Soliton Modes in an Unstable Plasma

Abstract

A synergetic approach is applied to the study of nonlinear evolution of unstable waves in an electron beam plasma. When the beam velocity is sufficiently large compared with the thermal velocity of electrons, the system is linearly unstable against electrostatic perturba· tions of large wavelengths, but stabilized in its nonlinear stage by the effect of ponderomotive force of high·frequency fields. The results show that the amplitude of unstable plane wave behaves such as ~sech rt as a function of time t, where r is the linear growth rate, never growing up infinitely. It is also shown that the plane wave is unstable for long wavelength modulation and is stabilized by emission of a series of envelope solitons.