Anisotropic confinement effects in a two-dimensional plasma crystal

TL;DR

This paper investigates how anisotropic confinement influences wave energy distribution and phonon flux in two-dimensional plasma crystals, combining theoretical analysis and molecular-dynamics simulations.

Contribution

It provides a theoretical and simulation-based explanation for spectral asymmetry and preferred particle motion directions caused by anisotropic confinement.

Findings

Anisotropic confinement causes spectral asymmetry in wave energy distribution.

Preferred particle motion directions are linked to anisotropic phonon flux.

Differences in wave intensity are explained by anisotropic phonon scattering mechanisms.

Abstract

The spectral asymmetry of the wave energy distribution of dust particles during mode-coupling induced melting, observed for the first time in plasma crystals by Cou\"edel et al. [Phys. Rev. E 89, 053108 (2014)], is studied theoretically and by molecular-dynamics simulations. It is shown that an anisotropy of the well confining the microparticles selects the directions of preferred particle motion. The observed differences in intensity of waves of opposed directions is explained by a nonvanishing phonon flux. Anisotropic phonon scattering by defects and Umklapp scattering are proposed as possible reasons for the mean phonon flux.