ALIGNMENT AND INSTABILITY OF DUST CRYSTALS IN PLASMAS

Charged dust particulates, forming a layered crystal in the electrode sheath of a rf discharge, are known to show vertical alignment and an onset of characteristic oscillations below a threshold of neutral gas density. Here forces on the particulates due to the formation of posit ive space-charge clouds below the dust particles are calculated from M onte Carlo calculations of the ion motion in the sheath. The forces ar e shown to be attractive and nonreciprocal for the different crystal l ayers; From the Monte Carlo results an analytical lattice model is der ived that quantitatively explains the experimental findings.