Experimental observation of multiple double Layers structures in Plasma-part I: concentric multiple double Layers

By applying a positive potential on an electrode immersed in plasma, a complex space charge configuration can be obtained in front of it. Diagnosis methods prove that this structure consist of a positive nucleus (an ion-rich plasma) surrounded by an electrical double layer. Under certain experimental conditions, a more complex structure in form of two or more subsequent double layers was observed. It appears as several bright and concentric plasma shells attached to the electrode. The successive double layers are precisely located at the abrupt changes of luminosity between two adjacent plasma shells.