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Ion-acoustic solitons can be generated during the nonlinear evolution of a
plasma fluid. Motivated by recent experimental observations, in which
electrostatic solitary structures were detected in laser-plasma experiments
[1], we have undertaken an investigation of the nonlinear dynamics of plasma
evolving in two dimensions, in the presence of excess superthermal background
electrons. The effect of a magnetic field on weakly nonlinear ion acoustic
waves is investigated. Nonlinear propagation of the ion-acoustic (IA) shock
waves in a non-thermal magnetised plasma is shown to be governed by a hybrid
Zakharov - Kuznetsov/Burgers-type equation, where dissipation is modelled via
an ad hoc damping term. A reductive perturbation technique (RPT) is used to
derive the KdVB-ZK equation. Different types of shock solutions are obtained,
depending on the relation between the system parameters. Excess
superthermality of the electrons is considered via a kappa-type distribution,
and the effect of excess superthermality on electrostatic shock structures is
investigated numerically.
[1] Marco Borghesi, Gianluca Sarri and collaborators, Queen's University Belfast. [2] Rowlands' book. |
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