Spatially resolved temperature measurement in the carbon dioxide arc under different gas pressures.

Abstract

Carbon dioxide (CO2) is a promising alternative to sulfur hexafluoride for high-voltage circuit breaker applications. It is important to have a detailed understanding of CO2 arc properties. In this paper, radial temperature distribution of the free burning direct current arc in pure CO2 was investigated. Optical emission spectrometry was applied under different pressures (0.5atm, 1atm, and 1.5atm) and at different axial positions (1mm, 2mm, 3mm above the cathode). Assuming local thermodynamic equilibrium, the Fowler-Milne method was adopted for O I 715.67nm and O I 777.19nm in the periphery of the arc, and the single-line method was adopted for C II 657.81nm near the center of the arc. Radial temperature profiles obtained by these two methods were combined at the position where normal temperature was assigned. The results indicate that near the center of the arc, higher pressure would lead to lower temperature; as the distance from the cathode to the position measured increases, the maximum temperature in the arc center would decrease. In addition, the temperature would decrease more sharply toward the periphery if the central temperature of the arc is higher.