Invisible structure of the cathode spot of a welding arc with a tungsten anode and a film cathode burning in an inert gas

A principal possibility is demonstrated to study the reverse side of the welding arc cathode spot with a high-speed camera. Photographs of the reverse side of the welding arc cathode spot were obtained for the first time. The discrete internal structure of the cathode spot is shown, and its individual structural elements were identified. A new object was observed in the burning of the welding arc, which was called a “free cathode spot.” Some parameters of the cathode spots (lifetime, the diameter of the front and reverse sides) were estimated. A new conceptual approach to the study of the nature of the cathode spot is presented.