Multi-rod Electrodes Research Articles

КАРУСЕЛЬНАЯ УСТАНОВКА ДЛЯ РЕСУРСНЫХ ИСПЫТАНИЙ НА АБРАЗИВНЫЙ ИЗНОС

When developing new methods to make hardening coatings on the cutting tool surfaces of tilling machines, the main characteristic parameter determining the ability to serve for a long time, resisting external environmental influences and mechanical wear, is wear resistance. At the same time, this parameter should be determined before life tests in the field. Various stands and installations are available for this purpose. Each of them is characterized by their own advantages and disadvantages. Therefore, based on the specific production conditions, new devices are being developed. In this paper, a rotary-table installation of a specific design is developed for life tests of abrasive wear of various parts. A patent is obtained for it. The differences of this installation from existing analogues are the following: 1 – the pressure of the abrasive material layer on the test sample is regulated by deepening the sample into the abrasive medium; 2 - the test sample is under constant influence of the abrasive material by filling it with the required amount of abrasive materials; 3 – higher efficiency of the installation. This is achieved due to lower power consumption in the absence of friction forces between the sample bracket and the abrasive material. Comparative life tests were carried out for two harrow teeth, the original tooth and the hardened one. The harrow teeth were tested on a simplified model of a developed installation. An experimental inverter vibration control unit of Kazan Federal University was used for treatment. Hardening was performed with a multi-rod electrode at an arc current of 60A. The frequency of the electrode vibration is 100 Hz. Tests show that the service life of hardened harrow teeth when treated by a vibrating arc with a multi-rod electrode is about 5-6 times higher than the service life of factory harrow teeth.

Increasing of service life of harrow tooth of soil tillage machines treated by vibro-arc with multirod electrode

Metallographic studies of treated samples of tooth of soil tillage machines by vibro-arc with multirod electrode are carried out, their strength properties and microstructure of deposited layer and heat-affected zone are determined. The use of a multirod electrode during vibro-arc treatment allowed simultaneous introduction of elements of various refractory metal into the surface layer of the part. It is shown that vibro-arc treatment of surfaces with the use of multi-rod electrodes of various refractory and carbon materials increases the hardness of the surface layer more than 5 times.

Two dimensional simulations of triode VHF SiH4 plasma

Two-dimensional simulations of a triode VHF SiH4 plasma (60 MHz) were performed using a fluid model, where the plasma was realized using multirod electrodes. Higher-order silanes that are responsible for the quality of amorphous silicon were included in the simulations. A typical VHF plasma with an electron density higher than 1016 m−3 and an electron temperature lower than 3 eV was predicted between discharge electrodes while the electron density near the substrate was very low. The SiH3 density was fairly uniform between discharge electrodes and did not decrease rapidly near the substrate, suggesting a high-speed deposition. Higher-order molecules and radicals that play an important role in dust formation had similar spatial profiles and their densities were five to 6 orders of magnitude lower than the SiH3 density. We discussed the effect of the rate constant of reaction, SiH3 + SiH3 → SiH2 + SiH4, on the SiH3 density.

Arc development of triggered vacuum switch with multi-rod electrode system

Triggered vacuum switch (TVS) is one of the important switch apparatuses in the high pulsed power system, which takes the vacuum as insulation and arc-extinguishing medium of main gap. The conduction of TVS is the arcing process of vacuum arc in practice. So, it is meaningful to research on the vacuum arc characteristics for the high current application of TVS. A six-gap rod electrode system is studied in this paper. It is made up of 3 pairs of rod electrodes, i.e., spatially interleaved rods of opposite polarity on a ring. The arc development under different high currents is tested and discussed, based on the electrical characteristics of the vacuum arc voltage and arc resistance. The variety of arc voltage shows the parallel arcing and the transfer process in the multi-channel, which is benefit to maintain the diffusion of vacuum arc. A TVS sample based on multi-rod electrode has carried high current of 225 kA in peak and charge transfer of 45 C in a pulse.

Optimization of a Triggered Vacuum Switch With Multirod Electrodes System

The breakdown and triggering characteristics of triggered vacuum switch (TVS) are very important features, and they affect the operation reliability of TVS. Both of them mainly depend on the electrode material, electrode shape, gap distance, and surface condition. For an optimized electrode's geometry, finite-element method electrostatic field simulations were conducted to evaluate the effect of geometric parameters on the electrostatic field strength and distribution. The distribution of electrostatic field of the TVS with multirod system (MTVS) is calculated by the finite method. The simulation results show that the geometric enhancement factor (GEF) is decreased with the increase of the fillet radius of the edge of the rod. In case of the fillet radius for the side face of rod 3 mm and the fillet radius of the top face of the rod is 5 mm, the GEF is decrease to a minimum value of 3. The breakdown voltage of MTVS was measured by the high-voltage direct current generator after switch currents with amplitude of 63 kA and width of 13 ms with the interval time of 10–15 min. The influences of electrode materials and operation times on the breakdown voltage and trigger characteristics are also studied. The experimental results show that the breakdown voltage of the optimized MTVS is higher than that of the non-optimized MTVS. The breakdown voltage of CuCr30 is higher than that of oxygen-free copper. In addition to, the trigger characteristics of MTVS are influenced mainly by the electrode materials, the fillet radius of electrode has a little effect on the triggering characteristics of MTVS.

VHF SiH4/H2 plasma characteristics with negative ions

A VHF SiH4/H2 plasma was produced using a multi rod electrode and the plasma parameters were measured using a heated Langmuir probe, where the frequency of the power source was 80MHz. The Langmuir probe characteristics indicated that when the concentration of SiH4/H2 is increased, negative ions appear and at the same time the electron temperature increases.

大电流下多棒极型真空触发开关电弧特性

大电流下多棒极型真空触发开关电弧特性

Characteristics of SiH4/H2 VHF plasma produced by short gap discharge

A SiH4/H2 VHF plasma was produced with the multi rod electrode and the fundamental plasma parameters were examined as a function of pressure and power, where the frequency of the power source was 60MHz. It was found that the ion saturation current takes a peak at a certain power as well as pressure. These results were discussed from the point of view of electron trapping effect in VHF electric fields. In addition, anomalous reduction of the sheath potential was observed.

Control of large area VHF plasma produced at high pressure

The control of very high frequency (VHF) discharge plasma at high pressures was attempted by loading a variable capacitor to the end of the multi rod electrode with which VHF plasma (frequency 60 MHz) was produced. It was found that the discharge region is controlled with the variable capacitor and VHF plasma uniform over 1 m is produced at high pressures.

Large area SiH4/H2 VHF plasma produced at high pressure using multi-rod electrode

A VHF SiH4/H2 plasma was produced using a multi-rod electrode of 1200 mm×115 mm and the characteristics of VHF plasma at high pressure were measured with a heated Langmuir probe, where the frequency of VHF power source was 60 MHz and the power was up to 450 W. The pressure was ranged from 1 Torr to 3 Torr. When the pressure was increased, the ion saturation current density decreased independent of the concentration ratio of SiH4/H2 and the electron temperature tended to increase at high pressures. Furthermore, when the VHF power was increased, the wall potential decreased at high pressures.

Characteristics of VHF H2 Plasma Produced at High Pressure

AbstractA VHF H2 plasma was produced with the multi rod electrode at high pressure and the plasma parameters were measured as a function of pressure for different VHF powers at 60 MHz. It was found that when the pressure is increased, the ion saturation current peaks at certain pressure and finally decreases at high pressures, while the electron temperature is around 10 eV. The wall potential at high pressure was lower than the values estimated from the electron temperature using the probe theory. Furthermore, the anomalous reduction of the electron saturation current was observed. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Large Area SiH4/H2 VHF Plasma Produced with Multi-Rod Electrode

A SiH4/H2 VHF plasma with a frequency of 60 MHz was produced with a multi-rod electrode of 1 200 × 114 mm2 at high pressure. The plasma parameters were measured as a function of pressure and concentration of SiH4 to H2 with a tiny heated Langmuir probe. When the pressure was increased, the plasma density decreased independent of the concentration of SiH4 to H2, while the electron temperature increased to about 11 eV at 3 Torr. The wall potential defined as the potential difference between the plasma potential and the floating potential was anomalously small at high pressure, suggesting very low ion bombardment. Furthermore, Langmuir probe characteristics indicated that there exist much negative ions.

Corpuscular diagnostics of deuterium-plasma streams from RPI-IBIS discharges

The paper reports on experimental studies of pulsed plasma-ion streams generated by the RPI-IBIS facility equipped with coaxial multi-rod electrodes and operated at about 30 kV, with the pulsed injection of pure deuterium. Ion measurements were performed at time-delays τ (between the gas-valve triggering and a HV pulse) equal to 170 µs (slow mode) and 130 µs (medium mode). To determine mass-and energy-spectra of ions the use was made of a Thomson-type spectrometer. An influence of the initial gas conditions (determined by τ) on the energy spectra of deuterium-ions was demonstrated. To study the spatial structure of plasma-ion streams the use was made of an ion-pinhole camera equipped with PM-355 nuclear-track detectors and placed on the discharge axis. The application of Al-filters enabled to record deuterons of highest energy and to identify sources of their emission. The measurements confirmed the strong influence of the initial gas conditions on the energy distribution of the emitted plasma-ion streams and their spatial structure. The obtained results are of importance for basic plasma physics and for application-oriented research, e.g. modifications of different materials.

Anode mode of vacuum arc in a multirod electrode system

The effect of the plasma of a high-current vacuum arc on the anode rods in a rod electrode system, which leads to the melting of the surface of copper anode rods and to the formation of droplets of the electrode material, is investigated. High-speed photography is used to register the formation of anode spots, and the sizes of the spots are determined at discharge currents from 30 to 100 kA. A one-dimensional nonstationary model of the melting of the anode and of the formation of droplets in the anode spot of a vacuum arc is proposed. The model is in satisfactory agreement with the results of observation of traces of melting on the anodes of used dischargers in a rod electrode system and with high-speed photographs of glow of the discharge plasma and spots on electrodes in a model of the rod electrode system.

Correlation of x-ray and neutron emissions from an ion implosion system

The paper presents the results of space- and time-resolved studies of X-rays and neutrons emitted by the SOWA-150A ion-impulsion facility equipped with a coaxial set multi-rod electrodes. Proportionality and correlation of neutron and hard X-ray pulses favour the hypothesis of a beam-target mechanism of the neutron production.