small frequency detuning of these modes in response to the charge variation in a subcritical (according to Rayleigh) region.     

Transverse motion of charged particle with oscillating charge in magnetic field

It is established that a particle bearing an oscillating electric charge can exhibit transverse drift in a homogeneous magnetic field. This drift has a resonance character and cannot be eliminated even at small amplitudes of charge oscillations.     

Evaporation of arbitrary-size drop in electromagnetic radiation field

A theory of the evaporation of an arbitrary-size drop in a field of electromagnetic radiation is constructed using the Lees method. An analytic expression is found for the heat and mass fluxes. An equation describing the change in drop radius as a function of time is obtained.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 34, No. 3, pp. 439–443, March, 1978.     

Inversion of the theory for electromagnetic radiation from charged particles

The problem whether it is possible to calculate from a given radiation field, i.e. with an electric field vector in the wave zone in a given direction and a certain time dependence, the trajectory of a charged particle emitting this field is discussed and solved.     

Nonlinear oscillations of the free surface of a charged drop of a highly viscous liquid

An analytical expression for the shape of a charged drop of a highly viscous, incompressible conducting liquid performing nonlinear axisymmetric oscillations upon a small multimode initial deformation have been obtained by direct expansion within the second order of smallness. Using the obtained expression, it is possible to study the temporal evolution of the shape of initially deformed viscous drops bearing charges that are both sub-and supercritical from the standpoint of the Rayleigh criterion of stability.     

The fundamental mode amplitude buildup in an oscillating drop under internal nonlinear resonance conditions

In a liquid drop charged below the critical level for realization of the instability with respect to the intrinsic charge, the fundamental oscillation mode amplitude can grow due to a nonlinear resonance interaction with higher modes.     

The shape oscillations of a two-dimensional drop including viscous effects

The implementation of a boundary integral method for potential flow is presented for the case of a two-dimensional drop freely oscillating in a vacuum. Calculations using a standard boundary integral formulation and a double-layer potential boundary integral formulation are compared for the case of an inviscid drop with a clean interface. Additional comparisons are made using a least-squares spectral transform method for interpolating and differentiating versus more common methods using cubic splines and central differences. The boundary integral method for potential (i.e. inviscid) flow is extended in two viscous examples to approximate (i) the weak viscous effects in the bulk fluid far from the clean interface, or (ii) the surface viscous effects in an inviscid drop arising from an interface that is highly contaminated with an insoluble surfactant.The addition of an incompressibility constraint, implemented in a least-squares sense, to the standard boundary integral formulation is shown to significantly improve its ability to preserve the conserved quantities of volume and total energy. Nevertheless, the double-layer potential boundary integral formulation, despite its more complicated form, is found to be computationally more efficient than the standard formulation. The use of the least-squares spectral transform method is shown to be more accurate, and in certain conditions more efficient, than using cubic splines and sixth-order central differences for time-evolution of this system. Simulations approximating the damping effects of clean viscous drop are found to be consistent with small deformation theory while the calculations incorporating the damping effects of surface dilatational viscosity are shown to dissipate the energy of the oscillations at a rate that is neither exponential nor algebraic.     

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.     

Using the electrooptic effect to study charge relaxation in colloidal solutions of magnetite

The kinetics of birefringence in a colloidal system of magnetite particles in kerosene under the action of a pulsed electric field has been studied using an electrooptical cell with electrodes covered by a thin insulating film. Rectangular pulses of the field induce jumps in the birefringence signal (at the moments of field switching on and off), which are related to relaxation of the charge formed in the near-electrode region. Experimental data are used to evaluate the characteristic time of near-electrode space charge formation.     

Attenuation of an electromagnetic wave by charged dust particles in a sandstorm

We calculate the light scattering properties of the partially charged dust particles with the Mie theory for electromagnetic waves with different frequencies, and the attenuation coefficients of an electromagnetic wave propagating in a sandstorm are also calculated. The results show that the electric charges distributed on the sand surface have a significant effect on the attenuation of the electromagnetic wave, especially for a frequency lower than 40 GHz, and attenuation coefficients increase with the magnitude of charges carried by the dust particles (expressed by the charge-to-mass ratio in this paper). For the higher frequency electromagnetic wave, such as visible light, the effect of charges carried by sand particles on its attenuation is very little, which can be ignored.     

Storage time effect on free charge relaxation of amorphous poly (ethylene terephthalate)

Using thermally stimulated depolarization currents of PET-a electrets formed by the windowing polarization technique, the effect of the storage time previous to depolarization on the free charge relaxation, , has been studied. It was noted that the temperature at which the relaxation maximum appears increases with the storage time, whereas the intensity of the maximum decreases. This behaviour depends on both the polarization temperature and the polarizing field. It was also observed that there is a polarization temperature, the optimal polarization temperature, for which the relaxation maximum temperature does not depend on the polarizing field.     

Absorption of electromagnetic radiation by an inhomogeneous cylindrical particle

The cross section for the electromagnetic radiation absorption by an inhomogeneous cylindrical particle has been calculated for an arbitrary ratio of the dielectric core radius to the particle radius. The boundary conditions correspond to the diffuse reflection of electrons from the internal and external surfaces of the metal layer. Limiting cases are considered, and the results of analysis are discussed.     

Effect of magnetic relaxation times on electromagnetic pulseshielding

The penetration of an electromagnetic pulse (EMP) through a ferromagnetic conducting thin film is investigated for the case in which the magnetization of the material has a characteristic time delay τ. Both saturation and hysteresis effects of he magnetization are considered and the susceptibility is defined in the nonlinear region as dM/dh. It is found that the response time τ has a significant effect on the shielding factor with optimum shielding when τ is on the order of twice the rise time of the pulse     

The relaxation times of an STJ detector: Role of the proximity effect

The behavior of a superconducting tunnel junction detector (STJ) in the regime of low excitation is described, and the characteristic times of the dynamical response are discussed. The effect of a proximity layer in the STJ is analyzed in terms of the McMillan model. A set of phenomenological equations for the proximized STJ driven out of equilibrium is obtained, showing the importance of the role of the proximity effect in the dynamics of the device.