Dust acoustic waves in three-dimensional complex plasmas with a similarity property

TL;DR

This paper develops a theoretical model for dust acoustic waves in three-dimensional complex plasmas, incorporating ionization similarity, and validates it with experimental data, providing insights into wave behavior under microgravity conditions.

Contribution

It introduces a new theoretical framework based on ionization similarity for analyzing dust acoustic waves in complex plasmas, including damping effects and predictions for space experiments.

Findings

Sound velocity depends on particle compressibility derived from IEOS.

The model accurately predicts experimental sound velocities and damping rates.

Independence of sound velocity from position and weak dependence on particle size and pressure.

Abstract

Dust acoustic waves in the bulk of a dust cloud in complex plasma of low-pressure gas discharge under microgravity conditions are considered. The complex plasma is assumed to conform to the ionization equation of state (IEOS) developed in our previous study. This equation implies the ionization similarity of plasmas. We find singular points of IEOS that determine the behavior of the sound velocity in different regions of the cloud. The fluid approach is utilized to deduce the wave equation that includes the neutral drag term. It is shown that the sound velocity is fully defined by the particle compressibility, which is calculated on the basis of the used IEOS. The sound velocities and damping rates calculated for different three-dimensional complex plasmas both in ac and dc discharges demonstrate a good correlation with experimental data that are within the limits of validity of the theory. The theory provides interpretation for the observed independence of the sound velocity on the coordinate and for a weak dependence on the particle diameter and gas pressure. Predictive estimates are made for the ongoing PK-4 experiment.