Abstract
In the present paper, the mechanism of mixing of metal vapor in arc plasma is discussed though the dynamic observation of spectra of helium, iron, chromium and manganese during stationary TIG welding of stainless steel and pure metals. Radiation from the arc is sent to a monochromator through optical lens and spectroscopic images are captured with 500 fps by a high-speed digital video-camera. Spectra of metal elements exist locally in the arc plasma due to dependence of plasma temperature and also intensive region of each metal spectrum depends on kinds of metal elements. The most part of metal vapor produced from the weld pool surface are carried on the cathode jet and then are swept away towards surroundings of the arc. However, if the driving force like diffusion in plasma is large, some metal elements can get across the cathode jet and then can be carried on the circulation flow towards tungsten electrode. Therefore, a part of metal vapor can be carried on this circulation flow towards tungsten electrode and then metal vapor can exist in the arc plasma.
