Long-term spatio-temporal evolution of the dust distribution in dusty argon rf plasmas

Abstract

The 3D dust distribution in dense dust clouds confined in argon rf plasmas is measured by a computed tomography (CT) technique based on the extinction of visible light. On the one hand, clouds of micron-sized particles were created by injecting standardized plastic particles into the plasma. On the other hand, sub-micron sized dust with well-defined properties is grown in situ in an argon acetylene mixture. Once created, both kinds of dust clouds decay in the course of minutes to hours. This decay is monitored by CT measurements. It is revealed that micro-dust clouds feature a drastic change of the dust distribution due to a size reduction of the dust. Dust clouds of sub-micron particles, in contrast, show a strong variation of the overall dust density while the relative dust distribution remains nearly unchanged. The evolution of the overall dust density is subject to two effects: the loss of particles due to an imperfect confinement and the reduction of the dust size via etching.