Direct Measurements of Particle Transport in dc Glow Discharge Dusty Plasmas

Many recent experiments in dc glow discharge plasmas have shown that clouds of dust particles can be suspended near the biased electrodes. Once formed, the dust clouds have well defined boundaries while particle motion within the clouds can be quite complex. Because the dust particles in the cloud can remain suspended in the plasma for tens of minutes, it implies that the particles have a low diffusive loss rate and follow closed trajectories within the cloud. In the experiments discussed in this paper, direct measurements of the dust particle velocities are made using particle image velocimetry (PIV) techniques. From the velocity measurements, a reconstruction of the three- dimensional transport of the dust particles is performed. A qualitative model is developed for the closed motion of the dust particles in a dc glow discharge dusty plasma.