Temperature Distributions of Gas Tungsten Arc Plasma by Spectroscopic Methods

An experimental study was performed examining the sources of temperature variability of free burning arcs by some spectroscopic measurements. In this paper, quantitative spectroscopic methods, shown as follows, were applied for temperature determination of pure argon or 90% argon -10% hydrogen gas tungsten arc. (1) Fowler-Milne method, (2) Method of relative intensity ratio of ArII to ArI line, (3) Method of relative intensity ratio of ArII to ArII line, (4) Method of relative intensity ratio of ArI to ArI line, and (5) Method of relative intensity ratio of Hβ to Hβ line. In method (3)(4) or (5), it was shown that a slight difference of data in measured spectra intensities or tansition probabilities caused remarked one of temperature. Temperature distribution by method (1) or (2), howevewr, was not remarkably affected by those differences. In pure argon arcs, it was concluded that temperature distributions measured by all methods (1), (2), (3) and (4) approximately coincided with each other. This conclusion led that the great variability of temperature data in argon arcs published previously was not necessarily valid. It was found in 90%Ar-10%H2 arcs that the temperature distributions by methods (2) and (3) were in good agreement, whereas those distributions were different from both distributions measured by ArI intensities and by HI intensities in methods (1), (4) and (5).