Bidirectional flow of two-dimensional dusty plasma under asymmetric periodic substrates driven by unbiased external excitations

TL;DR

This study uses simulations to explore how unbiased sinusoidal forces and asymmetric substrates influence particle flow in dusty plasma, revealing controllable flow direction, speed, and ratchet effects due to symmetry breaking and inertia.

Contribution

It demonstrates how external excitation parameters can control particle transport and induce ratchet effects in dusty plasma with asymmetric substrates, a novel insight into plasma manipulation.

Findings

Flow direction and speed can be tuned by excitation amplitude and frequency.

Ratchet effects cause flow rectification and reversal in dusty plasma.

Maximum drift velocities depend on substrate depth and excitation parameters.

Abstract

Collective transport properties of a one-dimensional asymmetric periodic substrate (1DAPS) modulated two-dimensional dusty plasma (2DDP) driven by an unbiased sinusoidal excitation force are investigated using Langevin dynamical simulations. It is discovered that, by changing the amplitude and frequency of the unbiased sinusoidal external excitations, as well as the depth of 1DPAS, both the direction and speed of the persistent particle flow can be adjusted, i.e., both the flow rectification and its reversal of the ratchet effect of the steady drift motion for particles are achieved using various excitations. For the studied 2DDP under the 1DAPS, when the amplitude of the excitation increases from zero, the magnitude of the overall drift velocity increases from zero to its first maximum in the easy direction of the 1DAPS, next decreases gradually back to zero, and then increases from zero to its second maximum in the hard direction of 1DAPS before finally gradually decaying. It is found that, as the frequency of the excitation and the depth of 1DAPS change, the maximum overall drift velocity also varies, and the corresponding magnitude of the excitation varies simultaneously. The observed ratchet effect in both the easy and hard directions of 1DAPS for 2DDP is attributed to the combination of the spatial symmetry breaking of 1DAPS and the inertial effects of particles, which is further confirmed by the three different presented diagnostics.