Stabilization of liquid instabilities with ionized gas jets

Area of Science:

• Fluid Dynamics
• Plasma Physics
• Surface Science

Background:

• Gas jets create stable liquid surface cavities through a balance of forces.
• Increasing gas jet speed leads to cavity instability, including Rayleigh and Kelvin-Helmholtz instabilities.
• Hydrodynamic stability of gas-liquid cavities remains under-explored despite practical importance.

Purpose of the Study:

• To demonstrate the stabilization of liquid surface cavities using weakly ionized gas.
• To investigate the role of electrohydrodynamic (EHD) gas flow in cavity dynamics.
• To explore the interaction between plasma and deformable dielectric matter.

Main Methods:

• Shadowgraph experiments were conducted to visualize cavity formation and stability.
• Computational two-phase fluid and plasma modeling were employed for detailed analysis.
• The study focused on interfacial dynamics relevant to EHD gas flow, specifically 'electric wind'.

Main Results:

• Weakly ionized gas jets, particularly plasma bullets, expand cavities without destabilization.
• EHD flow from plasma exerts greater force on the liquid surface than neutral gas jets.
• Bidirectional EHD gas flow and parallel electric fields within the cavity enhance surface stability.

Conclusions:

• Plasma-induced forces can stabilize liquid surfaces against gas jet impingement instabilities.
• A novel interdependence between weakly ionized gases and deformable dielectric matter was revealed.
• This research offers insights into plasma-liquid interactions and EHD phenomena.