Interaction of a precursor soliton with wake structure in a flowing dusty plasma

Abstract

We report experimental observations on the interaction of a precursor soliton with a wake structure in a flowing dusty plasma system. The experiments are carried out in an inverted ∏-shaped experimental device in which a dusty plasma is created in a direct current glow discharge Ar plasma using micrometer sized Kaolin particles. Two copper wires installed radially on the cathode serve as charged objects in the plasma environment. Precursor solitons and wake structures are excited by each of the charged objects when the dust fluid flows supersonically over both the objects. In the frame of the fluid, the solitons propagate in the upstream direction, whereas the smaller amplitude wake structures propagate in the downstream direction. A soliton, excited by one of the objects, interacts with the wake structure generated by the other object in the region between the two charged objects. After the interaction, the amplitude and velocity of the soliton increase whereas its width decreases. The results are explained theoretically using numerical solutions of a model forced Korteweg-de Vries equation driven by two source terms.