  Dust particles immersed in a plasma environment become charged through the
collection of electrons and ions at random times, causing the dust charge to
fluctuate about an equilibrium value. Small grains (with radii less than 1
\mum) or grains in a tenuous plasma environment are sensitive to single
additions of electrons or ions. Here we present a numerical model that allows
examination of discrete stochastic charge fluctuations on the surface of
aggregate grains and determines the effect of these fluctuations on the
dynamics of grain aggregation. We show that the mean and standard deviation of
charge on aggregate grains follows the same trends as those predicted for
spheres having an equivalent radius, though aggregates exhibit larger
variations from the predicted values. In some plasma environments, these charge
fluctuations occur on timescales which are relevant for dynamics of aggregate
growth. Coupled dynamics and charging models show that charge fluctuations tend
to produce aggregates which are much more linear or filamentary than aggregates
formed in an environment where the charge is stationary.
