Evolution of Ion Wake Characteristics with Experimental Conditions

Abstract

Two-dimensional microparticle crystals can be formed in the sheath of a gas discharge plasma. Ions from the bulk plasma are accelerated in the sheath electric field, flowing past the grains to create a positive ion wake downstream from the grains. Interaction between the ion wake and neighboring grains creates additional coupling between oscillation modes and can trigger mode-coupling instability (MCI). Recent experiments have shown that at a fixed discharge power there are threshold pressures above and below which the monolayer always crystallizes or melts, respectively. The melting is due to MCI being triggered in the crystal monolayer, while the crystallization is due to the suppression of MCI by neutral damping in the fluid monolayer. The relationship between the discharge parameters and ion wake characteristics is unknown. A molecular dynamics simulation of ion dynamics and dust charging is used to self-consistently determine the dust charge and ion wake characteristics for different experimental conditions. It is found that the ion wake is strongly dependent on discharge pressure but not affected much by the discharge power.

References in corpus (7)

• Crystallization dynamics of a single layer complex plasma
• Mode coupling and resonance instabilities in quasi-two-dimensional dust clusters in complex plasmas
• Mode couplings and resonance instabilities in dust clusters
• Stability of two-dimensional complex plasma monolayers in asymmetric capacitively-coupled radio-frequency discharges
• Effect of ionization waves on dust chain formation in a DC discharge
• Influence of Temporal Variations in Plasma Conditions on the Electric Potential Near Self-Organized Dust Chains
• Experiment and model for a Stokes layer in a strongly coupled dusty plasma