Experimental evaluation of anode surface cooling on self-organization pattern formation in atmospheric DC glows

Abstract

Plasma self-organization patterns have been experimentally observed on both liquid and metal anode surface in atmospheric pressure glows. However, the origin of the self-organized pattern formation is still poorly understood and is currently under study. Computational modeling of free burning arcs most recently by Trelles suggests that pattern formation is sensitive to anode cooling and thus the pattern formation may be a consequence of a thermally driven instability.1 In this present work, active anode surface cooling was implemented for both liquid and metal surfaces to study its effect on self-organization pattern formation. In particular, the power deposited into the anode surfaces was investigated as a function of discharge parameters (current and voltage) and anode work function. An effective anode fall voltage is inferred from the power deposition measurements, which allows for a local estimation of the reduced electric field in the region of the anode spots. Fast camera imaging along with emission spectroscopy is used to document changes in the character of the anode spot plasma with operating condition.