1,128 research outputs found
Electron-acoustic solitary pulses and double layers in multi-component plasmas
We consider the nonlinear propagation of finite amplitude electron-acoustic
waves (EAWs) in multi-component plasmas composed of two distinct groups of
electrons (cold and hot components), and non-isothermal ions. We use the
continuity and momentum equations for cold inertial electrons, Boltzmann law
for inertialess hot electrons, non-isothermal density distribution for hot
ions, and Poisson's equation to derive an energy integral with a modified
Sagdeev potential (MSP) for nonlinear EAWs. The MSP is analyzed to demonstrate
the existence of arbitrary amplitude EA solitary pulses (EASPs) and EA double
layers (EA-DLs). Small amplitude limits have also been considered and
analytical results for EASPs and EA-DLs are presented. The implication of our
results to space and laboratory plasmas is briely discussed
Dust-acoustic rogue waves in an opposite polarity dusty plasma featuring non-extensive statistics
Modulational instability (MI) of dust acoustic waves (DAWs), which propagates
in an opposite polarity dusty plasma system, containing inertial warm
negatively and positively charged dust particles as well as non-extensive
q-distributed elec- trons and ions, has been theoretically investigated. The
nonlinear Schrodinger (NLS) equation is derived by employing the reductive
perturbation method. The NLS equation leads to the MI of DAWs as well as to the
formation of DAW rogue waves (DARWs), which are formed due to the effects of
nonlinearity in the propagation of DAWs. Both stable and unstable regions are
revealed from the analysis of the NLS equation. It is observed that the basic
features of the DAWs (viz. stability of the wave profile, MI growth rate,
amplitude, and width of DARWs) are significantly modified by the various plasma
parameters such as non-extensive parameter, electron number density, and
electron temperature. The existence of the non-extensive electron/ion
distribution creates an influence on the MI of the waves. It is observed that
non-extensive distributed ions have more effect on the MI of the DAWs than
electrons.Comment: 13 pages; 8 figure
Electrostatic rogue waves in double pair plasmas
A nonlinear Schr\"{o}dinger equation is derived to investigate the
modulational instability (MI) of ion-acoustic (IA) waves (IAWs) in a double
pair plasma system containing adiabatic positive and negative ion fluids along
with super-thermal electrons and positrons. The analytical analysis predicts
two types of modes, viz. fast () and slow () IA modes. The
possible stable and unstable parametric regions for the IAWs in presence of
external perturbation can be observed for both and . The
number density of the negative ions and positrons play a vital role in
generating the IA rogue waves (IARWs) in the modulationally unstable region.
The applications of our present work in astrophysical environments [viz.
D-region () and F-region () of the Earth's
ionosphere] as well as in laboratory plasmas [viz. pair-ion Fullerene ()] are pinpointed.Comment: 5 pages; 6 figure
Self-gravitating envelope solitons in a degenerate quantum plasma system
The existence and the basic features of ion-acoustic (IA) envelope solitons
in a self-gravitating degenerate quantum plasma system (SG-DQPS), containing
inertial non-relativistically degenerate light and heavy ion species as well as
inertialess non-relativistically degenerate positron and electron species, have
been theoretically investigated by deriving the nonlinear Schr\"{o}dinger (NLS)
equation. The NLS equation, which governs the dynamics of the IA waves, has
disclosed the modulationally stable and unstable regions for the IA waves. The
unstable region allows to generate bright envelope solitons which are
modulationaly stable. It is found that the stability and the growth rate
dependent on the plasma parameters (like, mass and number density of the plasma
species). The implications of our results in astronomical compact object (viz.
white dwarfs, neutron stars, and black holes, etc.) are briefly discussed.Comment: 6 figures,6 page
Rogue waves in multi-pair plasma medium
The nonlinear propagation of ion-acoustic (IA) waves (IAWs), which are
governed by the nonlinear Schr\"{o}dinger equation (NLSE), in multi-pair
plasmas (MPPs) containing adiabatic positive and negative ion fluids as well as
non-extensive (-distributed) electrons and positrons, is theoretically
investigated. It is observed that the MPP under consideration supports two
types of modes (namely, fast and slow IA modes), and the modulationally stable
and unstable parametric regimes for the fast and slow IA modes are determined
by the sign of the ratio of the dispersive coefficient to the nonlinear one. It
is also found that the modulationally unstable regime generates highly
energetic IA rogue waves (IARWs), and the amplitude as well as the width of the
IARWs decrease with increase in the value of (for both and
limits). These new striking features of the IARWs are found to be applicable in
the space [viz. D-region () and F-region () of
the Earth's ionosphere] and laboratory MPPs [viz. fullerene ()].Comment: 8 figures, 5 page
Self-gravitating envelope solitons in astrophysical compact objects
The propagation of ion-acoustic waves (IAWs) in a collisionless unmagnetized
self-gravitating degenerate quantum plasma system (SG-DQPS) has been studied
theoretically for the first time. A nonlinear Schr\"{o}dinger equation is
derived by using the reductive perturbation method to study the nonlinear
dynamics of the IAWs in the SG-DQPS. It is found that for ()
(where is critical value of the propagation constant which determines
the stable and unstable region of IAWs) the IAWs are modulationally unstable
(stable), and that depends only on the ratio of the electron number
density to light ion number density. It is also observed that the
self-gravitating bright envelope solitons are modulationally stable. The
results obtained from our present investigation are useful for understanding
the nonlinear propagation of the IAWs in astrophysical compact objects like
white dwarfs and neutron stars.Comment: 6 figure
Dust-acoustic rogue waves in four component plasmas
A theoretical investigation has been made on modulational instability (MI)
and dust-acoustic (DA) rogue waves (DARWs) in a four dusty plasma medium
containing inertial negatively charged massive heavy (light) cold (hot) dust
grains as well as super-thermal electrons and non-thermal ions. The reductive
perturbation method is used to derive the nonlinear Schr\"{o}dinger equation,
and two types of modes, namely fast and slow DA modes, have been observed. The
conditions for the MI and the formation of associated DARWs are found to be
significantly modified by the effects of non-thermality of ions (),
super-thermality of electrons (), density-ratio of non-thermal ion to
cold dust (), and mass-ratio of cold dust to hot dust (), etc.
The implications of our current investigation in space and laboratory plasmas
are briefly discussed.Comment: 5 figures; 5 page
Dust-acoustic envelope solitons in super-thermal plasmas
The modulational instability (MI) of the dust-acoustic waves (DAWs) in an
electron-positron-ion-dust plasma (containing super-thermal electrons,
positrons and ions along with negatively charged adiabatic dust grains) is
investigated by the analysis of the nonlinear Schr\"{o}dinger equation (NLSE).
To derive the NLSE, the reductive perturbation method has been employed. Two
different parametric regions for stable and unstable DAWs are observed. The
presence of super-thermal electrons, positrons and ions significantly modifies
both the stable and unstable regions. The critical wave number (at which
modulational instability sets in) depends on the super-thermal electron,
positron, and ion, and adiabatic dust concentrations.Comment: 11 pages; 8 figure
Modulational instability and ion-acoustic envelope solitons in four component plasmas
Modulational instability (MI) of ion-acoustic waves (IAWs) has been
theoretically investigated in a plasma system which is composed of inertial
warm adiabatic ions, isothermal positrons, and two temperature superthermal
electrons. A nonlinear Schr\"odinger (NLS) equation is derived by using
reductive perturbation method that governs the MI of the IAWs. The numerical
analysis of the solution of NLS equation shows the existence of both stable
(dark envelope solitons exist) and unstable (bright envelope solitons exist)
regimes of IAWs. It is observed that the basic features (viz. stability of the
wave profile and MI growth rate) of the IAWs are significantly modified by the
superthermal parameter () and related plasma parameters. The results of
our present investigation should be useful for understanding different
nonlinear phenomena in both space and laboratory plasmas.Comment: Submitted to Physics of plasma
Envelope solitons in double pair plasmas
A double pair plasma system containing cold inertial positive and negative
ions, and inertialess super-thermal electrons and positrons is considered. The
standard nonlinear Schr\"{o}dinger equation is derived by using the reductive
perturbation method to investigate the nonlinear dynamics of the ion-acoustic
waves (IAWs) as well as their modulation instability. It is observed that the
ion-acoustic dark (bright) envelope solitons are formed for modulationally
stable (unstable) plasma region, and that the presence of highly dense
super-thermal electrons and positrons enhances (reduces) this unstable (stable)
region. It is also found that the effect of super-thermality of electron or
positron species causes to increase the nonlinearity, and to fasten the
formation of the bright envelope solitons. These results are applicable to both
space and laboratory plasma systems for understanding the propagation of
localized electrostatic disturbances.Comment: 7 figures, 10 page
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