Trapping of plasmons in ion holes
P. K. Shukla, B. Eliasson
Institut für Theoretische Physik IV,
Ruhr-Universität Bochum, D-44780 Bochum, Germany
PACS: 52.35.-g, 94.30.Tz
Abstract
We present analytical and numerical studies of a new electron
plasma wave interaction mechanism which reveals trapping of Langmuir
waves in ion holes associated with non-isothermal ion distribution
functions. This Langmuir-ion hole interaction is a unique kinetic
phenomenon, which is governed by two second nonlinear differential
equations in which the Langmuir wave electric field and ion hole potential
are coupled in a complex fashion. Numerical analyses of our nonlinearly
coupled differential equations exhibit trapping of localized Langmuir wave
envelops in the ion hole which is either standing or moving with sub- or super
ion thermal speed. The resulting ambipolar potential of the ion hole
is essentially negative, giving rise to bipolar slow electric fields.
The present investigation thus offers a new Langmuir wave contraction
scenario that has not been rigorously explored in plasma physics.