Effect of trapped beam electrons on nonlinear beam-plasma interaction

The experimental and theoretical results of a study of the Cherenkov type ( omega approximately=k/sub ///v b ) of nonlinear interaction of a cold electron beam with a magnetized plasma are discussed. In the initial stage, a single quasi-monochromatic wave determining the dynamics of the nonlinear interaction is excited in the system. In this case the energy released by the retardation of the beam as a whole is transferred mainly to the excited wave and the problem may be solved numerically. Experimentally, the averaged beam distribution function in various stages of the interaction, the phase velocity of the excited wave and the spatial dependence of its amplitude have been measured. Satellites of the basic wave have been observed and their frequencies determined. In those regimes in which a single strong wave is excited an agreement between the calculated and measured values has been found.