INVESTIGATION OF A CATHODE REGION OF AN ELECTRIC-ARC

Investigations of the near-cathode region of the atmospheric pressure, 200 A arc burning in pure argon have been performed using spectroscop ic techniques. Several slices at different distances from the cathode tip have been observed side-on. In order to perform diagnostic measure ments of the plasma, the profiles of the Ar I and Ar II lines have bee n recorded. Phenomena inexplicable in terms of the model based on assu mption of a local thermodynamic equilibrium state and constant pressur e in the plasma have been observed and are shown on an Olsen-Richter d iagram.