Fluid approach to evaluate sound velocity in Yukawa systems (complex plasmas)

TL;DR

This paper presents a fluid-based method to accurately evaluate sound velocity in Yukawa systems, aligning well with previous models and simulations, and highlights the influence of particle correlations and screening effects.

Contribution

A simple fluid approach is proposed to estimate sound velocity in Yukawa fluids, effectively capturing correlation effects and screening influences across coupling regimes.

Findings

Results agree with molecular dynamics simulations

Sound velocity mainly determined by particle correlations

Screening strength significantly affects sound velocity

Abstract

The conventional fluid description of multi-component plasma, supplemented by an appropriate equation of state for the macroparticle component, is used to evaluate the longitudinal sound velocity of Yukawa fluids. The obtained results are in very good agreement with those obtained earlier employing the quasi-localized charge approximation and molecular dynamics simulations in a rather broad parameter regime. Thus, a simple yet accurate tool to estimate the sound velocity across coupling regimes is proposed, which can be particularly helpful in estimating the dust-acoustic velocity in strongly coupled dusty (complex) plasmas. It is shown that, within the present approach, the sound velocity is completely determined by particle-particle correlations and the neutralizing medium (plasma), apart from providing screening of the Coulomb interaction, has no other effect on the sound propagation. The ratio of the actual sound velocity to its "ideal gas" (weak coupling) scale only weakly depends on the coupling strength in the fluid regime, but exhibits a pronounced decrease with the increase of the screening strength. The limitations of the present approach in applications to real complex plasmas are briefly discussed.