  Complex plasmas are interesting systems as the charged dust can self-assemble
into different types of ordered structures. To understand the mechanisms which
govern the transitions from one type of structure to another, it is necessary
to know both the dust charge and the confining electric fields within the
environment, parameters which are difficult to measure independently. The
problem is further complicated by the ion wake field, which develops downstream
of the dust grains in a flowing plasma. The differences in local ion density
caused by the wake field change the equilibrium dust charge and shielding
distance of the dust grains, and thus affect the interaction between grains.
Here we use a molecular dynamics simulation of ion flow past dust grains to
investigate the interaction between the dust particles and ions. We consider a
long vertical chain of particles confined within a glass box placed on the
lower electrode of a GEC rf reference cell. Ions stream from the bulk plasma at
the top of the box to the negative lower electrode. We apply the model
iteratively to self-consistently determine the dust charge, electric field, and
ion density along the length of the chain as well as the ion flow speed.
Simulation results indicate that the ion flow speed within the box is subsonic.
