Strong interaction of solitons and their trailing oscillations with resonant beam ions

Strong interaction of ion-acoustic solitons and their trailing oscillations with resonant beam ions in a plasma is experimentally studied. Here, an effective soliton amplification is observed to occur when beam ions with an average energy of about 2 eV collide with the soliton from behind. Furthermore, amplitude dependence of the soliton velocity and width is confirmed to be almost unchanged by such strong interaction with beam ions. In addition, small oscillations behind the soliton are also observed to evolve into a large-amplitude wave train under the influence of resonant beam ions. Finally, some tentative interpretations for these observed phenomena are presented.