Wide Solitons in an Ion-Beam-Plasma System.

Abstract

Solitons are experimentally found in a double plasma device when an ion beam is present with beam velocity ${v}_{b}$ in the range $1\ensuremath{\le}{v}_{b}{/c}_{s}\ensuremath{\le}2.2$, where ${c}_{s}$ is the ion acoustic velocity. These one dimensional solitons have an unusually large width (parallel to the direction of propagation) $W\ensuremath{\approx}14{\ensuremath{\lambda}}_{D}(\ensuremath{\delta}n/n{)}^{\ensuremath{-}1/2}$, where ${\ensuremath{\lambda}}_{D}$ is the Debye length and $\ensuremath{\delta}n/n$ is the maximum normalized density fluctuation. The amplitude, width, and velocity characteristics of the solitons are found to be in good agreement with the soliton solution to the Korteweg--de Vries equation in an ion-beam--plasma system.