Stereoscopic particle image velocimety is used to make measurements of the formation of a dust cloud of $1.2\mu \mathrm{m}$ alumina particles in an argon dc glow discharge plasma. These measurements show a clear redistribution of particle velocities during the cloud formation process. Furthermore, these measurements suggest that the particle cloud reaches an equilibrium on a time scale over 100 times slower than expected due to neutral-drag effects.

• Received 9 February 2005

DOI:https://doi.org/10.1103/PhysRevLett.95.055001