Wave propagation in a drifting low-voltage electron beam has been studied. The causes of such a flow instabilities and features of its interaction with the electromagnetic wave have been discussed. The effect of beam cross–sectional velocity variation on the starting conditions BWO has been considered.
$^1$Department of Electronics, Vibrations, and Waves, Faculty of Nonlinear Processes, National Research Saratov State University Saratov 410012, Russia
$^2$National Research Nuclear University MEPhI (Moscow Engineering Physics Institute) Moscow 115409, Russia