Observations of electric arc cathode region

Abstract

CCD camera images of the near-cathode region of an electric arc, working at atmospheric pressure in argon, permitted observation of some interesting phenomena that take place in this region, e.g. a `dark zone' in the cathode sheath region, low-frequency (f<0.1 Hz) fluctuations of discharge parameters and emitted light, the existence of several hot spots on the cathode surface, different kinds of movements of the arc spot on the cathode surface, and modification of the cathode surface structure.