Energy landscape in 3D finite dust clusters derived from shell transitions

Experiments on three-dimensional (3D) spherical arrangements of charged dust particles in a plasma confinement (Yukawa balls) are presented. The plasma trap provides a 3D isotropic harmonic confinement in which a small number of dust particles, N < 100, are trapped. The particle arrangement is recorded using stereoscopic imaging. Transitions between different configurations of Yukawa balls are observed that allow us to determine the energy landscape in such a finite cluster. The experiments have been compared to molecular dynamics (MD) simulations with very good agreement. (Some figures in this article are in colour only in the electronic version)