Nonlinear Saturation Mechanism of Ion–Ion Instability Due to Particle Trapping Effect

Abstract

The nonlinear saturation mechanism of the ion–ion instability is clarified. Amplitude oscillations is observed in an ion beam-plasma system with a mesh grid as a boundary condition. These amplitude oscillations are caused by multiple energy exchange between the unstable wave and trapped particles. Furthermore, the wave numbers estimated from the saturating length of ion–ion instability's wave-patterns are proportional to \(\sqrt{V_{m}}\), where V m represents a modulating amplitude of test waves. Thus it turns out that the ion–ion instability saturates due to particle trapping effect.