Excitation of dust acoustic shock waves in an inhomogeneous dusty plasma

TL;DR

This paper experimentally studies shock wave propagation in an inhomogeneous dusty plasma, revealing how shock amplitude and width change with background density, supported by a theoretical model based on a modified KdV-Burger equation.

Contribution

It introduces the first experimental investigation of shock waves in inhomogeneous dusty plasma and develops a theoretical model explaining the observed behavior.

Findings

Shock amplitude increases with propagation

Shock width broadens as it moves into lower density regions

Theoretical model matches experimental scaling laws

Abstract

An experimental investigation of the propagation characteristics of shock waves in an inhomogeneous dusty plasma is carried out in the Dusty Plasma Experimental (DPEx) device. A homogeneous dusty plasma, made up of poly-dispersive kaolin particles, is initially formed in a DC glow discharge Argon plasma by maintaining a dynamic equilibrium of the pumping speed and the gas feeding rate. Later, an equilibrium density inhomogeneity in the dust fluid is created by introducing an imbalance in the original dynamic equilibrium. Non-linear wave structures are then excited in this inhomogeneous dusty plasma by a sudden compression in the dust fluid. These structures are identified as shock waves and their amplitude and width profiles are measured spatially. The amplitude of a shock structure is seen to increase whereas the width broadens as it propagates down a decreasing dust density profile. A modified-KdV-Burger equation is derived and used to provide a theoretical explanation of the results including the power law scaling of the changes in the amplitude and width as a function of the background density.