arXiv subjects

A. P. Misra

Publications and source records attributed to A. P. Misra.

At least 55 records · Page 3Linked to original sources

arXiv2018

Characteristics of solitary waves in a relativistic degenerate ion beam driven magneto plasma

The nonlinear propagation of small amplitude ion acoustic solitary wave in relativistic degenerate magneto plasma in presence of ion beam is investigated in detail. The nonlinear equations describing the evolution of solitary wave in presence of relativistic non-degenerate magnetized positive ions and ion beams including magnetized degenerate relativistic electrons are derived in terms of Zakharov-Kuznetsov (Z-K) equation for such plasma systems. The ion beams which are ubiquitous ingredient in such plasma systems, are found to have a decisive role in the propagation of solitary wave in such highly dense plasma system. The conditions of wave, propagating with typical solitonic characteristics are examined and discussed in detail under suitable conditions of different physical parameter. Both subsonic and supersonic wave can propagate in such plasmas bearing different characteristics under different physical situations. A detailed analysis of waves propagating in subsonic and/or supersonic regime is carried out. The ion beam concentrations, magnetic field as well as ion beam streaming velocity is found to play a momentous role on the control of the amplitude and width of small amplitude perturbation both in weakly(or non-relativistic) and relativistic plasmas.

physics.plasm-ph↗

arXiv2017

Surface plasmon oscillations in a semi-bounded semiconductor plasma

We study the dispersion properties of surface plasmon oscillations in a semi-bounded semiconductor plasma with the effects of the Coulomb exchange force associated with the spin polarization of electrons and holes as well as the effects of the Fermi degenerate pressure and the quantum Bohm potential. Starting from a quantum hydrodynamic (QHD) model coupled to the Poisson equation, we derive the general dispersion relation for surface plasma waves. Previous results in this context are recovered. The dispersion properties of the surface waves are analyzed in some particular cases of interest and the relative influence of the quantum forces on these waves are also studied for a nano-sized GaAs semiconductor plasma. It is found that the Coulomb exchange effects significantly modify the behaviors of the surface plasmon waves. The present results are applicable to understand the propagation characteristics of surface waves in solid density plasmas.

physics.plasm-ph↗

arXiv2017

Audio signal encryption using chaotic Hénon map and lifting wavelet transforms

We propose a new audio signal encryption scheme based on the chaotic Hénon map. The scheme mainly comprises two phases: one is the preprocessing stage where the audio signal is transformed into a data by the lifting wavelet scheme and the other in which the transformed data is encrypted by chaotic data set and hyperbolic functions. Furthermore, we use dynamic keys and consider the key space size to be large enough to resist any kind of cryptographic attacks. A statistical investigation is also made to test the security and the efficiency of the proposed scheme.

cs.CR↗

arXiv2017

Amplitude modulation of three-dimensional low frequency solitary waves in a magnetized dusty superthermal plasma

The amplitude modulation of three dimensional (3D) dust ion-acoustic wave (DIAW) packets is studied in a collisionless magnetized plasma with inertial positive ions, superthermal electrons and negatively charged immobile dust grains. By using the reductive perturbation technique, a 3D-nonlinear Schrödinger (NLS) equation is derived, which governs the slow modulation of DIAW packets. The latter are found to be stable in the low-frequency $(ω<ω_c)$ regime, whereas they are unstable for $ω>ω_c$, and the modulational instability (MI) is related to the modulational obliqueness $(θ)$. Here, $ω~(ω_c)$ is the nondimensional wave (ion-cyclotron) frequency. It is shown that the superthermal parameter $κ$, the frequency $ω_c$ as well as the charged dust impurity $(0<μ<1)$ shift the MI domains around the $ω-θ$ plane, where $μ$ is the ratio of electron to ion number densities. Furthermore, it is found that the decay rate of instability is quenched by the superthermal parameter $κ$ with cut-offs at lower wave number of modulation ($K$), however, it can be higher (lower) with increasing values of $μ$ ($ω_c$) having cut-offs at higher values of $K$.

physics.plasm-ph↗

arXiv2017

Nonlinear dust-acoustic solitary waves and shocks in dusty plasmas with a pair of trapped ions

The propagation characteristics of small-amplitude dust-acoustic (DA) solitary waves (SWs) and shocks are studied in an unmagnetized dusty plasma with a pair of trapped positive and negative ions. Using the standard reductive perturbation technique with two different scaling of stretched coordinates, the evolution equations for DA SWs and shocks are derived in the forms of complex Korteweg-de Vries (KdV) and complex Burgers' equations. The effects of dust charge variation, the dust thermal pressure, and the ratios of positive to negative ion number densities as well as the free to trapped ion temperatures on the profiles of SWs and shocks are analysed and discussed.

physics.plasm-ph↗

arXiv2017

Effects of Landau damping on ion-acoustic solitary waves in a semiclassical plasma

We study the nonlinear propagation of ion-acoustic waves (IAWs) in an unmagnetized collisionless plasma with the effects of electron and ion Landau damping in the weak quantum (semiclassical) regime, i.e., when the typical ion-acoustic (IA) length scale is larger than the thermal de Broglie wavelength. Starting from a set of classical and semiclassical Vlasov equations for ions and electrons, coupled to the Poisson equation, we derive a modified (by the particle dispersion) Korteweg-de Vries (KdV) equation which governs the evolution of IAWs with the effects of wave-particle resonance. It is found that in contrast to the classical results, the nonlinear IAW speed $(λ)$ and the linear Landau damping rate $(γ)$ are no longer constants, but can vary with the wave number $(k)$ due to the quantum particle dispersion. The effects of the quantum parameter $H$ (the ratio of the plasmon energy to the thermal energy) and the electron to ion temperature ratio $(T)$ on the profiles of $λ$, $γ$ and the solitary wave amplitude are also studied. It is shown that the decay rate of the wave amplitude is reduced by the effects of $H$.

physics.plasm-ph↗

arXiv2017

Magnetohydrodynamic shocks in a dissipative quantum plasma with exchange-correlation effects

We investigate the nonlinear propagation of multidimensional magnetosonic shock waves (MSWs) in a dissipative quantum magnetoplasma. A macroscopic quantum magnetohydrodynamic (QMHD) model is used to include the quantum force associated with the Bohm potential, the pressure-like spin force, the exchange and correlation force of electrons, as well as the dissipative force due to the kinematic viscosity of ions and the magnetic diffusivity. The effects of these forces on the properties of arbitrary amplitude MSWs are examined numerically. It is found that the contribution from the exchange-correlation force appears to be dominant over those from the pressure gradient and the other similar quantum forces, and it results into a transition from monotonic to oscillatory shocks in presence of either the ion kinematic viscosity or the magnetic diffusivity.

physics.plasm-ph↗

arXiv2016

Nonlinear Landau damping of wave envelopes in a quantum plasma

The nonlinear theory of Landau damping of electrostatic wave envelopes (WEs) is revisited in a quantum electron-positron (EP) pair plasma. Starting from a Wigner-Moyal equation coupled to the Poisson equation and applying the multiple scale technique, we derive a nonlinear Schr{ö}dinger (NLS) equation which governs the evolution of electrostatic WEs. It is shown that the coefficients of the NLS equation, including the nonlocal nonlinear term, which appears due to the resonant particles having group velocity of the WEs, are significantly modified by the particle dispersion. The effects of the quantum parameter $H$ (the ratio of the plasmon energy to the thermal energy densities), associated with the particle dispersion, are examined on the Landau damping rate of carrier waves, as well as on the modulational instability of WEs. It is found that the Landau damping rate and the decay rate of the solitary wave amplitude are greatly reduced compared to their classical values $(H=0)$.

physics.plasm-ph↗

arXiv2016

Modulation and nonlinear evolution of multi-dimensional Langmuir wave envelopes in a relativistic plasma

The modulational instability (MI) and the evolution of weakly nonlinear two-dimensional (2D) Langmuir wave (LW) packets are studied in an unmagnetized collisionless plasma with weakly relativistic electron flow. By using a 2D self-consistent relativistic fluid model and employing the standard multiple-scale technique, a coupled set of Davey-Stewartson (DS)-like equations is derived which governs the slow modulation and the evolution of LW packets in relativistic plasmas. It is found that the relativistic effects favor the instability of LW envelopes in the kθ plane, where k is the wave number and θ the angle of modulation. It is also found that as the electron thermal velocity or θ increases, the growth rate of MI increases with cutoffs at higher wave numbers of modulation. Furthermore, in the nonlinear evolution of the DS-like equations, it is seen that with an effect of the relativistic flow, a Gaussian wave beam collapses in a finite time, and the collapse can be arrested when the effect of the thermal pressure or the relativistic flow is slightly relaxed. The present results may be useful to the MI and the formation of localized LW envelopes in cosmic plasmas with a relativistic flow of electrons.

physics.plasm-ph↗

arXiv2016

Elliptically polarized electromagnetic waves in a magnetized quantum electron-positron plasma with effects of exchange-correlation

The dispersion properties of elliptically polarized electromagnetic (EM) waves in a magnetized electron-positron-pair (EP-pair) plasma are studied with the effects of particle dispersion associated with the Bohm potential, the Fermi degenerate pressure, and the exchange-correlation force. Two possible modes of the extraordinary or X wave, modified by these quantum effects, are identified and their propagation characteristics are investigated numerically. It is shown that the upper-hybrid frequency, and the cutoff and resonance frequencies are no longer constants but are dispersive due to these quantum effects. It is found that the particle dispersion and the exchange-correlation force can have different dominating roles on each other depending on whether the X waves are of short or long wavelengths (in comparison with the Fermi Debye length). The present investigation should be useful for understanding the collective behaviors of EP plasma oscillations and the propagation of extraordinary waves in magnetized dense EP-pair plasmas.

physics.plasm-ph↗

arXiv2015

Nonlinear Landau damping and modulation of electrostatic waves in a nonextensive electron-positron-pair plasma

The nonlinear theory of amplitude modulation of electrostatic wave envelopes in a collisionless electron-positron (EP) pair plasma is studied by using a set of Vlasov-Poisson equations in the context of Tsallis' $q$-nonextensive statistics. In particular, the previous linear theory of Langmuir oscillations in EP plasmas [Phys. Rev. E {\bf87}, 053112 (2013)] is rectified and modified. Applying the multiple scale technique (MST), it is shown that the evolution of electrostatic wave envelopes is governed by a nonlinear Schr{ö}dinger (NLS) equation with a nonlocal nonlinear term $\propto {\cal{P}}\int|ϕ(ξ',τ)|^2dξ'ϕ/(ξ-ξ') $ [where ${\cal P}$ denotes the Cauchy principal value, $ϕ$ is the small-amplitude electrostatic (complex) potential, and $ξ$ and $τ$ are the stretched coordinates in MST] which appears due to the wave-particle resonance. It is found that a subregion $1/3<q\lesssim3/5$ of superextensivity $(q<1)$ exists where the carrier wave frequency can turn over with the group velocity going to zero and then to negative values. The effects of the nonlocal nonlinear term and the nonextensive parameter $q$ are examined on the modulational instability (MI) of wave envelopes as well as on the solitary wave solution of the NLS equation. It is found that the modulated wave packet is always unstable (nonlinear Landau damping) due to the nonlocal nonlinearity in the NLS equation. Furthermore, the effect of the nonlinear Landau damping is to slow down the amplitude of the wave envelope, and the corresponding decay rate can be faster the larger is the number of superthermal particles in pair plasmas.

physics.plasm-ph↗

arXiv2015

Landau damping of Gardner solitons in a dusty bi-ion plasma

The effects of linear Landau damping on the nonlinear propagation of dust-acoustic solitary waves (DASWs) are studied in a collisionless unmagnetized dusty plasma with two species of positive ions. The extremely massive, micron-seized, cold and negatively charged dust particles are described by fluid equations, whereas the two species of positive ions, namely the cold (heavy) and hot (light) ions are described by the kinetic Vlasov equations. Following Ott and Sudan [Phys. Fluids {\bf 12}, 2388 (1969)], and by considering lower and higher-order perturbations, the evolution of DASWs with Landau damping is shown to be governed by Korteweg-de Vries (KdV), modified KdV (mKdV) or Gardner (KdV-mKdV)-like equations. The properties of the phase velocity and the Landau damping rate of DASWs are studied for different values of the ratios of the temperatures $(σ)$ and the number densities $(μ)$ of hot and cold ions as well the cold to hot ion mass ratio $m$. The distinctive features of the decay rates of the amplitudes of the KdV, mKdV and Gardner solitons with a small effect of Landau damping are also studied in different parameter regimes. It is found that the Gardner soliton points to lower wave amplitudes than the KdV and mKdV solitons. The results may be useful for understanding the localization of solitary pulses and associated wave damping (collisionless) in laboratory and space plasmas (e.g., the F-ring of Saturn) in which the number density of free electrons is much smaller than that of ions and the heavy, micron seized dust grains are highly charged.

physics.plasm-ph↗

arXiv2015

Modulation of ion-acoustic waves in a nonextensive plasma with two-temperature electrons

We study the amplitude modulation of ion-acoustic wave (IAW) packets in an unmagnetized electron-ion plasma with two-temperature (cool and hot) electrons in the context of the Tsallis' nonextensive statistics. Using the multiple-scale technique, a nonlinear Schr{ö}dinger (NLS) equation is derived which governs the dynamics of modulated wave packets. It is shown that in nonextensive plasmas, the IAW envelope is always stable for long-wavelength modes $(k\rightarrow0)$ and unstable for short-wavelengths with $k \gtrsim1$. However, the envelope can be unstable at an intermediate scale of perturbations with $0<k<1$. Thus, the modulated IAW packets can propagate in the form of bright envelope solitons or rogons (at small- and medium scale perturbations) as well as dark envelope solitons (at large scale). The stable and unstable regions are obtained for different values of temperature and density ratios as well as the nonextensive parameters $q_c$ and $q_h$ for cool and hot electrons. It is found that the more (less) the population of superthermal cool (hot) electrons, the smaller is the growth rate of instability with cutoffs at smaller wave numbers of modulation.

physics.plasm-ph↗

arXiv2015

Dust-acoustic solitary waves and shocks in strongly coupled quantum plasmas

We investigate the propagation characteristics of electrostatic dust-acoustic (DA) solitary waves and shocks in a strongly coupled dusty plasma consisting of intertialess electrons and ions, and strongly coupled inertial charged dust particles. A generalized viscoelastic hydrodynamic model with the effects of electrostatic dust pressure associated with the strong coupling of dust particles, and a quantum hydrodynamic model with the effects of quantum forces associated with the Bohm potential and the exchange-correlation potential for electrons and ions are considered. Both the linear and weakly nonlinear theory of DA waves are studied by the derivation and analysis of dispersion relations as well as Korteweg-de Vries (KdV) and KdV-Burgers (KdVB)-like equations. It is shown that in the kinetic regime ($ωτ_m\gg1$, where $ω$ is the wave frequency and $τ_m$ is the viscoelastic relaxtation time), the amplitude of the DA solitary waves decays slowly with time with the effect of a small amount of dust viscosity. However, the DA shock-like perturbations can be excited in the hydrodynamic regime with $ωτ_m\ll1$. The analytical and numerical solutions of the KdV and KdVB equations are also presented and analyzed with the system parameters.

physics.plasm-ph↗

arXiv2015

Complex Korteweg-de Vries equation and Nonlinear dust-acoustic waves in a magnetoplasma with a pair of trapped ions

The nonlinear propagation of dust-acoustic (DA) waves in a magnetized dusty plasma with a pair of trapped ions is investigated. Starting from a set of hydrodynamic equations for massive dust fluids as well as kinetic Vlasov equations for ions, and applying the reductive perturbation technique, a Korteweg-de Vries (KdV)-like equation with a complex coefficient of nonlinearity is derived, which governs the evolution of small-amplitude DA waves in plasmas. The complex coefficient arises due to vortex-like distributions of both positive and negative ions. An analytical as well as numerical solution of the KdV equation are obtained and analyzed with the effects of external magnetic field, the dust pressure as well as different mass and temperatures of positive and negative ions.

physics.plasm-ph↗

arXiv2014

Kadomtsev-Petviashvili (KP) Burgers equation in dusty negative ion plasmas: Evolution of dust-ion acoustic shocks

We study the nonlinear propagation of dust-ion acoustic (DIA) solitary waves in an unmagnetized dusty plasma which consists of electrons, both positive and negative ions and negatively charged immobile dust grains. Starting from a set of hydrodynamic equations with the ion thermal pressures and ion kinematic viscosities included, and using a standard reductive perturbation method, the Kadomtsev-Petviashivili Burgers (KPB) equation is derived, which governs the evolution of DIA shocks. A stationary solution of the KPB equation is obtained and its properties are analysed with different plasma number densities, ion temperatures and masses. It is shown that a transition from shocks with negative potential to positive one occurs depending on the negative ion concentration in the plasma and the obliqueness of propagation of DIA waves.

physics.plasm-ph↗

arXiv2014

Multidimensional ion-acoustic solitary waves and shocks in quantum plasmas

The nonlinear theory of two-dimensional ion-acoustic (IA) solitary waves and shocks (SWS) is revisited in a dissipative quantum plasma. The effects of dispersion, caused by the charge separation of electrons and ions and the quantum force associated with the Bohm potential for degenerate electrons, as well as, the dissipation due to the ion kinematic viscosity are considered. Using the reductive perturbation technique, a Kadomtsev-Petviashvili Burgers (KPB)-type equation, which governs the evolution of small-amplitude SWS in quantum plasmas, is derived, and its different solutions are obtained and analyzed. It is shown that the KPB equation can admit either compressive or rarefactive SWS according to when $H\lessgtr2/3$, or the particle number density satisfies $n_0\gtrless 1.3\times10^{31}$ cm$^{-3}$, where $H$ is the ratio of the electron plasmon energy to the Fermi energy densities. Furthermore, the properties of large-amplitude stationary shocks are studied numerically in the case when the wave dispersion due to charge separation is negligible. It is also shown that a transition from monotonic to oscillatory shocks occurs by the effects of the quantum parameter $H$.

physics.plasm-ph↗

arXiv2014

Dust-acoustic solitary waves in a magnetized dusty plasma with nonthermal electrons and trapped ions

The nonlinear propagation of electrostatic dust-acoustic (DA) waves in a magnetized dusty plasma consisting of negatively charged mobile dusts, nonthermal fast electrons and trapped ions with vortex-like distribution is studied. Using the reductive perturbation technique, a Korteweg-de Vries (KdV)-like equation is derived which governs the dynamics of the small-amplitude solitary waves in a magnetized dusty nonthermal plasma. It is found that due to the dust thermal pressure, there exists a critical value $(β_c)$ of the nothermal parameter $β~(>1)$, denoting the percentage of energetic electrons, below which the DA solitary waves cease to propagate. The soliton solution (travelling wave) of the KdV-like equation is obtained, and is shown to be only of the rarefactive type. The properties of the solitons are analyzed numerically with the system parameters. It is also seen that the effect of the static magnetic field (which only modifies the soliton width) becomes significant when the dust gyrofrequency is smaller than one-tenth of the dust plasma frequency. Furthermore, the amplitude of the soliton is found to increase (decrease) when the ratio of the free to trapped ion temperatures $(σ)$ is positive (negative). The effects of the system parameters including the obliqueness of propagation $(l_z)$ and $σ$ on the dynamics of the DA solitons are also discussed numerically, and it is found that the soliton structures can withstand perturbations and turbulence during a considerable time. The results should be useful for understanding the nonlinear propagation of DA solitary waves in laboratory and space plasmas (e.g., Earth's magnetosphere, auroral region, heliospheric environments etc.).

physics.plasm-ph↗