Amplification of ion-acoustic solitons by an ion beam

Ion-acoustic solutions in a plasma traversed by a weak ion beam are studied experimentally by a double plasma device. Large amplitude compressive pulses are amplified and steepened to become solitons of which the amplitude n/n 0 is comparable or less than 40%. The amplitude of the soliton is maximum at a beam velocity of V b /C s =1.7 while the linear growth rates is maximum at V b /C s =1.3. Theoretical explanations are presented with the use of the fluid model.