The Potential Field in and around a Gas Discharge, and Its Influence on the Discharge Mechanism

Abstract

In the first part of the paper, results on the spatial extension of cathode and anode fall regions in carbon arcs are reported. Potential-probe measurements reveal that the potential drop in front of either electrode is confined to less than one tenth of a millimeter. In the second part of the paper, the distortion of the potential field in and around any discharge, as caused by the non-uniform space charge distribution in the discharge, is discussed for the cases of a low current carbon arc and a negative point corona; for the latter case use was made of data by Loeb. The potential field distortions result in radial electric fields which, depending on their polarity, seem to hinder or support the radial expansion of the discharge. Potential-probe measurements in low and high current carbon arcs are in good agreement with this theoretical analysis and prove the transitional region between the distorted potential field in the arc and the undistorted potential field outside of the discharge to be a fairly thin one.