High-voltage Glow Discharge Research Articles

Experimental investigation of the efficiency of a high-voltage glow discharge as a source of a beam of run-away electrons

To determine the energetic efficiency of the formation of the run-away electron beam in a highvoltage glow discharge, we measure the temperature of the electron beam generator. According to the measurements, the energetic efficiency (the part of the input discharge power carried away by the beam) was 50–70% at the generator supply voltage of 4.4 kV and it increased up to ~85% at ~8 kV. The measurements were performed for the discharge in helium with copper, steel, molybdenum, and lanthanum hexaboride cathodes.

Simulation of energetic efficiency of triode high voltage glow discharge electron sources with account of temperature of electrons and its mobility in anode plasma

The article proposes an iterative technique of calculation of energetic efficiency of triode high voltage glow discharge electron sources’, based on taking into account the influence of heating of anode plasma by the accelerated electrons of electron beam and by the slow secondary discharge electrons, reflected from the anode. The increase of temperature of anode plasma influences its’ volume, as well as the concentration and mobility of ions’ in it. Therefore, the proposed model allows obtaining the corrected values of discharge current and energetic efficiency of electron sources by taking into account the thermodynamic parameters of anode plasma. In addition, one of the advantages of proposed iterative calculation technique is that the model is closed and self-consistent, therefore, it does not demand use of approximated data about the thermodynamic parameters of discharge plasma from references.

Plasma immersion ion implantation (and deposition) inside metallic tubes of different dimensions and configurations

There is a strong need for developing methods to coat or implant ions inside metallic tubes for many practical contemporary applications, both for industry and science. Therefore, stainless steel tubes with practical diameters of 4, 11 and 16cm, but short lengths of 20cm, were internally treated by nitrogen plasma immersion ion implantation (PIII). Different configurations as tube with lid in one of the ends or both sides open were tested for better PIII performance, in the case of smallest diameter tube. Among these PIII tests in tubes, using the 4cm diameter one with a lid, it was possible to achieve tube temperatures of more than 700°C in 15min and maintain it during the whole treatment time (typically 2h). Samples made of different materials were placed at the interior of the tube, as the monitors for posterior analysis, and the tube was solely pulsed by high voltage pulser producing high voltage glow discharge and hollow cathode discharge both driven by a moderate power source. In this experiment, samples of SS 304, pure Ti, Ti6Al4V and Si were used for the tests of the above methods. Results on the analysis of the surface of these nitrogen PIII treated materials, as well as on their processing methods, are presented and discussed in the paper.

DC and AC Performance of Graphite Films Supercapacitors Prepared by Contact Glow Discharge Electrolysis

In the present work, we fabricate and characterize carbon graphite films by high-voltage cathodic and anodic contact glow discharge electrolysis (CGDE) for supercapacitor applications. Transmission electron microscopy revealed that the carbon films obtained by anodic CGDE, in which a carbon graphite is used as the positive electrode, are in the form of two-dimensional, relatively large lateral size sheets without major fractures or structural distortions. Whereas with the cathodic configuration, tiny and elongated flakes of graphite attached to larger sheets are obtained. We observed negative Raman wavenumber shifts of the G peak and the appearance of the T peak at ca. 1100 cm− 1, which are attributed to thermal-induced strains and structural damages in the graphite crystal lattice, as well as to some C-C sp3 bonds content. In addition to the aforementioned results and optical emission spectroscopy, it is proposed that both formation mechanisms by electrochemical exfoliation and material evaporation occur depending on the used polarization. All-solid-state symmetric supercapacitors using polyvinyl alcohol/H3PO4 as gel electrolyte were fabricated and tested under dc and ac frequencies. We found two different behaviors: at dc and close-to-dc, the material prepared with cathodic CGDE showed close-to-ideal behavior with higher capacitance at different charging/discharging rates, which makes it more suitable for energy storage applications, whereas at higher frequencies ( ⩾ 100 Hz), the material prepared with anodic CGDE performed better for ac filtering applications that has been verified using an inverting integrator circuit.

Industrial Electron-Beam Installation L-4 for Melting and Vacuum Refining of Metals and Alloys

Electron-beam melting is the most effective method of refining and degassing metals in vacuum. Equipment for its implementation is produced in Germany, USA, Ukraine, and other countries. The paper discusses the design features and process capabilities of an industrial electron-beam installation of new generation for melting and vacuum refining of metals and alloys with an intermediate vessel or a direct crystallizer developed at the ELTECHMACH Research and Manufacturing Company (Vinnitsa, Ukraine). A distinctive feature of the installation is the ability to melt highly reactive and refractory metals and materials with a high gas content through the use of high-voltage glow discharge guns that operate steadily in relatively low vacuum.

Simulation and approximation of dependence of the current of the high voltage glow discharge electron gun from the voltage on the coil of electromagnetic valve as the element of a gas-dynamic control system

Simulation and approximation of dependence of the current of the high voltage glow discharge electron gun from the voltage on the coil of electromagnetic valve as the element of a gas-dynamic control system

Оценка энергетической эффективности импульсных источников электронов высоковольтного тлеющего разряда с учетом электродных процессов и параметров анодной плазмы

Оценка энергетической эффективности импульсных источников электронов высоковольтного тлеющего разряда с учетом электродных процессов и параметров анодной плазмы

A scaling criterion for the parameters of open discharge in various gases

A simple mathematical model developed previously for the description of processes in electron beam generators based on high-voltage glow discharge with runaway electrons (open discharge) has been used to express the dependence of the discharge current on the applied voltage. The influence of the gas type on the character of discharge has been analyzed, and the obtained dependences are compared to experimental data.

Estimation of the current-voltage characteristic of an open discharge

The simplest mathematical model for describing the processes in the electron beam generators based on an open discharge (i.e., high-voltage glow discharge with electron runaway) is considered. On the basis of the model, the discharge current-voltage characteristic is found. The resultant dependences are compared with experimental results.

Influence of the magnetic field on DLC coatings grown by plasma immersion ion implantation and deposition in crossed fields

Because of the problem of film peeling, it is generally difficult to obtain thick and well adherent diamond-like carbon (DLC) coatings on metallic substrates with good tribological properties. In this work, we propose to apply a plasma immersion ion implantation and deposition (PIII&D) process in magnetic bottle configuration using high voltage glow discharge in order to deposit DLC films directly over 304 stainless steel (SS) alloy. In such configuration, two couples of coils wound outside the vacuum chamber are used to produce region of low magnetic field for plasma confinement (~60G at the center axis). DLC coatings are characterized by Raman spectroscopy, scanning electron microscopy (SEM) and also morphologically by means of atomic force microscopy (AFM). Tribological behavior is investigated using a pin-on-disk tribometer, and after that, the scars are evaluated by means of SEM and Wyko NT1100 optical profiler. PIII&D experiments in crossed fields have been demonstrated to be an effective system to synthesize DLC films with good adhesion, excellent resistance against wear as well as good dry lubricant surfaces.

Estimating of current rise time of glow discharge in triode electrode system in case of control pulsing

There are represented relations for approximate estimation of discharge current rise time in triode electrode systems of high-voltage glow discharge in case of applying of control pulses to auxiliary electrode. Theoretical transient analysis of high-voltage glow discharge is based on definition of the anode plasma volume and its ions concentration. Represented calculations show current rise time in real systems of high-voltage glow discharge is from 20 to 250 μs. Obtained results have great practical value for design of cathode-ray equipment.

Investigation of electron-optics characteristics of triode gas discharge electron gun with cold cathode

Results of experimental investigation of plasma boundary position which affect on geometry parameters of electron beam in triode high voltage glow discharge electron guns both in pulse and regular operation modes, are considered.Experimental installation which allows providing visual control of discharge gap of triode electron beam gun was used for investigations. For these purpose anode and driving electrode were made transparent. Rectangular impulses with different frequency and durability till tens of milliseconds were used in experiments.Provided investigations shown that with increasing of discharge current decreasing of dependence of anode plasma boundary position from energetic parameters of gun is observed. Therefore for maximal current providing control of gun operation without critical changing electron beam geometry parameters is possible.References 7, figures 3

Generating stationary electron beams by a forevacuum plasma source at pressures up to 100 Pa

It is shown that, as the gas pressure in a forevacuum plasma electron source increases, electric breakdown in the accelerating gap is caused by the reverse flow of ions from plasma that is generated by both the electron beam and high-voltage glow discharge (HGD). By modifying the electrode system geometry in the accelerating gap of the electron source, it is possible to provide for a two-to threefold decrease in the HGD current. This allows the upper pressure in the electron source to be increased up to about 100 Pa when air is used as the working gas and up to 160 Pa in the source filled with helium.

Ignition Features of Plasma-Beam Discharge in Gas-Discharge Electron Gun Operation

The current paper presents the results of experimental researches to determine the mode features of plasma-beam discharge (PBD) generation by an electron beam injected by a low-vacuum gasdischarge electron gun (LGEG) with the cold cathode and hollow anode on the basis of the high-voltage glow discharge and in the range of helium pressure of P ? 10 ÷ 130 Pa. The PBD boundaries and their dependences on parameters of an electron beam are found. The influence of PBD on parameters of low-vacuum gas-discharge electron gun is revealed. It causes an avalanche increase of electron beam current and burning of plasma-beam discharge in the whole space of the vacuum chamber volume and generation of electromagnetic radiation is revealed. Achieved results will be used for implementation of various vacuum technologies in the medium of reaction gas and generated electromagnetic radiation.

Analytical calculations of anode plasma position in high-voltage discharge range in case of auxiliary discharge firing

We consider the mathematical model of triode high-voltage glow discharge range in case of auxiliary discharge firing. On a basis of analysis of elementary processes of charged particles interaction in a discharge range we obtain analytical relation, which allows to obtain the anode plasma position with regard to the cathode. Obtained results can be used for analysis of analysis of energy balance in a discharge range and self-maintained electron-ion optics of high voltage glow discharge electron sources in case of electrical control of electron beam current.

Expansion of the working range of forevacuum plasma electron sources toward higher pressures

It is shown that the pressure in forevacuum plasma electron sources is limited from above by a current component that arises in the accelerating gap from a high-voltage glow discharge and dominates in the electron beam. The working pressure range of such electron sources can be expanded toward higher pressures by limiting the current of the high-voltage glow discharge in the accelerating gap.

Investigation of the throughput of the dosing device gas leak for gas discharge electron gun

Model of capacity of valve with conic rod, which is used for control of beam current of high voltage glow discharge electron guns, is considered. Because of complicity of valve details geometry, mathematical model of dozed item is improved by suitable choosing of empirical coefficients and its approximation. On the base of modeling and experimental data analyzing of dependence of valve exploitation characteristics from geometry parameters of dozed item is provided. Obtained results can be used for simulation of stability of operation of high voltage glow discharge electron guns inconsisting of technological equipment

Biased Atmospheric, Sub-Atmospheric, and Low-Pressure Air Plasmas for Material Surface Improvements

This paper deals with some important aspects of recent research related to atmospheric, sub-atmospheric (SA), and low-pressure plasmas. It calls attention to the definition of the pressure ranges in which they are divided to avoid misconceptions in the literature. Pulsed bias applied to elements inside the plasma can lead to important effects such as ion implantation, nitriding, sputtering, heating, and diffusion, which can result in some of the effective applications in surface engineering such as plasma immersion ion implantation (PI3), plasma nitriding, magnetron sputtering, and so on. Electric fields are essential for the production of different types of plasma, either ac, dc, or pulsed ones, as seen in RF, self-sustained, glow, and high-voltage glow discharges, for example. The interrelation between the bias pulse, mean-free path, and Paschen law is examined, seeking for further improvement of processing of the material surface being used in many modern technologies. Results on PI3 in the low and near SA pressures, as well as their applications in metals, are also discussed.

Investigation of the Electron-Optical Properties of High-Voltage Glow Discharge Triode Electrode Systems Taking into Account the Position and Shape of the Anode Plasma Boundary

Analyzing of anode plasma boundary form and position in triode high voltage glow discharge electrodes systems is provided. Methodic of analyzing is based on photographing of discharge gap and on using of up-date methods of computer image recognizing. Obtained results show the principle possibility and perspectives of using triode glow discharge electron guns in the novel electronbeam technologies

Gas discharge electron beam vaporizer for deposition nanostructured coatings

Possibilities of using of high voltage glow discharge electron guns for deposition of chemically complex coatings in controlled gas medium is considered. Arc discharge, lighted over the crucible with evaporated material, is used for ionizing of high-concentrated vapors. Dependences of additional discharge current from the electron beam power are analyzed. Microstructures of deposited films are investigated. Provided investigations show the high efficiency of using high voltage glow discharge electron guns for deposition of nanostructurized composite coatings