Effect of burst ions on the excitation of ion-acoustic solitons in a drifting plasma

The characteristics of fast burst ions and ion-acoustic solitons in a drifting plasma, as well as their interaction, are investigated experimentally. It is shown that the soliton evolves from the normal fast ion-beam mode excited locally in the presheath region of an excitation grid. The burst ions are created by applying a positive ramp voltage to the grid. Adjusting the rise time and amplitude of the ramp signal can lead to significant changes in the average speed of the burst ions, resulting in strong interaction (inverse Landau damping) between the burst ions and the soliton. The resonance conditions for solitons propagating along and against the plasma flow are shown to be different, since the soliton speed depends on the propagation direction. (C) 2007 American Institute of Physics.