Hexagon structures in a two-dimensional dc-driven gas discharge system

In a dc-driven planar gas discharge semiconductor system, self-organization phenomena have been investigated experimentally. The spatial structures we focus on appear as a spatial modulation of the transversal distribution of the electric current density. These patterns have been observed and recorded through a transparent electrode with spatial resolution via their corresponding light emission. When choosing appropriate experimental conditions, the initially homogeneous current density distribution undertakes a transition to a periodic hexagon and then to a stripe pattern. This behavior of the experimental system is investigated quantitatively and is discussed in the frame of a phenomenological model.