DC Arc Plasmatron Research Articles

Limiting Current of a Discharge from a Tubular-Cathode DC Arc Plasmatron

The published data indicating that the current toward the cathode insert of a plasmatron has a limiting value and that this limiting value is correlated with the diameter of the insert are discussed. It is assumed that this correlation is associated with the achievement of a critical value by the surface temperature of the insert at which the material evaporation rate grows sharply.

Estimation of the temporary service life of DC arc plasmatron cathode

The service life of the cathode of a DC arc plasmatron continuously working with tubular electrodes that operate in the air has been considered using the semi-phenomenological approach. The thermal emission, that ensures the necessary flow of electrons, and the evaporation of the cathode material, which determines its erosion, have been taken as the basic physical phenomena that constitute the workflow. The relationships that enable the estimation of the cathode’s operating time have been obtained using the known regularities of these phenomena and experimental data available in the literature. The resulting evaluations coincide satisfactorily with the endurance test results.

Plasmatron for ion-plasma surface of glass treatment at atmospheric pressure

Main mass of glass processing research is devoted to vacuum methods and to creation of non-penetrating coatings that are subject to physical and chemical impact. Therefore, the development of plasma devices that improve the efficiency of processing through the organization process at atmospheric pressure is an actual problem. The article suggests construction and studies operation modes of DC-arc plasmatron, which eliminates the need for powder coating material of a specific particle size, allows using as source material of introduction aqueous solutions of salts and increases the effective utilization of the implementation material at surface treatment of the glass. In view of the construction features of the developed plasmatron and its working conditions, as well as the weak dependence of the voltage of the electric arc on the Knudsen criterion (complex pd) a simplified equation of the current-voltage characteristics is proposed. The calculation of the current-voltage characteristics of the proposed dependence is in satisfactory agreement with the experimental data. The coefficient of efficiency of the developed plasmatron is 63 ... 80 %.

Production of titanium nitride nanopowder from titanium hydride based on synthesis in thermal plasma

The synthesis of TiN nanopowder from titanium hydride in thermal plasma generated in DC arc plasmatron is investigated experimentally. It is shown that a single-phase TiN nanopowder can be produced within a two-stage process consisting of plasma synthesis and separation of powdered product by means of sedimentation. The yield of nanopowder is up to 90%.

Study on Effect of Plasma Surface Treatments for Diamond Deposition by DC Arc Plasmatron

To improve the thermal conductivity and wear resistance of ceramic materials in the field of renewable energy technologies, diamond coating by plasma processing has been carried out in recent years. This study's goal is to improve diamond deposition on Al2O3 ceramic substrates by plasma surface treatments. Before diamond deposition was carried out in a vacuum, plasma surface treatments using Ar gas were conducted to improve conditions for deposition. We also conducted plasma processing for diamond deposition on Al2O3 ceramic substrates using a DC arc Plasmatron. The Al2O3 ceramic substrates with diamond film (5 x 15 mm2), were investigated by SEM (Scanning Electron Microscopy), AFM (Atomic Force Microscopy) and XRD (X-ray Diffractometer). Then, the C-H stretching of synthetic diamond films by FTIR (Fourier Transform Infrared Spectroscopy) was studied. We identified nanocrystalline diamond films on the Al2O3 ceramic substrates. The results showed us that the deposition rate of diamond films was 2.3 microm/h after plasma surface treatments. Comparing the above result with untreated ceramic substrates, the deposition rate improved with the surface roughness of the deposited diamond films.

Study on the Plasma Texturing for Increasing the Conversion Efficiency of a Solar Cell with a DC Arc Plasmatron

Study on the Plasma Texturing for Increasing the Conversion Efficiency of a Solar Cell with a DC Arc Plasmatron

Deposition of the ZnO transparent electrodes at atmospheric pressure using a DC Arc Plasmatron

Structure and electrical properties of ZnO films deposited by a DC Arc Plasmatron were studied. Films were deposited at atmospheric pressure on a cold substrate. Effect of annealing and plasma treatment was investigated. It was shown that in the as-deposited state the films have an amorphous structure and resistance of about 2 MΩ/cm. Annealing in hydrogen atmosphere at 550 °C improves the crystalline structure and decreases the resistivity of the films down to 5 Ω/cm. Also treatment of surface by hydrogen–argon plasma can be used for decreasing of the resistance of the ZnO films.

Deposition of ZnO Films on an Acryl Substrate Using a DC Arc Plasmatron

The DC arc plasmatron deposition of ZnO films on acryl substrates was demonstrated. The structure and the optical properties of the films were investigated. The XRD measurements revealed that the crystalline structure of the films depended on the deposition pressure. At atmospheric pressure, the deposited films were amorphous, and decreasing pressure led to the formation of polycrystalline films. The optical transmittance of the films was around 90 % in the visible region. We showed that minimal substrate heating could be achieved by varying the deposition parameters.

Effect of ion beam irradiation on the structure of ZnO films deposited by a dc arc plasmatron

The deposition of polycrystalline ZnO film on a cold substrate was performed by using a plasmatron in rough vacuum condition. Low energy oxygen ion beam generated by a cold cathode ion source was introduced during the deposition process. The change of film property on the ion beam energy was checked. It is shown that irradiation by 200 eV ions improves crystalline structure of the film. Increasing of ion beam energy up to 400 eV leads to the degradation of a crystalline structure and decreases the deposition rate.

Reduction of NO x in diesel engine emissions by using a plasmatron fuel reformer

An experimental study of diesel exhaust cleaning by means of the plasma chemical pretreatment of fuel is described. Some portion of the fuel was activated in an arc discharge and turned into hydrogen-rich synthesis gas. Plasma chemical reformation of fuel was carried out by using a DC arc plasmatron that was fabricated to increase the ability of gas activation. The yield of diesel fuel reformation reached about 80−100% when small quantities of fuel (flow rate up to ∼6 ml/min) were reformed. The synthesis gas, containing H2+CO, was supplied into the engine together with the rest of the fuel-air mixture, and the NOx content in its emissions reduced up to 23%.

The Effect of Component Gas on Diesel Reformation by a Plasmatron

We describe an experimental study of diesel-fuel reformation by a plasmatron and diesel-engine exhaust cleaning by means of plasma-chemical pretreatment of fuel. The plasma-chemical reformation of fuel was carried out by a dc arc plasmatron that was designed to increase gas-activation efficiency. Some portion of the fuel was processed by arc discharge and turned into a hydrogen-rich synthesis gas. By using Ar, He, H <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> , and N <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> as cathode protection gases, we discuss the plasma-forming gases and their effects on the reformation process. We analyze the volt-ampere characteristics of the arc discharge in the plasmatron for different gases. The yields of diesel-fuel reformation reached 80%-100% when small quantities of fuel (flow rate of up to about 6 mL/min) were reformed. This technology may be applied to diesel-engine exhaust cleaning by means of the plasma-chemical pretreatment of fuel.

The volt–ampere characteristics of a DC arc plasmatron with a distributed anode spot

A new DC plasmatron with a hot rod cathode and cold nozzle anode was proposed and tested at atmospheric pressure, generating nearly spectrally clean plasmas of air, air/diesel fuel mixture, oxygen, and CF 4. The arc Volt–Ampere characteristic (VAC) is an integral indicator reflecting the general behavior of all the arc parts, among which the most important are the by-electrode layers and positive column. The sensitivity of the VAC to the gas flow velocity in the technologic channel confirmed the external vortex nature of the anode arc spot, which does not hide inside the anode orifice, but exits it and interacts with the gas flow.