Time Evolution of Two Ring Dust Chains

Abstract:

A strongly coupled two-ring dust chain of micron sized particles will regularly form in a R-F generated plasma under the proper conditions. When the rings are in a high energy state the dynamics of the particles is dominated by random thermal motions. As the energy of the system is reduced the particles eventually settle into two dimensional dust chains. The time evolution of these particles from high energy random thermal motion to regular lattice structures under rapid cooling conditions has been investigated using motion tracking techniques. As the system cools, the dust particles shift and rotate in a two-dimensional plane in order to achieve an equilibrium position. Analysis shows that most particle shifts are local involving only a few particles, though some adjustments are global and involve most of the particles in the cluster. Laser induced acoustic (longitudinal) waves have also been observed in the two ring system and the dispersion relation is compared to theory.