Nonlinear electron beam interaction with a whistler wave packet

The nonlinear evolution of a thin monoenergetic electron beam injected in a magnetized plasma and interacting with a whistler wave packet through Cher enkov resonance is considered. It is shown that effective dissipation due t o whistlers' wave field leakage out of the bounded beam volume to infinity (effective radiation outside the beam) strongly influences the evolution of the beam electrons' distribution. Self-organization of beam structure lead s to the formation of electron bunches continuously decelerated by waves. I n the presence of effective energy losses, the phases of all waves in the p acket can become strongly correlated and thus can prevent the stochastic ph ase mixing required for validity of quasilinear theory. In the asymptotic s tage of the beam-waves interaction, dynamically stable electron bunches are present together with a diffusion plateau in the velocity distribution; th ese nonlinear structures allow the beam to radiate wave energy on a signifi cative distance from its injection point. (C) 2000 American Institute of Ph ysics. [S1070-664X(00)00311-6].