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arXiv · 1107.5226

Electron-acoustic solitary waves in the presence of a suprathermal electron component

Ashkbiz Danehkar·Nareshpal Singh Saini·Manfred A. Hellberg·Ioannis Kourakis
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Abstract

The nonlinear dynamics of electron-acoustic localized structures in a collisionless and unmagnetized plasma consisting of "cool" inertial electrons, "hot" electrons having a kappa distribution, and stationary ions is studied. The inertialess hot electron distribution thus has a long-tailed suprathermal (non-Maxwellian) form. A dispersion relation is derived for linear electron-acoustic waves. They show a strong dependence of the charge screening mechanism on excess suprathermality (through κ). A nonlinear pseudopotential technique is employed to investigate the occurrence of stationary-profile solitary waves, focusing on how their characteristics depend on the spectral index κ, and the hot-to-cool electron temperature and density ratios. Only negative polarity solitary waves are found to exist, in a parameter region which becomes narrower as deviation from the Maxwellian (suprathermality) increases, while the soliton amplitude at fixed soliton speed increases. However, for a constant value of the true Mach number, the amplitude decreases for decreasing κ.

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Ashkbiz Danehkar, Nareshpal Singh Saini, Manfred A. Hellberg, Ioannis Kourakis. 2011-07-26. Electron-acoustic solitary waves in the presence of a suprathermal electron component. https://doi.org/10.1063/1.3606365

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