  Drift-diffusion plasma fluid models are commonly used to simulate electric
discharges. Such models can computationally be very efficient if they are
combined with explicit time integration. This paper deals with two issues that
often arise with such models. First, a high plasma conductivity can severely
limit the time step. A fully explicit method to overcome this limitation is
presented. This method is compared to the existing semi-implicit method, and it
is shown to have several advantages. A second issue is specific to models with
the local field approximation. Near strong density and electric field
gradients, electrons can diffuse parallel to the field, and unphysically
generate ionization. Existing and new approaches to correct this behavior are
compared. Details on the implementation of the models and the various
approaches are provided.
