The spatial homogeneous and stationary Townsend discharge mode in the planar gas discharge system (experimental setup here) undergoes a spatiotemporal destabilization in the case of a rather high resistance of the GaAs cathode. At a lower resistivity of the cathode, the primary bifurcation is only temporal, leading to a homogeneous oscillation where the spatial homogeneity is maintained.
A spatial destabilization can be detected via the distribution of the light emitted by the gas discharge which indicates the spatial distrubution in the current density. The different stages of patterns in the self-organization process of the gas discharge are illustrated below by some short movies of the spatial dynamics of the discharge glow. In this case, the voltage applied to the system is used as control parameter.

Divergent filaments: The first spatiotemporal destabilization of the Townsend discharge state results in spatial unstable filaments that diverge immediately after they are created.

U₀=655 V

U₀=820 V       U₀=880 V       U₀=910 V


U₀=940 V       U₀=1000 V       U₀=1060 V

To download a complete movie of a pattern - each has a length of about ten seconds (mpeg, app. 1.7 MB) - click on the respective picture.