Characterization of Capillary Wave Coupled with Self-organized Pattern on a Liquid Anode of 1 atm DC Glow Discharge*

The self-organized anode pattern of a 1 atm DC glow discharge over liquid is a fascinating and perplexing phenomenon. Understanding its fundamental mechanism is challenging due to the limited diagnostics and the coupling with the plasma-liquid interface. Interestingly, complex capillary waves on the liquid are also incorporated in the self-organization since its topography shares the same pattern as the plasma attachment.

In this work, the 1 atm DC discharge-stimulating capillary wave on liquid is characterized by a background oriented Schlieren method. The three-dimensional wave field is also measured and analyzed temporally by a cross-correlation algorithm. The observed capillary wave is not only driven by the electrostatic pressure but also surface tension and therefore exhibits more fine features than anode pattern while its basic structure corresponds to the self-organized plasma attachment. In addition, a standing wave boundary outreach far from the plasma attachment and changes with liquid properties. This implies the importance of heat transfer and charge transport in the dynamics. The spatial and temporal couplings between the self-organized pattern and capillary wave reveal a non-trivial aspect of the plasma-liquid interface and provide additional insights into self-organization.