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| Titel |
The dynamics of electron and ion holes in a collisionless plasma |
| VerfasserIn |
B. Eliasson, P. K. Shukla |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1023-5809
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| Digitales Dokument |
URL |
| Erschienen |
In: Nonlinear Processes in Geophysics ; 12, no. 2 ; Nr. 12, no. 2 (2005-02-11), S.269-289 |
| Datensatznummer |
250010489
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| Publikation (Nr.) |
 copernicus.org/npg-12-269-2005.pdf |
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| Zusammenfassung |
| We present a review of recent analytical and numerical studies of
the dynamics of electron and ion holes in a collisionless plasma.
The new results are based on the class of analytic solutions which
were found by Schamel more than three decades ago, and which here
work as initial conditions to numerical simulations of the
dynamics of ion and electron holes and their interaction with
radiation and the background plasma. Our analytic and numerical
studies reveal that ion holes in an electron-ion plasma can trap
Langmuir waves, due the local electron density depletion
associated with the negative ion hole potential. Since the
scale-length of the ion holes are on a relatively small Debye
scale, the trapped Langmuir waves are Landau damped. We also find
that colliding ion holes accelerate electron streams by the
negative ion hole potentials, and that these streams of electrons
excite Langmuir waves due to a streaming instability. In our
Vlasov simulation of two colliding ion holes, the holes survive
the collision and after the collision, the electron distribution
becomes flat-topped between the two ion holes due to the ion hole
potentials which work as potential barriers for low-energy
electrons. Our study of the dynamics between electron holes and
the ion background reveals that standing electron holes can be
accelerated by the self-created ion cavity owing to the positive
electron hole potential. Vlasov simulations show that electron
holes are repelled by ion density minima and attracted by ion
density maxima. We also present an extension of Schamel's theory
to relativistically hot plasmas, where the relativistic mass
increase of the accelerated electrons have a dramatic effect on
the electron hole, with an increase in the electron hole potential
and in the width of the electron hole. A study of the interaction
between electromagnetic waves with relativistic electron holes
shows that electromagnetic waves can be both linearly and
nonlinearly trapped in the electron hole, which widens further due
to the relativistic mass increase and ponderomotive force in the
oscillating electromagnetic field. The results of our simulations
could be helpful to understand the nonlinear dynamics of electron
and ion holes in space and laboratory plasmas. |
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