MODULATION OF INTEGRAL FIELD OF MULTIMODE BEAM INSTABILITIES IN PLASMA

Abstract

The paper discusses the character of the integral field excited by the non– relativistic electron beam in a multimode regime under the finite level of oscillations absorption. The modulation of the field in the frame of the beam at the initial stage of instability is negligible for small absorption levels. The field in the laboratory frame at fixed points varies slightly, the oscillation frequency decreases slightly in a wide range of changes in the absorption level. In the case of dissipative regimes of beam instability the initial distribution of field forms a wave packet, moving synchronously with the area of beam perturbations. In the laboratory reference frame the field, at least at the initial stage of the process, is a sequence of pulses whose duration increases with time.