# An Investigation into the Behavior of Cathode and Anode Spots in a Welding Discharge
## 5 Conclusions  
1. Using optical and high-speed camera methods, we studied in situ the optical properties of the arc spot on various surfaces of the cathode in a welding arc. We established a strong influence of the cathode anode surface on the discharge characteristics.
2. The display of anode spots in a high-resolution welding arc is a first. The mode of the anode spot in the welding arc is a high-current mode, when a more pronounced cylindrical arc column appears in the interelectrode gap while one cathode spot is covered by the cathode. At the anode, one large or (less often) several small, very bright round spots are formed in the center of the molten bath. We propose a technique for studying anode and cathode spots using an optical and high-speed camera.
3. The reference point mode differs from the vacuum arc by primarily filling the interelectrode gap with a sufficiently bright diffuse glow. However, unlike the diffuse arc mode, where the molten metal bath, which is the anode, does not glow, in the lower point mode, small, bright anode spots appear on the surface of the molten bath (anode) along the periphery of the molten bath. There may be several such spots. The heating spot designates these spots as the welding arc's reference points. The reference points are characterized as small luminous spots usually associated with the surface of the nonmolten metal and the melting of the anode. The appearance of the anode flares along the binding boundary of the reference points towards the cathode.
4. We show the dependence of the number of anode and cathode spots on the current strength and arc length. On an oxidized surface, the movement of cathode and anode spots is more stable than on a clean steel surface. The presence of oxide on the cathode surface leads to a change in microexplosive processes, which increases the stability of the spot plasma.
5. An experimental technique for studying the reverse side of the cathode spot is described, and the results of visualization are presented. We obtained experimental dependences of the cathode spot's average lifetime on the film thickness for various film cathode materials when studying from the reverse side. We experimentally determined the number of cathode spots fixed on the reverse side of the exposure period. We compared the geometric dimensions of the cathode spot, obtained using classical methods, with the proposed method.  
Conceptualization, A.I.K. and A.E.B.; methodology, V.V.K.; validation, V.V.R.; formal analysis, A.G.B.; investigation, V.V.R.; data curation, V.V.K. and Y.I.K.; writing--original draft preparation, A.E.B. and A.I.K.; writing--review and editing, Y.I.K., A.G.B., and V.V.K.; supervision, A.I.K. and Y.I.K.; project administration, A.I.K. and Y.I.K.; funding acquisition, A.I.K., V.V.R., and A.G.B. All authors have read and agreed to the published version of the manuscript.  
The research was funded by the state assignment of Ministry of Science and Higher Education of the Russian Federation (theme \(N\) 123102000012-2 \"Comprehensive study of aerodynamic characteristics of plasma systems of thermochemical fuel preparation\", agreement No 075-03-2023-028/1 of 5 October 2023).  
Not applicable.  
The data presented in this study are available from the corresponding authors upon reasonable request.  
The authors declare no conflicts of interest.