The twin-electrode TIG coupling arc is a newly developed non-axisymmetric welding arc. The imaging method that consists of a high-speed camera with a narrow-band filter has been used to obtain monochromatic images of a coupling arc at atmospheric pressure. The spatial emission coefficients of the non-axisymmetric coupling arc are reconstructed by means of the Maldonado method. Under the assumption of local thermodynamic equilibrium, the temperature distribution of the coupling arc has been determined. The temperature distribution is similar to an ellipse, and the short axis of the ellipse is in the direction that the two electrodes are arranged along. The highest temperature area is in the middle of both electrodes. It indicates that there is a strong interaction within the coupling arc. The results show that the imaging method is an efficient way of characterizing the non-axisymmetric coupling arc.

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