Collective excitations of a spherically confined Yukawa plasma

TL;DR

This paper compares fluid theory predictions with molecular dynamics simulations and exact eigenmodes for multipole excitations in a confined Yukawa plasma, analyzing effects of screening, coupling, and friction.

Contribution

It validates fluid theory predictions against simulations and eigenmodes, providing detailed analysis of mode spectra and their dependencies in Yukawa plasmas.

Findings

High order modes confirmed by simulations

Good agreement for weak to moderate screening

Relations between fluid, simulation, and crystal modes clarified

Abstract

The results of a recent fluid theory for the multipole modes of a Yukawa plasma in a spherical confinement [H. K\"{a}hlert and M. Bonitz, Phys. Rev. E \textbf{82}, 036407 (2010)] are compared with molecular dynamics simulations and the exact $N$-particle eigenmodes in the crystalline phase. Simulations confirm the existence of high order modes found in cold fluid theory. We investigate the influence of screening, coupling and friction on the mode spectra in detail. Good agreement between theory and simulation is found for weak to moderate screening and low order modes. The relations between the breathing mode in the fluid theory, simulation and the crystal eigenmode are investigated in further detail.