Sideband Instability: Observations and Comparison with Theory

Abstract

In the trapped-electron sideband instability of a nonlinear plasma wave of potential ${\varphi }_0$, initial enhanced damping occurs for a distance $\propto {{\varphi }_0}^{-\frac{1}{2}}$, beyond which signals grow at a rate scaling nearly linearly with ${\varphi }_0$. The growth remains exponential even in cases where the main wave is significantly damped. This behavior is more consistent with a quasilinear spectral development than with the commonly cited parametric bounce-frequency instability of a stationary Bernstein-Greene-Kruskal equilibrium.