Excitation of ion acoustic collisionless shock by a moving obstacle

The ion acoustic wave modulation induced by a steadily moving obstacle (charged density object) is studied in collisionless, unmagnetized, and homogeneous plasmas. In the weakly nonlinear and high dispersive limit, the modulated disturbance induced excitation is shown to be described by a forced/driven nonlinear Schrödinger equation that is solved exactly for some special analytical forms of the driven term. A more interesting and striking phenomenon predicted by the computation is the excitation of the ion acoustic shock at a supersonic relative speed of the obstacle. The results are in good agreement with the observations in low altitude auroral plasmas. The relevance and potential applications of the results in future plasma experiments are also discussed.