Characterization of a twin-torch transferred dc arc

Abstract

The results of a twin-torch transferred dc arc study are presented. The arc system consists of two torches of opposite polarity, and a coupling zone of plasma jets located between them. The torch configuration increases the system reliability and efficiency during material plasma processing. The results of the study present data for the voltage-current characteristics, general behavior of the twin-torch arc, and spatial distribution of the plasma parameters. The plasma parameters have been measured using optical emission spectroscopy for a 200 A (20 k IV) dc arc at atmospheric pressure, with argon and nitrogen introduced as plasma-forming gases hzto the anode and the cathode units, respectively. The measurement technique used has allowed the determination of local electron density and temperature values in an inhomogeneous plasma volume having no axial symmetry. The data obtained illustrate the novel features of the twin-torch transferred dc arc for its applications in plasma processing.

Optical Emission Spectroscopy Measurements and Simulation of Radioelement Volatility During Radioactive Waste Treatment by Plasma

“…2). For optically thin low-temperature thermal plasmas with such parameter distributions, one can use the technique of local OES measurements developed elsewhere [16][17][18][19][20]. The technique is based on a steep (exponential) dependence of thermal plasma emissivity with temperature at constant pressure.…”

Modeling and Simulation of Chemical System Vaporization at High Temperature: Application to the Vitrification of Fly Ashes and Radioactive Wastes by Thermal Plasma

“…The reactor and the torches are cooled with water under pressure by two completely independent circuits. Argon is introduced at the tungsten cathode and the copper anode while oxygen, helium and hydrogen are injected through a water-cooled pipe [21]. To perform spectroscopic diagnostic above the molten surface, a water cooled stainless-steel crucible is placed under the coupling zone of the twin plasma torches.…”

Analysis of an Inhomogeneous Semitransparent Plasma by the Lines in the Emission Spectrum

“…The relations obtained permit local diagnostics of inhomogeneous, including axially asymmetric, plasma without using standard tomographic methods of the type of Abel inversion (in the case of axial symmetry). The methods developed for determining the plasma parameters have been used successfully to investigate electric arcs and plasma jets of technological purpose [5][6][7][8]. However, most of the results obtained pertain to optically transparent plasma and can only be used in the cases where the absorption in the spectral lines and its influence on their intensity and on the parameters of the profiles can be neglected.…”

“…Relative half-width ∆λ ⁄ ∆λ 0 of the spectral-line profiles with d/w = 0 (1-3) and 1.5 (4-6) versus the degree of reabsorption R of the plasma at T 0 = 0.7T and the degree of inhomogeneity α = 1 (1, 6), 2 (2), 5(3,5) and α = ∞ (4); ∆λ 0 is the line half-width in the transparent plasma radiation. change in the profile parameters caused by the self-absorption is small.…”

“…Earlier [5,28] it was shown that within the framework of the approximation under consideration at a comparatively low temperature and a low de- gree of ionization (kT 0 ⁄ E << 1, where k is the Boltzmann constant, E is the line excitation potential), to measure the transparent plasma temperature by the intensity ratio of two lines (a, b), one can use the formula…”