Liquid Conductivity Enhances Interfacial Stability in Plasma-Liquid Interactions

Plasma-liquid interactions are central to various emerging applications such as fusion reactors, water treatment, wound healing, cancer therapy, and nanomaterial synthesis. However, these interactions often trigger interfacial instabilities − splashes, bubbles, and oscillating deformations – that compromise plasma treatment efficiency. While cavity deformation has been visualized in prior work, the mechanism that governs interfacial stability remains unclear in several points. In this study, we focus on the conductivity of liquid, a parameter directly tied to ion concentration and known to alter electrohydrodynamic (EHD) forces. Since EHD forces drive interfacial flows under electric fields, we hypothesize that increasing conductivity suppresses interfacial instabilities. Experiments reveal that higher conductivity reduces cavity size and enhances stability under high-frequency pulsed jets. We quantify interfacial forces, measure flow fields, and estimate electron densities. These results show that tuning conductivity provides a robust means to stabilize the plasma-liquid interfaces.