Megawatt low-temperature DC plasma generator with divergent channels of gas-discharge tract

We have developed and studied a new effective megawatt double-unit generator of low-temperature argon plasma, which belongs to the class of dc plasmatrons and comprises the cathode and anode units with divergent gas-discharge channels. The generator has an efficiency of about 80–85% and ensures a long working life at operating currents up to 4000 A.     

Experimental determination of the temperature dependence of steel thermal conductivity

High Temperature - A technique of determination of the thermal conductivity of structural materials in a wide range of temperatures has been developed and verified. A three-dimensional simulation...     

Supersonic plasmatron nozzle profiling with the real properties of high temperature working gas

The effects of real gases (excitation of vibrational degrees of freedom, dissociation and ionization) taken into account for supersonic nozzle profiling. The paper presents the method of the supersonic nozzle profiling for non-monotonic dependence of adiabatic index on temperature. The results of nozzle profile calculation for two sets of input parameters, based on independently determined specific heat for molecular nitrogen N₂ and products of its thermal decomposition in the temperature range of 260–10⁵ K and atmospheric pressure are presented. The experimental set-up based on proposed method of supersonic nozzle has been developed and manufactured. The gas velocity at different distances from the nozzle outlet has been measured. Results show the existence of the supersonic and transsonic flow regimes after the nozzle.     

Plasma hardening of ridges of railway wheelsets

Plasma surface strengthening plant and processing of the rail rolling stock wheel pairs are described here. Following on from starting the equipment design up to hardened wheel pairs' acceptance, accurate adherence of the process-dependent parameters at plasma treatment, and automated control ensure hardened surface structure and properties stability, as the final result it guarantees road safety.     

The Influence of a Flow of Low-Temperature Nitrogen Plasma on the Morphology,Electric Properties,and UV Photoconductivity of ZnO Films on Sapphire

Technical Physics Letters - We have studied the influence of a flow of high-enthalpy nitrogen plasma generated by a dc plasmatron on the morphology, electrical properties, and UV photoconductivity...     

Investigation of low-temperature plasma generator with divergent channel of the output electrode and some applications of this generator

A review is made of experimental and theoretical investigations of processes occurring in low-temperature plasma generators (LTPG) with divergent channel of the output electrode, and the possibilities of utilizing these generators in new plasma technologies are analyzed. Comparison is made of the characteristics of discharge (including the current-voltage characteristic) in a divergent channel and in a cylindrical channel of uniform cross section. The effect of divergent channel of the output electrode and of its expansion ratio on the pattern of physical processes in LTPGs of different designs is studied. Investigations are performed of the distribution of electric current and heat flux density along a channel with a segmented output electrode. The voltaic equivalents of heat fluxes to cathode and anode are determined. The process of “shunting” of discharge is investigated, which causes fluctuations of electric arc-burning voltage. The investigations involving an LTPG with divergent channel reveal that the voltage amplitude in the case of shunting decreases with increasing current strength and, at high currents of argon arc, does not exceed 1–2 V. Results are given of spectral and visual investigations of LTPG. It is demonstrated that, in an LTPG with divergent channel, the plasma temperature in the region of energy input at currents of 300 A and higher exceeds 30 000 K. The significant part is found which is played by vacuum ultraviolet radiation in the process of closing the arc to anode. The mechanisms of erosion of the tungsten cathode tip are investigated, which play an important part in increasing the cathode service life by way of recirculation of tungsten atoms because of their ionization in the discharge gap. Results are given of using an LTPG with divergent channel of the output electrode in plasma technologies of surface hardening, cutting, and hard-facing of metals. The technology of plasma hardening of wheel pairs, adopted by the RZhD (Russian Railroads) Joint-Stock Company, provides for increasing the service life of railroad wheels by a factor of 1.5–2.     

Plasma Heating of Periclase-Carbonaceous Refractory for Lining of Steel Ladles

Metallurgist - The paper presents the experimental results on plasma heating of fired periclase-carbonaceous refractory material. A high heating rate of more than 1000°C/h was achieved. The...