Dielectric Substance Research Articles

Spectral-domain analysis of microstrip transmissionline covered with lossy dielectric

Microstrip transmission lines show many properties which make them suitable as a medium for contact measurement of complex dielectric permittivity. Such a system could be based on determining the effective permittivity of a microstrip line covered by an unknown dielectric substance. To achieve this, an analysis of a microstrip transmission line covered with a lossy dielectric is presented which is based on the well known spectral domain Galerkin method. A comparison of the analysis with experimental measurements is presented, which shows that the theory is accurate for a range of material permittivities.

Modal propagation analysis of a waveguide with a regular pentagonal cross section with conducting and nonconducting boundaries

AbstractUsing the weak guidance approximation and Goell's point‐matching method, a numerical analysis has been made of a guide with a pentagonal cross section, which may find wide applications in integrated optic technology. Two cases have been dealt with, namely, (i) a pentagonal guide cladded with a conducting substance, and (ii) a pentagonal guide loaded with conducting substance on alternate surfaces, the remaining surfaces being made of a dielectric substance. © 1995 John Wiley & Sons. Inc.

Appearance of stable glow discharge in air, argon, oxygen and nitrogen at atmospheric pressure using a 50 Hz source

Unusual glow discharges in air, argon, oxygen and nitrogen at atmospheric pressure can be produced using a 50 Hz source. This technique is introduced on the basis of the idea of a lower dielectric breakdown voltage gas. The electrode system, which is composed of a fine metal wire mesh of specified radius and a dielectric substance, is very useful for plasma surface processes and for chemical reactions in the plasma bulk. The observations of the Lissajous figure of voltage-electric charges and of the current pulse shapes are proposed as a method of distinguishing between the atmospheric pressure glow plasma and the silent electric discharge.

Nonlinear Refractive Index of Organic Materials under High Pressure

High pressure measurements on the nonlinear refractive indices(n2) of 2-methyl-4-nitroaniline (MNA) are investigated. A Fabry-Perot interferometer(FP) constructed with a pair of diamond anvil (DA) culets coated with a dielectric substance is used. The n2 irradiated by 10 nsec laser light pulses increases with pressure increasing up to 3.3 GPa. Further measurements on n2 by using shorter than nsec laser light pulses are discussed.

Accelerated Motion of a Metal Ring by Discharges with a Dielectric Substance

After a teflon plate superimposed on top of a glass plate is rubbed with cloth, it is held several centimeters away from the glass plate and a metal ring is put on the glass plate. The metal ring then begins to rotate on the glass plate by intermittent discharges between the teflon plate and the ring surface. The mechanism of acceleration of the metal ring is found to be the ring receiving the driving power by the Coulomb force accompanying the intermittent discharges between the teflon plate and the ring surface. The acceleration of the metal ring is measured by taking photographs of the rolling state of the metal ring.

Macroscopic friction and dielectric relaxation

Dielectric relaxation is known to depend on whether the process is controlled by field strength or by charge density. The aim of this study is to give mechanical meaning to the constant field (or transversal) relaxation time tau and the constant charge (i.e. constant displacement or longitudinal) relaxation time theta . First, it is demonstrated that the formal difference between field and charge control disappears if the perturbation is periodic. Then tau is shown to be the relaxation time of the transient torque applied to the system by the change of the direction of the field. Similarly, theta is the relaxation time of the deformation force in the dielectric substance brought about by a sudden change of the external field. By this token, both relaxation times are recognized as quantities proportional to the reciprocal internal friction coefficients of the substance, tau being connected with rotation and theta with translation.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Evanescent Intensity Of A Focused Gaussian Light Beam Undergoing Total Internal Reflection In A Prism

We calculate the evanescent electric field and intensity profile of a circular Gaussian light beam when it is focused by a lens, enters a spatially finite prism, and is totally internally reflected at a planar interface of the prism and a dielectric substance. The electric field and intensity at the interface depend on the indices of refraction of the prism, the 1 /e 2 width, wavelength, and polarization of the incident beam, the focal length and exit pupil of the focusing lens, the distance from lens to prism, the shape and size of the prism, and the beam's angle of incidence. Our calculations show the evanescent intensity profile to be well approximated by a Gaussian shape for many practical realizations of the lens and prism optical apparatus. The 1/e 2 width of the profile appears to depend primarily on the beam's 1 /e 2 width, the ratio of the focal length of the lens to this width, and the incidence angle. The polarization of the evanescent electric field is approximately perpendicular to the incident plane of the beam center for an incident beam polarized in this direction. It is within the incidence plane, but rotates with time and position along the inter­ face, for an incident beam polarized in the incidence plane of the beam center. The penetration depth (into the dielectric) does not have a strong dependence on position within the illuminated area. Experimental measurement of the intensity profile in one optical geometry agrees well with our theoretical predictions.

Anisotropy of KDP crystals containing traces of impurities

The magnetic properties of KDP crystals were experimentally investigated by measuring the torsional rigidity of a high-quality mechanical oscillating system in a magnetic field. It is shown that real KDP crystals, grown in laboratory and factory conditions, specially purified or containing traces of impurities (not more than 10−3 mole %), exhibit magnetic anisotropy. A relation is found between the anisotropy of the magnetic susceptibility (Δχ) and the magnetic field. The magnetic fields where Δχ becomes constant (H ≥ 400 Oe) were determined. The values of Δχ at these fields for different KDP specimens did not exceed 3·10−8. The method can be used to determine the magnetic anisotropy of any dielectric substance.

Methode d'excitation du spectre Raman d'une couche mince utilisant un reseau a grand nombre de traits

The Raman spectrum of a dielectric substance deposited in a few microns thick film on a diffraction grating (aluminium coating), is obtained with a trapped laser beam inside the film. In order to assure the most efficient coupling, a single mode of propagation is excited in “reverse coupling”; the selection of groove spacing is discussed.

Thermodynamic Properties of Surface Layer of Classical Electrons

Thermodynamic properties of a two-dimensional system of classical electrons on the surface of a dielectric substance are investigated on the basis of an expansion with respect to the plasma parameter e=2π n e 4 / T 2 , where n denotes the surface number density. The correlation energy density E c and the pressure P are calculated exactly to the order of e: E c / n T =2[ P / n T -1]=(1/2) e [ln (2 e )-1+2γ], γ=0.5772··· .

Theoretical Study on Infrared Monochromatic Absorption Coefficient of Soot Particles

The infrared emission of soot particle could is theoretically investigated. The dispersion formula of electromagnetic wave of dielectric substance is applied. For the optical constants of soot in the visible region, the experimental data of the carbonaceous substance whose carbon content is equal to that of soot are adopted. For the conduction electron, the damping constant is calculated form the electric conductivity. For the bound electron, the data of graphite are used. Optical constants in the infrared region are obtained and, by substitution of these values into Mie theory, the theoretical values of monochromatic absorption coefficients of soot particles are calculated. By comparison of these with the results of the spectroscopic experiment, it is made clear that the present values are much better than the previous theoretical values. Moreover, the influence of the carbon content upon the absorption coefficients is examined numerically and its result is found to agree with the experiments.

Theoretical Study on Infrared Monochromatic Absorption Coefficient of Soot Particles

The infrared emission of soot particle could is theoretically investigated. The dispersion formula of electromagnetic wave of dielectric substance is applied. For the optical constants of soot in the visible region, the experimental data of the carbonaceous substance whose carbon content is equal to that of soot are adopted. For the conduction electron, the damping constant is calculated form the electric conductivity. For the bound electron, the data of graphite are used. Optical constants in the infrared region are obtained and, by substitution of these values into Mie theory, the theoretical values of monochromatic absorption coefficients of soot particles are calculated. By comparison of these with the results of the spectroscopic experiment, it is made clear that the present values are much better than the previous theoretical values. Moreover, the influence of the carbon content upon the absorption coefficients is examined numerically and its result is found to agree with the experiments.

Supplementary note to the thir­teenth series of experimental researches in electricity

The author describes, in this supplementary note, experiments made with the view of determining the specific inductive capacities of dielectrics, by means of an apparatus of the following form. Three circular brass plates were mounted, side by side, on insulated pillars; the middle one was fixed, but the two outer plates were moveable on slides, so that all three could be brought with their sides almost into contact, or separated to any required distance. Two gold leaves were suspended in a glass jar from insulated wires, connecting each of the leaves respectively with the adjacent outer plate. The amount of disturbance in the electric equilibrium of the outer plates pro­duced by interposing a plate of the dielectric substance to be tried, after charging the middle plate, was taken as a measure of the spe­cific inductive capacity of that dielectric. By varying the size and one another, new conditions are supplied for the more exact deter­mination of the relative inductive powers of dielectrics of every de­scription ; and by sufficiently reducing the dimensions of the instru­ment, it may be rendered applicable to comparatively small masses of dielectrics, such as crystals, and even diamonds. An instrument capable of such universal application the author proposes to desig­nate by the name of Differential Inductometer . Also read, a Letter addressed to P. M. Roget, M. D., Secretary to the Royal Society, by James Ivory, Esq., F. R. S., accompanying a paper on Astronomical Refractions. Communicated by Dr. Roget.