Experimental results are presented on the generation and dynamics of concentric as well as non-concentric multiple double layers in hot filament type discharge plasma. These results emphasize striking similarities between the generation and dynamics of both types of multiple double layers, i.e. similar potential steps corresponding to the ionization energy in used gas, similar hysteresis cycles in the current-voltage characteristic of the exciting electrode, similar dynamic behaviour, etc. The results show that a common physical mechanism is at the origin of both phenomena, in which electron-neutral impact excitation and ionization reactions play a key role.

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In certain experimental conditions, in front of a positively biased electrode immersed into a diffusion plasma, a concentric multiple double layers structure can appear. If the electrode is large or asymmetric (one dimension is larger than the others), this structure appears nonconcentrically, as many spherical luminous structures attached to the electrode. Each of these structure consists of a positive nucleus (an ion-rich plasma) bordered by an electrical double layer. The structures are almost equally distributed on the electrode because of the negative external shell of the double layer.

We report experimental results showing that a discharge plasma, which self-structures as concentric multiple double layers, is capable of evolving towards chaos through a cascade of spatio-temporal sub-harmonic bifurcations when the applied constraint (in the form of voltage applied on a supplementary electrode immersed in the plasma) is gradually increased. By considering that the plasma particles (electrons, ions and neutrals) move on fractal curves, a theoretical model able to explain both the plasma self-structuring and the scenario of evolution to chaos is constructed. The experimental results were found to be in good agreement with those obtained from the theoretical model.