Low frequency behavior of IREB virtual cathode at plasma injection

Summary form only given. The purpose of the presentation is to clear up the physical pattern of VC evolution at its interaction with an ion stream extracted from plasma. The nonlinear theory of low frequency dynamics of interaction of plasma ions stream with the virtual cathode has been derived. The self-consistent system of the nonlinear integro-differential equations, which describes the LF-relaxation of VC under the action of injected plasma providing ions stream, was obtained and examined by numerical methods. It was shown that in case of conterminous radii of electron and ion beams, the ion stream causes the excitation of coherent wave structure behind the area of electron VC. Accumulation of ions in the system eventually leads to the damping of this structure and forming of laminar electron-ion flow. The radial focusing of ions in the area of electron VC space charge leads to formation of ion VA in the area of focusing. The position of ion focus oscillates with time in longitudinal direction. At the same time electron VC periodically disappears and appears again, that is the reason of deep LF modulation of IREB density.