Langmuir wave excitation by a sheet relativistic electron beam in a homogeneous magnetized plasma

The radiation relaxation of a sheet relativistic electron beam in a homogeneous magnetized plasma is investigated. It is shown that a growing quasi-surface radiating mode is excited in the linear stage of interaction. In the nonlinear stage, the wave-electron synchronism is conserved due to automatic matching of the wave propagation angle, which results in a high efficiency (above 80%) of the energy conversion. (orig.)