A Comparison of the Experimentally Measured and Theoretically Predicted Temperature Profiles for an Argon Plasma Jet Dis
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A COMPARISON OF THE EXPERIMENTALLY MEASURED AND THEORETICALLY PREDICTED TEMPERATURE PROFILES FOR AN ARGON PLASMA JET DISCHARGING INTO A NITROGEN ENVIRONMENT A.H. Dilawari, J. Szekely, R. Westhoff Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, MA. 02139 B. A. Detering and C.B. Shaw Jr. Idaho National Materials Technology Engineering Laboratory, Idaho Falls, ID. 83415-2210 ABSTRACT Experimental measurements and computed results are reported, describing the behavior of a non-transferred arc plasma torch operating in a laminar mode, discharging into a nitrogen environment. The experimental measurements of the temperature fields in the vicinity of the torch exit, obtained using emission spectroscopy, were compared with theoretical predictions. The calculations were based on the solution of the axi-symmetric heat, mass, momentum, and species balance equations. The theoretical predictions were found to be in excellent agreement with measurement, with the error usually being in the 5-10% range and the maximum error being about 15%. 1. INTRODUCTION In recent years there has been a growing interest in the quantitative representation of plasma systems and this effort is well documented( 1 d 4 ). The work described in this paper is part of an ongoing effort aimed at the development of a comprehensive understanding of transport phenomena in nontransferred arc systems, through a critical comparison of experimental measurements and theoretical predictions - a joint effort by researchers at the Idaho National Engineering Laboratory and the Massachusetts Institute of Technology. In a previous paper we described a successful modelling/experimental effort in which the behavior of a laminar argon plasma jet, discharging into an argon environment was examined. In the present paper we shall report on an investigation of a slightly more complex system, namely the discharge of an argon plasma into a nitrogen environment. The obvious complicating factor is provided by the intermixing of the two gases, having dissimilar dissociation properties. 2. EXPERIMENTAL WORK The experimental apparatus consisted of a non-transferred arc plasma torch (Figure 1) and an atmosphere control chamber (Figure 2). The torch used a 9.5 mm diameter cone-shaped, thoriated tungsten cathode which was mounted in a watercooled copper support. The anode was a water cooled copper cylinder with an inside diameter of 12.7 mm and an overall length of 29 mm. The body of the plasma torch (76 mm diameter) protruded into the atmosphere control chamber as shown in Figure 2. The chamber was approximately a cube with inside dimensions of 0.5 m, which was continuously purged from several locations. The total purge flow rate to Mat. Res. Soc. Symp. Proc. Vol. 190. @1991 Materials Research Society
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