On the quantization of the electromagnetic field in conducting media

In this work we investigate the quantization of electromagnetic waves propagating through homogeneous conducting linear media with no charge density. We use Coulomb's gauge to reduce the problem to that of a time-dependent harmonic oscillator, which is described by the Caldirola–Kanai Hamiltonian. Furthermore, we obtain the corresponding exact wave functions with the help of quadratic invariants and of the dynamic invariant method. These wave functions are written in terms of a particular solution of the Milne–Pinney equation. We also construct coherent and squeezed states for the quantized electromagnetic waves and evaluate the quantum fluctuations in coordinates and momentum as well as the uncertainty product for each mode of the electromagnetic field.     

Joule-heating field phase-amplification in particulate-doped dielectrics

Doping dielectric materials with particulates for use in electronic device applications is wide-spread, particularly for energy-storage devices such as ultracapacitors and batteries. This work investigates the resulting distortion of the electrical fields in multiphase (particle and matrix) material systems. Of particular interest is to ascertain safe overall electrical loading conditions in order to avoid current overload in heterogeneous media. Specifically, it is important to determine the phase-wise Joule-type heating field, formed by the inner product of the current and electric fields. General estimates are developed, and two asymptotic cases are studied: (1) high-conductivity (“superconducting”) particles added to a lower relative-conductivity matrix and (2) low-conductivity (“insulator”) particles added to a higher relative-conductivity matrix. The expressions developed provide a relatively easy guide for the selection of dopants in dielectric material design.     

Recording the electromagnetic field excited in fracture of dielectrics and weakly conducting materials

Translated from Fiziko-Khimicheskaya Mekhanika Materialov, Vol. 23, No. 4, pp. 96–98, July–August, 1987.     

Heating characteristic of imperfect dielectrics in a traveling electromagnetic wave field

A new characteristic of a dielectric in an electromagnetic field, the rate of adiabatic heating of the boundary of a semiinfinite dielectric bulk under normal incidence by an electromagnetic wave, is proposed to describe the heating of dielectrics whose parameters are temperature dependent.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 37, No. 6, pp. 1101–1103, December, 1979.     

On the fast search algorithms for vector quantization encoding

One of the major difficulties arising in vector quantization (VQ) is high encoding time complexity. Based on the well‐known partial distance search (PDS) method and a special order of codewords in VQ codebook, two simple and efficient methods are introduced in fast full search vector quantization to reduce encoding time complexity. The exploitation of the “move‐to‐front” method, which may get a smaller distortion as early as possible, combined with the PDS algorithm, is shown to improve the encoding efficiency of the PDS method. Because of the feature of energy compaction in DCT domain, search in DCT domain codebook may be further speeded up. The experimental results show that our fast algorithms may significantly reduce search time of VQ encoding. © 2003 Wiley Periodicals, Inc. Int J Imaging Syst Technol 12, 204–210, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ima.10030     

On the nature of the Vorob’evs effect in pulse breakdown of solid dielectrics

The Vorob’evs effect consists in certain features of the discharge observed when a solid dielectric in contact with two rodlike electrodes is placed in a liquid dielectric medium and a voltage pulse with increasing front is applied to the electrodes. When the pulse front slope is small, the discharge develops in the liquid over the solid dielectric surface; whereas the discharge at a sufficiently large slope of the pulse front penetrates into the solid and produces its fracture with cleavage of the surface fragments. In order to explain this phenomenon, it is suggested that, at a sufficiently high voltage buildup rate, a displacement current that is related to the motion of the surface discharge plasma passes through a microprotrusion occurring on the electrode surface at the contact site and causes the electric explosion of this microprotrusion. The metal plasma jet generated as a result of this explosion penetrates into the solid dielectric and forms a discharge channel in depth of this material. The surface discharge plasma formed at a small slope of the voltage pulse front closes the electrode circuit, thus preventing the discharge penetration in depth of the solid.     

Disruption of the stationary state and electrical breakdown in amorphous dielectrics II. Ionic dielectrics

A phenomenological model is proposed for ionic dielectrics which describes the condition for disruption of the stationary state of conduction electrons emitted from localized sites in the high mobility band and accelerated up to the energy of avalanche ionization. It is found that the electric strength of amorphous ionic dielectrics decreases with increase in film thickness and temperature. The influence of the intensity of interaction of delocalized electrons with optical phonons in polar amorphous dielectrics, the character of the interconnection of an electron with a trap and the correlation between the states on electrical breakdown are investigated.     

Disruption of the stationary state and electrical breakdown in amorphous dielectrics I. Covalent dielectrics

In amorphous covalent dielectrics characterized by deep tails in the density of states, the problem of disruption of the stationary state of the system of delocalized electrons accelerated by an external field is solved by the deformed coordinate method. Analytical expressions for the dependence of the breakdown field on dielectric thickness and temperature are obtained. A comparison with experiment is in progress.     

Representations in elastic dielectrics

The method of associated matrices is employed to obtain Galerkin type representations for the equations of motion of linear elastic dielectrics. Fourier transforms are applied to the equations written in terms of stress function to construct matrices of fundamental solutions for the problems of concentrated body force, electric force and the charge density. The singular matrices and the reciprocity relation yield integral representations for the displacement vector, polarization vector, and the potential fields.     

Fabrication and characterization of directly-assembled ZnO nanowire field effect transistors with polymer gate dielectrics

We report the fabrication and electrical characterization of ZnO nanowire field effect transistors (FETs). Dielectrophoresis technique was used to directly align ZnO nanowires between lithographically prepatterned source and drain electrodes, and spin-coated polyvinylphenol (PVP) polymer thin layer was used as a gate dielectric layer in "top-gate" FET device configuration. The electrical characteristics of the top-gate ZnO nanowire FETs were found to be comparable to the conventional "bottom-gate" nanowire FETs with a SiO2 gate dielectric layer, suggesting the directly-assembled nanowire FET with a polymer gate dielectric layer is a useful device structure of nanowire FETs.     

On the possibility of electron-beam processing of dielectrics using a forevacuum plasma electron source

An insulated target was irradiated by an electron beam generated by a forevacuum plasma electron source operating in the pressure range of 5–15 Pa. Measurements of the target potential showed that plasma formed in the region of electron beam transport ensured the almost complete neutralization of charge accumulated on the target. This effect results in the possibility of direct electron-beam processing of nonconducting materials, including the melting and welding of ceramics.     

Energy storage in ceramic dielectrics

An evaluation has been made of the energy storage capabilities of ceramic dielectrics that were considered likely to provide high energy/volume efficiency on the basis of their expected permittivity-field characteristics. Data for fields up to 400 kV/cm are presented for a strontium titanate, and for a barium titanate ceramic. The materials were in thick-film form and bonded with a small amount of glass. At the maximum fields, energy storage in the barium titanate ceramic was close to that reported earlier for glass-bonded lead zirconate (approx. 2.0 J/cm³), but was about 30% lower in the strontium titanate material.     

Radiation pressure and the photon momentum in dielectrics

We review the magnitudes of the photon momenta in free space, derived by Maxwell and Einstein, and those in homogeneous, dispersionless and lossless dielectrics, associated with Abraham and Minkowski. These momenta determine the forces exerted by light beams on material objects, as measured in radiation pressure experiments. It is shown that conservation conditions for components of the electromagnetic energy–momentum tensors derived by Abraham and Minkowski, also by Einstein and Laub, are equivalent relations simply derived from Maxwell's equations. The challenge for theory is the reliable interpretation of experimental momentum transfers from light to matter, which requires extensions of the basic theory to include material dispersion and surface effects. The main experiments are reviewed, together with details of a Lorentz-force theory that accounts for them. It is shown that the Abraham kinetic momentum is associated with the overall motion of a dielectric sample, while the Minkowski canonical momentum applies to the motion of bodies embedded in the dielectric.     

Cluster structure of the near-electrode layer in liquid dielectrics

A method for determining the characteristics of charge clusters in low-conductivity liquids and an experimental setup for its realization are proposed. From the experimental results an inference about the molecular structure of the contact layer has been drawn. Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 73, No. 4, pp. 827–831, July–August, 2000.     

Inhomogeneous waves in transversely isotropic dielectrics

Summary The propagation of inhomogeneous transverse plane waves in a transversely isotropic dielectric solid is investigated within the theory of generalized piezo-thermo-elasticity. Geometrical restrictions on the real and imaginary parts of the wave vector are obtained as a consequence of the particular anisotropy of the solid. Dispersion relations for the most significant propagation modes are derived and discussed. Allowing for the inhomogeneity yields a generalization of previous results on piezo-thermo-elastic waves.     

Lattice defects in linear isotropic dielectrics

Using the concept of multipole forces, the problem of dislocations in a linear, isotropic, dielectric material is solved in a closed form. Solutions are also given using the distortional model. Both results are in agreement with each other. The former method has however the advantage to be applicable to all defects. Edge and screw dislocations are solved in details. It is shown that when polarization gradients are accounted for, the Green's function of linear dielectric materials can be determined analytically thus making it possible to solve and explain many phenomena not tractable with other models.