Instability of ion kinetic waves in a weakly ionized plasma

TL;DR

This paper investigates how ion-neutral collisions and electric fields can destabilize higher-order ion kinetic waves in weakly ionized plasmas, potentially impacting plasma sheath dynamics.

Contribution

It demonstrates that ion-neutral collisions and electric fields can induce instability in ion kinetic modes, a novel insight into plasma wave behavior in weakly ionized conditions.

Findings

Ion-neutral collisions modify plasma wave damping.

Electric fields can drive instability in ion modes.

Instability likely affects plasma sheath structures.

Abstract

The fundamental higher-order Landau plasma modes are known to be generally heavily damped. We show that these modes for the ion component in a weakly ionized plasma can be substantially modified by ion-neutral collisions and a dc electric field driving ion flow so that some of them can become unstable. This instability is expected to naturally occur in presheaths of gas discharges at sufficiently small pressures and thus affect sheaths and discharge structures.