The effect of a ledge in outlet electrode on operation efficiency of the two-chamber plasmatorch

Electric and thermal characteristics of the two-chamber plasmatorch with a stepped outlet electrode were studied experimentally. Formulas for determination of arc voltage, plasmatorch efficiency, and length of a narrow part of the outlet electrode were derived. It is shown that such a plasmatorch is more efficient than the plasmatorch with a smooth outlet electrode.     

Ion penetration into an ‘unfriendly medium’ and the double layer capacitance of the interface between two immiscible electrolytes

We develop a theory of the double layer at electrolyte | electrolyte interfaces with account for the finite thickness of the interfacial region. This includes the distribution of ions between the two phases and smooth variation of dielectric properties across the interface. The theory offers simple laws for the dependence of the double layer capacitance on the nature of ions, ionic concentrations and potential, which are in line with experimental observations. The theory shows which parameters reflect the nature of ions and the structure of the interface, and how these parameters can be extracted from the capacitance data.     

Plasma electric furnace for modelling the treatment technology for associated petroleum gas

The AC plasma electric furnace with graphite electrodes was tested using methane as the modelling gas. Its advantage for production of hydrogen and fine soot was demonstrated. It was found that 1150–1200 °C of the reactor wall is enough for complete methane decomposition. It was shown that specific erosion of graphite electrodes is about 5·10⁻⁹ kg/C at the average current density of 32 A/cm². The work was financially supported by the State Contract No. 02.515.11.5010 (March 6, 2007).     

The influence of the microscopic structure of surfaces on the optical properties of metals

The review outlines the state-of-the-art in the field of studies on the optical properties of metal surfaces. The use of recent theory has been examined to explain the results obtained in certain individual experiments on the surface modulation spectroscopy, outer photoemission and the surface Raman effect. The dependence of the surface plasmon spectrum on the surface microscopic structure has been given special consideration. It has been shown how information about the electronic structure of a surface, and the effect of adsorption on this structure in particular, can be extracted from the optical measurement data.     

A model of electrowetting, reversed electrowetting, and contact angle saturation

While electrowetting has many applications, it is limited at large voltages by contact angle saturation, a phenomenon that is still not well understood. We propose a generalized approach for electrowetting that, among other results, can shed new light on contact angle saturation. The model assumes the existence of a minimum (with respect to the contact angle) in the electric energy and accounts for a quadratic voltage dependence ～U(2) in the low-voltage limit, compatible with the Young-Lippmann formula, and an ～U(-2) saturation at the high-voltage limit. Another prediction is the surprising possibility of a reversed electrowetting regime, in which the contact angle increases with applied voltage. By explicitly taking into account the effect of the counter-electrode, our model is shown to be applicable to several AC and DC experimental electrowetting-on-dielectric (EWOD) setups. Several features seen in experiments compare favorably with our results. Furthermore, the AC frequency dependence of EWOD agrees quantitatively with our predictions. Our numerical results are complemented with simple analytical expressions for the saturation angle in two practical limits.     

On the interactions of adatoms on metal surfaces

Pariwise interactions of the adatoms and ions adsorbed on metal surfaces has been investigated with the help of the pole approximation in integral equations of the Lippman-Swinger type. These interactions have been shown to depend mainly both on the type of the metal spectrum and on the electron structure of the adatoms. The theory developed in this paper gives a satisfactory explanation of several facts observed in experiments, especially the longrange oscillating interaction between adatoms.     

On the effect of microscopic roughness of the metal surface on the surface plasmon dispersion relation and photoemission

The effect of microscopic surface roughness on the opical characteristics of metal is considered. The field near the rough surface has been calculated on the basis of integral equations containing only smoothly varying field components. It appears that the influence of surface plasmons can cause, as a result of drastic enhancement of the field at the surface, an increase by several orders in such observed surface effects as photoemission and Raman scattering by adsorbed molecules. The results of calculation are compared with the experimental data obtained from the study of photoemission from silver with rough surface. Expressions have been derived for the dispersion relation for surface plasmons on a rough surface.     

Synthesis of silicon carbide nanopowders in a two-jet plasma-chemical reactor

Results of experimental studies on production of nanostructured silicon carbide powders in a plasma-chemical reactor based on a two-jet plasmatorch are presented. The conditions of SiC formation as a function of temperature and composition of the initial components are determined by thermodynamic calculations. Possibility of silicon carbide synthesis with the size of particles of 5?20 nm is shown experimentally.