Experimental investigation of the anode region of a free-burning atmospheric-pressure inert-gas arc. II. Intermediate current regime—multiple anode constriction

This paper reports the experimental investigation of multiple anode constriction in atmospheric-pressure arcs in argon and xenon. The investigations were carried out in a free-burning arc with water-cooled electrodes. Results are presented from spectroscopic measurements of the electron temperature and density in the arc column and near the anode in various regimes of burning. Analysis of the experimental data leads to the conclusion that the constriction occurs because of the development of an overheating instability near the anode due to the disruption of the balance between Joule heating of the plasma and its cooling via the emission of radiation.