Instability of a water column modulated by electric field and atmospheric pressure plasma

The interfacial dynamics between atmospheric pressure plasma and water are highly complex, governed by electric field, plasma-induced forces, and surface tension. These effects strongly influence the generation and transport of reactive oxygen and nitrogen species (RONS), which are important for plasma–liquid applications. In this study, the plasma–water interface is created around a coaxial water column, which exhibits Plateau–Rayleigh instability driven by surface tension [1]. The breakup length, defined as the distance from the water tube exit to the first droplet formation, serves as a measure of the instability. With only the electric field, the water column destabilizes, enhancing bulging and necking, and thereby shortening the breakup length. This destabilization results from the competition between Maxwell stress and surface charge repulsion. However, when plasma is present, the jet exhibits enhanced stability—evidenced by the elongation of breakup length, likely due to modified electric field distribution, altered charge distributions, and RONS-induced modifications to surface tension. This work demonstrates how plasma-induced effects and electric fields modulate the breakup dynamics of a coaxial water column.