Nonlinear wave phenomena in an electron-beam plasma

An experiment has been carried out for investigating one-dimensional nonlinear evolution and formation of localized structure of unstable waves in an electron-beam plasma. The plasma system is linearly unstable against electrostatic perturbations of frequencies lower than the critical frequency omega(cr) (similar or equal to omega(pe), plasma frequency), but is stabilized in its nonlinear stage by generating wave packets irregularly. The amplitude of each wave packet never grows up infinitely. The average time width of packets is inversely proportional to the linear growth rate gamma, where gamma proportional to (n(b)/n(o)) (1/3)omega(pe). The system is also unstable for an external rf-disturbance, and then finally becomes stable by emission of a series of burst waves.