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 ). 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 , 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 .
Original language | English |
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Article number | 072902 |
Journal | Physics of Plasmas |
Volume | 18 |
Issue number | 7 |
DOIs | |
State | Published - Jul 2011 |
Externally published | Yes |
Funding
A.D. warmly acknowledges support from the Department for Employment and Learning (DEL) Northern Ireland via a postgraduate scholarship at Queen’s University Belfast. The work of IK and NSS was supported via a Science and Innovation (S & I) grant to the Centre for Plasma Physics (Queen’s University Belfast) by the UK Engineering and Physical Sciences Research Council (EPSRC Grant No. EP/D06337X/1). The work of M.A.H. is supported in part by the National Research Foundation of South Africa (NRF). Any opinion, findings, and conclusions or recommendations expressed in this material are those of the authors and therefore the NRF does not accept any liability in regard thereto.