Dust chains in the strongly coupled liquid regime*

In many environments, ions in the plasma have a directed flow with respect to charged dust grains resulting in an ion wakefield downstream from the dust. The positive space-charge region modifies the interaction between the grains and contributes to the observed dynamics and particle structure. The weak wakefield force is usually masked by gravity in ground experiments, but microgravity experiments conducted in the PK-4 on board the International Space Station allow the ion-wake mediated force to be investigated. Here we report results of coupled numerical models of the plasma discharge, ion wakefield and particle interactions in the PK-4.  The discharge conditions are modeled by an axisymmetric PIC/MCC and hybrid discharge simulation. Local plasma parameters are used as inputs for an N-body code modeling the dynamics of the ions in the time-varying electric field within the DC discharge and their interaction with the charged dust. Charging and dynamics of the grains are self-consistently derived from the ion-dust interactions. Exploring the conditions which lead to the formation of field-aligned dust chains yields insight into the phenomena which govern the strongly coupled liquid phase.