Parameters of free-burning arc discharge plasma in air with silver-based electrodes

Abstract

We have used optical spectroscopy to study the radial temperature profiles for an electric arc plasma between silver electrodes and electrodes made from composite materials based on silver (Ag-CdO). We studied the structural changes in the working layers of the electrodes by metallography. We established that the parameters of the arc discharge plasma are determined by the condition of the electrode surface.Introduction. Wide application of composite materials in devices for the electrical engineering industry has stimulated interest in studying an arc discharge plasma burning between electrodes made of such materials. Optimization of various technological devices is impossible without knowing the parameters of the plasma for such a discharge.The electrical and thermophysical properties of silver and composites based on silver explain why they are so popular, in particular Ag-CdO composite materials with oxide content of 5-20 mass % are often used in electrical contacts for low-voltage switching devices.In this work, we have used emission spectroscopy methods to study the radial temperature distribution in an electric arc free-burning in air between electrodes made from silver or silver-based composite materials. Since a freeburning arc occurs when breaking the contacts in switching devices, we believe that the studied discharges can be a model for such arcs.The experiment. The arc was initiated in air between the flat end surfaces of uncooled, cylindrically shaped electrodes. The electrode diameter was 6 mm; the interelectrode gap was 6 mm, the discharge current was 3.5 A.Due to the spatial and temporal instability of the discharge, we used the method of one-pass tomographic recording of the spatial distribution of spectral line intensities [1]. Fast scanning of the spatial distributions of the radiation intensities was performed using a (B/W) Sony ILX526A (Japan) 3000 pixel CCD linear array. In combination with a spectral instrument, this allowed us to record the radial radiation distribution in the central cross section of the discharge of a nonsteady-state arc. The operation of the CCD linear array was controlled and synchronized with the discharge power supply using a personal computer (PC). An ISA interface was used to connect to the PC. In order to work with the Windows 9.x./NT/XP family of operating systems, we developed a software interface capable of collection, approximation, and statistical treatment of data, Abelian transformation, and calculation of the plasma temperature. The recording procedure is described in detail in [2]. Due to the instability of the discharge, we carried out statistical averaging of the recorded spatial distributions of the radiation characteristics. We also took into account the nonuniformity of the spectral sensitivity of the apparatus.In order to carry out the spectroscopic procedures for plasma diagnostics in electric arc discharges between composite silver-based electrodes, we need reliable information about the spectroscopic constants of the spectral lines for silver an...

Effect of Plasma Gas Type on the Operation Characteristics of a Three-Phase Plasma Reactor with Gliding Arc Discharge

“…This makes the arc difficult to control from the point of view of maintaining the required characteristics necessary for plasma processes. Free arc plasma is characterized by relatively low-quality technological and energy parameters [55], and the arc itself adversely affects the power grid. Low-temperature arcs generate a lot of electromagnetic interference, voltage sinks and surges, overvoltage, noise and harmonic distortion in the voltage and current [56].…”