String structures in driven 3D complex plasma clusters

TL;DR

This study experimentally investigates the structure and dynamics of driven 3D complex plasma clusters, revealing unique string formations and their correlations, and compares these findings with recent simulations.

Contribution

It introduces experimental analysis of driven 3D plasma clusters with controlled manipulation and compares observed structures to recent simulation results.

Findings

Clusters form strings of 2 to 5 particles.

Clusters can rotate or stay stationary depending on excitation frequency.

Observed structures differ from nested shells or simple chains.

Abstract

The structure of driven three-dimensional complex plasma clusters was studied experimentally. The clusters consisted of around 60 hollow glass spheres with a diameter of 22 microns that were suspended in a plasma of rf discharge in argon. The particles were confined in a glass box with conductive yet transparent coating on its four side walls, this allowed to manipulate the particle cluster by biasing the confining walls in a certain sequence. In this work, a rotating electric field was used to drive the clusters. Depending on the excitation frequency, the clusters rotated (10^4 - 10^7 times slower than the rotating field) or remained stationary. The cluster structure was neither that of nested spherical shells nor simple chain structure. Strings of various lengths were found consisting of 2 to 5 particles, their spatial and temporal correlations were studied. The results are compared to recent simulations.