Interacting Solitons in a Nonneutral Plasma

We have been continuing our study of solitons and nonlinear interactions in a pure electron plasma. The solitons are grown from large amplitude normal-mode oscillations. When grown in this way, it is convenient to divide the resulting wave into two parts: localized soliton-like structures and global normal-mode-like waves. These two parts interact weakly with each other and cause various interesting effects. When we launch two solitons by using the n, = 2 mode, the normal mode part quickly converts to an nz = 1 mode and causes one of the solitions to disappear. Later, when only one solition exists, the nz = 1 mode is locked to it. Because the soliton speed is faster than the linear wave speed, this increases the frequency of the normal-mode part of the system. It appears that when the soliton amplitude drops below some critical value, the two parts of the system decouple and propagate separately.