Micro-dynamics of neutral flow induced dusty plasma flow

TL;DR

This study experimentally investigates how neutral gas flow influences dust particle motion in a plasma, revealing dependencies on flow velocity, pressure, and gas mass, supported by a theoretical force-based model.

Contribution

It provides a detailed experimental analysis of dust flow dynamics in plasma and introduces a simple force-based model to explain neutral gas effects.

Findings

Dust flow velocity increases with neutral flow velocity

Flow velocity decreases with background pressure and gas mass

Flow velocity is independent of dust particle size

Abstract

We present a detailed experimental study of gas flow induced motion of dust particles in a DC glow discharge plasma. The characteristics of the dust dynamics are investigated as a function of the differential gas flow rate, the background neutral pressure, the dust particle size as well as the neutral species of the gas. The experiments have been carried out in the table top Dusty Plasma Experimental (DPEx) device in which a plasma is created between a disk shaped anode and a grounded cathode in a $\Pi$-shaped pyrex glass tube. The asymptotic steady state flow velocity of the injected micron sized dust particles is found to increase with an increase of neutral flow velocity and decrease with an increase in the background pressure. Furthermore, this velocity is seen to be independent of the size of the dust particles but decreases with an increase in the mass of the background gas. A simple theoretical model, based on estimates of the various forces acting on the dust particles, is used to elucidate the role of neutrals in the flow dynamics of the dust particles. Our experiments thus provide a detailed microscopic understanding of some of the past phenomenological observations of dust flows in the DPEx device and can prove useful in future experimental implementations of dust flow experiments.