Electric arc in plasma flow of gas discharge with a liquid electrolyte

The properties of an electric arc ignited in a gas discharge plasma flow with a liquid electrolyte cathode are experimentally investigated. Aqueous solutions of sodium chloride with a specific electrical conductivity of 10-15 mS/cm were used as a liquid electrolyte. The distance between the anode and the liquid electrolyte cathode was set in the range of 5-60 mm, and the distance between the anode and the metal cathode was varied in the range of 2-30 mm. The current of gas discharge with a liquid electrolyte cathode was set in the range of 5-10 A, and the arc current varied in the range of 1-10 A. The conditions under which the arc burns with the formation of a contracted channel are revealed.

INCREASING THE ENERGY EFFICIENCY OF THERMOCATHODES OPERATION

The paper presents the results of experimental research on modifying the active area of cathode surfaces applied in the construction of electronic guns and increasing their operating efciency. The intensity of the thermo-electronic emission current is directly proportional to the area of the active surface of the cathodes used for this purpose. To change the micro-geometry of the metal cathode surface, the method of pulsed electric discharge machining (PEDM) was applied. As a result of the application of the discharge plasma on the surface of the cathodes, Taylor cones with heights ranging from 50 to 100 µm were extracted. The analysis of the obtained current-voltage characteristics allows us to compare the values of the saturation current intensities for unprocessed cathodes and those processed by the proposed technology. The increase of the active area of the cathodes with conical asperities causes the increase of the electronic thermoemission current by 10^4. A comparing to the cathodes whose active surfaces have not been processed by this method.

Investigation of Electrowinning of Mg from MgO Using a Liquid Metal Cathode in MgF2-CaF2-NaF or MgF2-LiF Molten Salt

A novel magnesium (Mg) production process utilizing an electrolytic method was investigated for the direct reduction of magnesium oxide (MgO). Electrolysis of MgO was carried out with an applied voltage of 3.0 V using a copper (Cu), silver (Ag), or tin (Sn) cathode and carbon (C) or platinum (Pt) anode in magnesium fluoride (MgF2)−calcium fluoride (CaF2)−sodium fluoride (NaF) at 1273 K or MgF2− lithium fluoride (LiF) at 1083−1093 K. After the electrolysis of MgO in MgF2−CaF2−NaF molten salt, Mg alloys such as Mg2Cu, Cu2Mg, or Mg2Sn phases were produced with current efficiencies of 75.8−85.6% when the concentration of Mg in Mg alloys was 9.1−14.6 mass%. In addition, when the electrolysis of MgO was conducted in MgF2–LiF molten salt, Mg alloys such as Mg2Cu or AgMg phase were produced with current efficiencies of 76.2−81.7% when the concentration of Mg in the Mg alloys was 12.5−13.2 mass%. In addition, to produce high-purity Mg metal from Mg alloys, vacuum distillation was conducted. When vacuum distillation was conducted at 1100−1400 K for a duration of 5 h, the concentration of Mg in the Mg alloys feed decreased from 30.2−34.1 mass% to 0.64−1.75 mass%, and Mg metal with a purity of 99.998−99.999% was obtained under certain conditions. Therefore, the molten salt electrolysis using liquid metal cathode (MSE-LMC) process developed here is feasible for the direct reduction of MgO using an effective and environmentally sound method.

Simulation of High-Voltage Ion Diode with Wire Cathode at Atmospheric Pressure of Nitrogen

Physic-topological simulation of a high-voltage coaxial ion diode with a wire metal cathode at atmospheric nitrogen pressure in the hydrodynamic drift-diffusion approximation is performed. The reactions of nitrogen ionization by electrons, attachment of electrons to nitrogen molecules with the formation of negative ions, recombination of charged particles with opposite signs of charge, secondary ion-electron emission of the cathode were taken into account. The distribution of potential and density (concentration) of charged particles in the interelectrode gap, the density of ionic and electron currents at the electrodes were calculated within the self-consistent problem with the following parameters: diameter of wire metal cathode 0.01-0.16 mm, diameter of tubular anode 6 or 20 cm, voltage 20-40 kV, gas temperature 300 or 600K. The influence of geometry, voltage and gas temperature on the discharge parameters has been determined. The obtained calculated data on the discharge current are consistent with the experiment. It is shown that two zones are formed in the discharge between the electrode gap – one is with a width of about 1 mm with a strong and rapidly changing electric field near the cathode and the second long zone with the drift of charged particles towards the anode with a smaller but constant field strength. This is a characteristic feature of negative corona discharges. In the cathode zone there is an intensive ionization of nitrogen with the generation of positive ions and electrons. In the second zone, the density of positive ions decreases sharply due to recombination and weak ionization. The reaction of attachment of electrons to nitrogen molecules begins almost near the cathode surface and continues throughout the cathode zone, in the drift zone the concentration of negative ions gradually decreases. Moreover, the role of electronic conductivity is greatly reduced as we approach the anode. Due to the low mobility of negative ions and, accordingly, the high electrical resistance of the drift zone, the voltage drop on this space part represents a significant portion of the discharge voltage (~1.5 kV on the cathode zone and 18.5 kV on the drift space, at the total voltage of 20 kV). The fact that the highest concentration of positive ions is formed near the cathode, and negative – along the entire interelectrode gap, it can be used, respectively, in the processes of ionic nitriding of wire cathode metal materials and for processing materials and biological substances (bacteria, viruses, fungi), sensitive to negative ions, at the location of the carriers of these substances near the anode. To implement the latter, it is advisable to modify the design of the external anode for efficient extraction of nitrogen ions into the environment. It is also advisable to continue research in the direction of increasing the energy efficiency of ion generation by determining the method of the maximum allowable reduction of the voltage drop on the space of drift of charged particles.

Rancangan Alat Elektroplating dan Eksperimen Pelapisan Berbahan CuSO4 Terhadap Ketebalan Lapisan

The electroplating method has the aim of producing a surface that has characteristics by the coating metal. The coating process requires a device that can place the ions from the coating material (anode) into the coated metal (cathode) through an electro-deposition process. Parameters such as temperature affect the electroplating process and greatly determine the coating result. The purpose of this study was to design the electroplating device, as well as to test the coating process using CuSO4 anode. The research method was carried out with an experimental approach through the manufacture of electroplating tools and coating testing of time variations of 20, 26, 32, 38, and 44 minutes and temperatures of 60, 65, 70, 75, and 80 oC. The results of the electroplating device design consist of frame components, plating and rinsing tubs, electrical systems, and cathode hanger. The coating results obtained the highest layer thickness 2.890 μm at a temperature of 80 oC for 40 minutes.

Highly selective CO2 conversion to methane or syngas tuned by CNTs@non-noble metal cathode in Zn-CO2 flow battery

Metal-CO2 batteries represent a potential new environmental protection technology, which can effectively reduce CO2 emissions while ensuring energy output. However, the design of active, selective, and cost-efficient electrocatalyst remains a...