  Numerical simulations of monolayer dust crystals in an RF complex plasma were
performed to examine the crystal structure and quantify the effects of
including the collision enhanced ion current in the charging model. A GEC cell
similar to a previous experimental work was modeled for a range of RF voltages,
using a continuum description for the plasma and a particle description for
dust grains. The time history of each dust grain was monitored. The dust charge
was computed using both the OML and the collision enhanced charging (CEC) model
applicable to the sheath region. The dust model accounted for the electric
force, ion drag force, neutral drag force, gravity, and the ion wake. The CEC
model produced a lower charge and lower electric force which agreed better with
the experimental data. Then dust crystals composed of 40 to 100 grains were
modeled and the levitation height and inter-particle spacing of the resulting
crystals was examined. Including the collision enhanced current reduced the
inter-particle spacing but only had a minor effect on the levitation height.
