Spatiotemporal evolution of a self-excited dust density wave in a nanodusty plasma under strong Havnes effect

TL;DR

This study investigates the spatiotemporal evolution of self-excited dust density waves in a nanodusty plasma with high particle density, revealing inhomogeneous propagation, decreasing phase velocity, and wave merging phenomena influenced by the Havnes effect.

Contribution

It provides the first detailed experimental analysis of dust density wave evolution in nanodusty plasma under strong Havnes effect, including wave merging and charge reduction insights.

Findings

Wave propagation is inhomogeneous across the dust cloud.

Phase velocity decreases along the propagation direction.

Wave merging phenomena are observed and analyzed.

Abstract

A broad-spectrum self-excited dust density wave is experimentally studied in a vertically extended nanodusty plasma consisting of in situ grown carbonaceous nanometer sized particles. The nanodusty plasma having high particle density (of the order of 10^12-10^13 m^(-3)) is created with vertical extension up to (40+-0.1) cm and radial extension up to (5+-0.1) cm. The propagation of the self-excited dust density wave under strong Havnes effect is examined over a large axial distance (19+-0.1) cm. Time-resolved Hilbert transformation and Fast Fourier transformation techniques are used to study the spatiotemporal evolution of frequency and wave numbers along three directions from the dust void viz. axial, radial and oblique. The propagation is found to be inhomogeneous throughout the dust cloud. The phase velocity of the wave is estimated to be quite low and decreasing along the direction of propagation. This effect is attributed to the strong reduction of particle charge due to a high Havnes parameter along the propagation direction. By the estimation of average particle charge, ion density and the finite electric field throughout the nanodust cloud, a quantitative analysis of the void formation in nanodusty plasma is presented. New insights are also made regarding wave merging phenomena using time-resolved Hilbert transformation.