Nonlinear Theory of the Instability of a Modulated Electron Beam of Low Density in a Plasma IV. Excitation of Nonresonant Waves

Abstract

AbstractA system of nonlinear equations derived in a previous paper which describes the evolution of nonresonant waves in beam‐plasma systems is solved numerically. It is given a physical interpretation of essential features of the nonresonant beam‐plasma instability. The significant influence of higher harmonics on the evolution of an electron beam in the plasma which is modulated on a nonresonant unstable frequency, is investigated. The interaction of unstable nonresonant and resonant waves in beam‐plasma systems is examined. It is shown that the evolution of resonant waves can be essentially influenced by an initial modulation of the beam on an unstable non‐resonant frequency. The role of an initial velocity modulation of the beam for the influence of the wave spectrum is demonstrated.