  The propagation mechanisms of plasma streamers have been observed and
investigated in a surface dielectric barrier discharge (SDBD) using 2D particle
in cell simulations. The investigations are carried out under a simulated air
mixture, 80\% N$_2$ and 20\% O$_2$, at atmospheric pressure, 100$\,$kPa, under
both DC conditions and a pulsed DC waveform that represent AC conditions. The
simulated geometry is a simplification of the symmetric and fully exposed SDBD
resulting in the simultaneous ignition of both positive and negative streamers
on either side of the Al$_2$O$_3$ dielectric barrier. In order to determine the
interactivity of the two streamers, the propagation behavior for the positive
and negative streamers are investigated both independently and simultaneously
under identical constant voltage conditions. An additional focus is implored
under a fast sub nanosecond rise time square voltage pulse alternating between
positive and negative voltage conditions, thus providing insight into the
dynamics of the streamers under alternating polarity switches. It is shown that
the simultaneous ignition of both streamers, as well as using the pulsed DC
conditions, provides both an enhanced discharge and an increased surface
coverage. It is also shown that additional streamer branching may occur in a
cross section that is difficult to experimentally observe. The enhanced
discharge and surface coverage may be beneficial to many applications such as,
but are not limited to: air purification, volatile organic compound removal,
and plasma enhanced catalysis.
