Circular, Spinning and Paired-Particle Motions of Fine Particles in a Particle Cloud Confined in a High- Frequency Plasma

Charged fine particles are confined in a high-frequency argon plasma and their mo-tions are observed. They show perturbed motions and several particles undergo circular motions. When charged short rods are confined, they stand vertically and shorter rods spin around their vertical axis. For mono-dispersed silica particles, they also form a cloud. Moreover, it is commonly observed that a portion of the particles move in pairs. They fluctuate all the time; however, particles in a pair do not separate nor collide with each other. The mechanism of the motions of paired particles is discussed in relation to local potential structures.