Experimental study of the stability of the interface between a liquid electrolyte and the glow discharge plasma

The stability of the interface between a liquid electrolyte and the plasma of a contracted low-pressure dc glow discharge in air is investigated by means of digital photography. Water solutions of potassium permanganate and copper sulfate were used as electrolytes. It is found that, in the case of potassium permanganate, the instability of the interface leads to ejection of the electrolyte into the plasma and extinction of the discharge. Discharge modes with different types of quasi-steady interface are observed for copper sulfate at different values of the discharge current: a smooth interface, a solitary wave perturbation, regular ripples, and a churning foamed turbulent mixing zone.