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A one-dimensional (1D) fluid model is developed to investigate the effect of multi-frequency excitation consisting of consecutive harmonics on the charge of a single dust grain in a weakly collisional capacitively coupled plasma discharge. The spatial distributions of the electron density, the electrons temperature, and the charged particle flux are obtained and analyzed under the effects of the number of harmonics. It is shown that the number of harmonics considerably affects the discharge properties and the sheath thickness. In order to analyze the charge of an injected dust particle under the effect of different operating parameters, the model takes into account the electron and ion currents, as well as the effect of collisions between ions and neutral atoms. The results showed that as the number of harmonics increases, the particle charge increases in the powered sheath region while it decreases in the grounded sheath due to the electrical asymmetry effect. However, the charge remains constant in the central region where the electron temperature is constant. The present study further shows that the gas pressure and the driving frequency affect the dust charge oppositely, where an increase in pressure leads to a decrease in the dust charge, especially in the sheath regions, while the particle charge negatively increases as the driving frequency increases for all excitation waveforms. [ABSTRACT FROM AUTHOR]

The possibilities of igniting a combustible mixture in a high-speed flow using a microwave streamer discharge are considered. The results of experimental studies of the streamer discharge structure at various pressures are presented. To quantitatively characterize the intensity of combustion of fuel ignited by a microwave discharge, pressure and temperature measurements are used in various sections of the jet in the discharge wake. The results obtained demonstrate the possibility of igniting a model combustible mixture when propane or its mixture with air is sup-plied to the discharge region. The main physical mechanisms responsible for heating the discharge plasma to the ignition temperature of the combustible mixture and their characteristic time scales are revealed. The change in the dimensions of the combustion zone with a decrease in the initial proportion of propane in the mixture is discussed. The minimum duration and minimum level of microwave radiation required to ignite a model combustible mixture under various conditions are determined. [ABSTRACT FROM AUTHOR]

In this paper we developed a model of the ICRF plasma flow in a geometry of the two following regions: a plasma torch (narrow area) and a chamber (broad area). We used the numerical model developed in the COMSOL-multiphysics software with the given parameters of outlet pressure p = 133 Pa, drive power W = 1.3 kW, drive frequency f = 1.76 MHz and gas flow G = 0–0.4 g/s. We obtained the spatial dependencies of the electron density, electron temperature, pressure in the chamber, gas velocity and performed the analysis of effects in the broadening area. As a result, we noticed some features, which include an anomalous increase of the electron density in the broadening area. [ABSTRACT FROM AUTHOR]

The results of an experimental study of the initiation, development and maintenance of a plasma surface discharge initiated by microwave (microwave) radiation of a gyrotron (75 GHz, 300 kW, 6 ms) in air under normal conditions on the surface of a quartz substrate with metal inclusions are presented. It is shown that the velocity of the propagation of the discharge ionization front reaches 40 m/s, which corresponds to the thermal conduction propagation mechanism. In this case, the maximum calculated gas temperature of the plasma reaches 5500 K, which leads to the sublimation of metal inclusions. For the first time, the plasma parameters of a surface microwave discharge on metal-dielectric targets, which have been used in various aeroplasma and plasma-chemical applications, are presented. [ABSTRACT FROM AUTHOR]

An analysis of the formation of a void in the PK3 setup in dusty plasma with 3.4-μm-diameter melamine–formaldehyde particles—in an RF discharge in argon at a pressure of 12–50 Pa under microgravity conditions at the ISS is presented. The uniform state of the plasma can only be obtained at a voltage close to the discharge extinction voltage. The application of a low-frequency voltage of 20–50 Hz stabilizes the state of the dusty plasma and shifts the void formation threshold towards higher RF voltages. It is shown that the formation of a void is associated with non-local ionization of the plasma at the center of the discharge by fast electrons, which are heated in the near-electrode layers. [ABSTRACT FROM AUTHOR]

The radiation spectra of the RF discharge plasma of dichlorodifluoromethane during copper etching are obtained and analyzed. It is shown that radiation of the RF discharge plasma is represented by atomic and molecular components and it is assumed that the dependences of the intensities of the lines and bands on the external discharge conditions are determined by the excitation of the emissive states on direct electron impact. Moreover, their behavior agrees with the character of the dependences of the etching rate under the same conditions. [ABSTRACT FROM AUTHOR]

Despite the progress made in the treatment of nephrolithiasis, the existing methods of renal calculi destruction are not ideal and have both advantages and disadvantages. Considering the process of high-frequency glow discharge formation on the surface of an electrode and in an electrolyte solution, we obtained the results on the destruction of renal calculi in vitro. It was shown that the destruction of kidney stones by glow discharge plasma was caused by several processes—the plasma induced effect of hydrated electrons and shock wave effect of the electrolyte stimulated by electrical breakdowns in the plasma. The plasma generation modes were configured by estimating the thickness of the vapor–gas layer in which the plasma burns. Thus, the average rate of contact destruction of renal calculi was measured depending on the plasma generator input power and time of plasma exposure. We conclude that the method of stone fragmentation by high-frequency electrolyte plasma is rather perspective and can be used in endoscopic urology for percutaneous and transurethral lithotripsy. [ABSTRACT FROM AUTHOR]

Results of optical and gas-dynamic investigations of the microwave discharge plasma under conditions of gas-jet synthesis of diamond are reported. The data are analyzed for determining the temperature and composition of the mixture in the discharge chamber for the purpose of further optimization of the method. The influence of the flow rate of the injected gas mixture on the macroparameters of the gas mixture flow at the exit of the discharge chamber is studied. The temperature and pressure measured in the discharge chamber are used for the numerical analysis of the mixture composition depending on the injected gas flow rate. It is demonstrated that the mixture composition at the exit of the discharge chamber correlates with the rate of diamond synthesis. [ABSTRACT FROM AUTHOR]

High-frequency discharge plasma in halogen-containing gases is widely used in micro- and nanoelectronic technology for cleaning and dry etching the surface of semiconductor wafers and IC functional layers. In this paper, we study the surface quality (based on roughness data) of a semiconductor after plasma-chemical etching in R-23 freon plasma. Freon R-23 is widely used in the technology of etching Si, Ge, and a number of other materials (GaAs, GaP, InP), providing technologically acceptable interaction rates, and also satisfying the anisotropy and selectivity requirements. Nevertheless, the quality control of the surface of IC layers remains an urgent task of modern submicron electronics. [ABSTRACT FROM AUTHOR]

In this paper, we show and discuss a set of cross sections for electron collisions with dimethyl ether (DME, C2H6O) obtained by the standard swarm analysis of experimental data for drift velocities and ionization coefficients measured in pure DME and its mixtures with Ar and Ne by E. Oettinger and coworkers. While the existing cross section set gave relatively good predictions for drift velocities, it proved necessary to modify the inelastic cross sections in order to achieve a better agreement with drift velocities in gas mixtures and a good agreement for the ionization coefficient. Furthermore, the derived set of cross sections was used to calculate the electron transport and rate coefficients under the influence of a constant electric field and crossed electric and magnetic DC and RF orthogonal configuration fields. The effect of the magnitude and frequency of the fields on electron transport was studied separately. Our work has resulted in a database of collision and transport data which can be used in modeling of both DC and RF discharges and plasma applications containing pure DME and its mixtures. [ABSTRACT FROM AUTHOR]

Some types of the slot input of high energy into cylindrical and rectangular cavities are considered. The energy input through slot waveguiding apertures located at the central circle of the cavity is selected and optimized. The standing wave ratio of the system is determined. The change in the electrical field energy in the cavity, when the position of the slot waveguide is shifted, is simulated. The optimum (best for processing with microwave discharge plasma) positions of the objects and waveguide slots as well as critical positions (choosing which can put the oscillator out of action) are shown. The increase in the field density between two metallic objects is calculated. The results demonstrating the inacceptable way of the slot input of energy for solving some types of problems related to processing of complex surfaces with the microwave discharge are obtained. [ABSTRACT FROM AUTHOR]

Chlorine-containing plasma and its mixtures with molecular and inert gases, as well as plasmas of complex polyatomic gases, such as freons, are often used to form the topology on the surface of semiconductors. This article examines the surface quality (based on the roughness data) of the semiconductor structure of GaAs after plasma-chemical etching in the plasma of mixtures of HCl/Ar, HCl/Cl2, and HCl/H2, as well as R-12 freon and its mixture with argon. Freon R-12 is often used for etching Si, Ge, and a number of other materials (GaAs, GaP, InP), providing technologically acceptable interaction rates, and also meets the requirements for anisotropy and selectivity. Also, mixtures of active gases with inert (He, Ar) gases have become widespread, which can act both as simply diluent gases and as sources of ions for the ion bombardment of the sample for the further ionic stimulation of the desorption of the interaction products, which improves the functional properties surface, with a slight decrease in the speed of interaction. Nevertheless, controlling the surface quality of samples remains an urgent task in modern electronics. [ABSTRACT FROM AUTHOR]

A microwave beam (wavelength 4 mm, power 150–300 kW) generates an ionization wave in air in the subthreshold field in the shape of a conglomerate of thread-like channels that moves toward the beam. The periphery of the beam refracts in the plasma of the non-self-sustained discharge in the UV halo of the thread-like discharges and self-focuses in the recombining plasma behind the front of the plasmoid that consists of thread-like channels. The self-focusing of the peripheral regions of the wave beam causes local bursts of ionization behind the front of the leading plasmoid. [ABSTRACT FROM AUTHOR]

A program to simulate gas-discharge kinetics with allowance for the temporal evolution of the electron-energy distribution function is developed on the example of microwave discharge in molecular deuterium with electron cyclotron resonance. The model includes the averaged heating effect of the microwave field at cyclotron resonance, elastic collisions of electrons with electrons and heavy discharge components, and inelastic excitation and transformation reactions. The program considers the temporal evolution of the electron distribution function within these processes, and an algorithm that changes the boundaries of the design range of the distribution function depending on its current values is developed for it. This makes it possible to consider the function variations over a wide energy range. The conditions determining the algorithm accuracy are developed, and the counting-error dynamics upon variation of the parameters of these conditions is given. The adequacy and reliability of the simulation results, which are estimated based on the values of the introduced errors and comparison with third-party models, are shown. [ABSTRACT FROM AUTHOR]

We consider the excitation and absorption of waves in a magnetoactive rf discharge plasma in the conditions when the generator frequency is lower than the electron cyclotron frequency. We consider the cases of unconfined and confined plasmas in the cylindrical geometry and different regimes of excitation of plasma waves with different dispersion relations and field polarizations. The power input to the plasma depends on the distribution of external-source currents initiating the discharge and on the density parameter characterizing the plasma density and transverse sizes of the system. In the case of a plasma cylinder with a free surface or a plasma cylinder in a large conducting casing, which is most interesting for applications, plasma contains only potential and nonpotential E-type oblique Langmuir waves as well as a strongly nonpotential surface wave. The latter wave is practically not excited by external currents flowing over the cylinder surface for real parameters of the system. For high values of the density parameter, the effective resistance of the plasma with inducting excitation of the discharge is predominant. For moderate and low values of this parameter, capacitive excitation of the wave by the current on the plasma cylinder surface is found to be most effective. [ABSTRACT FROM AUTHOR]

It is shown that microbial cells can be immobilized on polymer matrices modified via plasma treatment. On the example of microbial cells Azospirillum brasilense Sp 7, A. lipoferum Sp59b, and Escherichia coli XL-1, it was found that the immobilization efficiency of biological objects depends on the film processing time in plasma. Treatment of a polystyrene film in a high-frequency discharge plasma allowed a significant increase in the lifetime of microbial cells immobilized on its surface. It was shown that the optimal time for film processing in plasma was 30 s, the time to immobilize microbial cells was ~ 20 min, and bacteria remained viable for up to 6 months after immobilization. The use of matrices modified with plasma treatment as a carrier for immobilized the microbial cells to production biosensors is proposed. [ABSTRACT FROM AUTHOR]

In an inductively coupled high-frequency discharge plasma, SiCxNy:H films are obtained from a mixture of hexamethylcyclotrisilazane vapor and argon at substrate temperatures of 100 to 400°C and a discharge power of 200 W. The simplest plasma components (nitrogen, cyan, silicon atoms, CH free radicals, and C2 dimers) are determined. Some physicochemical properties of the films, including the growth rate, types of chemical bonds, refractive index, transparency interval, and contact angle, are studied. The synthesized films have a polymer-like structure. [ABSTRACT FROM AUTHOR]

The results of experimental studies of combustion of propane–air gaseous mixture when it was ignited by a microwave discharge have been described. The mixture with different propane content fills a sealed radio-transparent tube placed along the axis of a focused linearly polarized quasi-optical microwave beam at atmospheric pressure. Multi-point ignition of the mixture is carried out near one end of the tube by a pulsed microwave discharge with a surface-developed streamer structure. The growth of gas pressure in the tube as propane burned was recorded in the experiments. The microwave pulse energy being invested in high-temperature discharge plasma has been estimated in them. The minimum percentage of propane in the mixture at which the microwave discharge ignites it has been determined in experiments. The time dependence of the pressure increase in the tube as the propane burns determines the combustion process dynamics. [ABSTRACT FROM AUTHOR]

The formation dynamics of the parameters of a microwave discharge in air localized at electric field maxima created by a specially developed focusing system is investigated using numerical simulations within an extended hydrodynamic model. All main parameters of the microwave discharge plasma are determined. The results on neutral gas heating demonstrate good agreement with the earlier experimental results. [ABSTRACT FROM AUTHOR]

The structure and photocatalytic properties of polydisperse zinc oxide (ZnO) powder treated with a low-pressure radio-frequency (RF) plasma discharge were studied. The photocatalytic properties of ZnO before and after the treatment were studied with respect to photodegradation of organic impurities using decomposition of methyl orange in aqueous solution by UV light as an example. It was found that the photodegradation kinetics were described well by first-order equations. The photodegradation mechanisms of methyl orange over untreated and plasma-treated ZnO samples were different. It was shown that the effectiveness of the photodegradation expressed in terms of reaction constants increased by 20% after RF discharge-plasma treatment of the photocatalyst. [ABSTRACT FROM AUTHOR]

The formation of a jet of a nonequilibrium multiply charged ion plasma is studied in the inhomogeneous gas jet. It is shown that the geometrical divergence of the jet restricts the maximum ion charge state and results in the spatial localization of the discharge. Stationary solutions corresponding to such regimes are constructed. The model proposed can be used to optimize modern experiments on generation of hard UV radiation due to the line emission of multiply ionized atoms in a gas jet heated by high-power millimeter and submillimeter radiation. [ABSTRACT FROM AUTHOR]

Microwave discharges in liquids represent a new direction in plasma physics and chemistry. Results of experiments on the recovery of metals from a liquid residue after vacuum distillation of the hydroconversion product of vacuum tower bottoms by treating the residue with microwave discharge initiated in its bulk at atmospheric pressure are presented. It has been found for the first time that the concentrations of Al, Co, Cu, Fe, Mo, Ni, V, and Zn metals in a treelike structure deposited on a microwave antenna are 10-20 times their concentrations in the substrate. [ABSTRACT FROM AUTHOR]