Effect of Buffer Gas Induced Friction on the Caging of Particles in a Dusty Plasma

Abstract

In strongly coupled plasmas the diffusion of the particles takes place on a timescale that is long compared to the timescale of oscillations of the particles in the local minima of the potential landscape. The ensuing quasi-stability of the local particle configurations can be quantified by monitoring the changes of the immediate surroundings, i.e. the "cages", of the particles. Studies of cage correlations are presented here for 2-dimensional Yukawa systems that model dusty plasmas by including the friction exerted on the dust particles by the embedding gaseous environment. We find that the increasing friction enhances the caging time by randomizing the directed motion of the particles.

Effect of magnetic field and friction force on the velocity autocorrelation in two‐dimensional Yukawa liquids

“…More details about the influence of the friction force on the VACFs are presented in Figure for Γ = 120, κ = 2, and β = 0.5 (panel (a)), β = 1 (panel [b]) values of the magnetic field parameter. In both cases, the magnitudes of oscillations of the VACFs decrease with an increase in θ , but the frequency remains the same. In this article, we do not investigate the influence of the coupling strength on the normalized VACFs because in ref.…”

“…The latter was found to increase the particle localization time (i.e. the efficiency of “caging”), as revealed by molecular dynamics simulations . In a laboratory dusty plasma, the amplification of an external magnetic field was found to lead to the destruction of ordered structures, owing to its influence on important parameters such as the charge of dust particles.…”

Simultaneous effect of an external magnetic field and gas‐induced friction on the caging of particles in two‐dimensional Yukawa systems

“…When the Larmor radius is smaller than the inter‐particle separation, diffusive motion across the field lines is significantly hindered, and the caging time is enlarged . The effect of friction on the caging time is similar but results from a different physical mechanism. As explained earlier, the presence of the gaseous environment is modelled via a damping mechanism by the background (as a continuum) and by a random (“Brownian”) force that emulates random kicks by gas particles.…”

“…The interplay of these two effects is an open question that can only be answered by a systematic parametric study due to the inherent non‐linearity of the system under investigation. Our studies are based on Langevin dynamics (LD) simulation into which a proper description of the movement of the particles under the influence of an external magnetic field is incorporated …”

Influence of background gas and external magnetic field on the localization of particles in two dimensional yukawa systems

“…The duration of the localization can be quantified by means of the so-called "cage correlation functions". The effect of a static uniform external magnetic field on the cage correlation functions in frictionless two-dimensional Yukawa systems has been investigated by Dzhumagulova et al, [24] while the effect of the friction force, induced by the presence of the buffer gas, has been addressed by Dzhumagulova et al [25] Here, our aim is to study the simultaneous effect of the magnetic field and the friction on the cage correlation functions. The interplay of these two effects is an open question that can only be answered by a systematic parametric study due to the inherent non-linearity of the system under investigation.…”