Ion-acoustic wave evolution in an inhomogeneous flowing plasma

The excitation of ion-acoustic waves with a grid immersed in an inhomogeneous flowing plasma was studied experimentally. Consideration of the effects of the ion flow was examined. The experiments indicated that there were two features of distinct interest. First, there could be a significant difference in the received signals if the wave was launched along or against the direction of the plasma flow. Second, the dominant “propagating response” whose waveform resembled the time derivative of the applied voltage signal was excited at low excitation frequencies.