Dynamic stabilization of plasmas by means of a high-frequency-modulated electron beam

The stabilizing effects that a beam of longitudinally nonuniform density imposes on beam-plasma instabilities are investigated using a hydrodynamic model adapted for an infinite, one-dimensional beam-plasma system. The electron beam is characterized by either of two types of longitudinal inhomogeneity—square-wave or sinusoidal. The results, for the square-wave type of inhomogeneity, indicate a disappearance of the convective instabilities below a threshold frequency as well as a reduction in the growth rate for the remainder of the spectrum. Similar results are obtained for the case of a high-frequency sinusoidal pulsation of the beam density. Effects resulting from finite temperature plasma electrons are also discussed.