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We have investigated linear and nonlinear dynamics of ion-temperature-gradient driven drift mode for Maxwellian and non Maxwellian pair-ion plasma embedded in an inhomogeneous magnetic field having gradients in ion's temperature and number density. Linear dispersion relations are derived and analyzed analytically as well as numerically for different cases. It has been found that growth rate of instability increases with increasing eta. By using the transport equations of Braginskii, model, a set of nonlinear equations are derived. In the nonlinear regime, soliton structures are found to exist. Our numerical analysis shows that amplitude of solitary waves increases by increasing ion to electron number density ratio. These solitary structures are also found to be sensitive to non thermal kappa and Cairns distributed electrons. Our present work may contribute a good illustration of the observation of nonlinear solitary waves driven by the ITG mode in magnetically confined pair-ion plasmas and space pair-ion plasmas as the formation of localized structures along drift modes is one of the striking reasons for L-H transition in the region of improved confinements in magnetically confined devices like tokamaks., Comment: 18

Linear and nonlinear properties of obliquely propagating waves are studied in a degenerate dense cold magnetoplasma, comprising of Thomas–Fermi distributed electrons and ions as well as non-degenerate negatively charged dust particulates. By using the plane wave approximation, a linear dispersion relation for the dust-cyclotron (DC) and dust-acoustic (DA) waves is derived and analyzed numerically. For fully nonlinear waves, a Sagdeev pseudopotential theory is employed to derive an energy-balance equation and the soliton existence domain depending upon the dust concentration $(h)$ , obliqueness $(L_{z})$ , and Mach number $(M)$ . Numerical analysis reveals that the parameter $h$ enhances the domain for allowed Mach numbers, i.e., $M_{1} and therefore favoring the solitary excitations, where $M_{1}$ and $M_{2}$ are the lower and upper Mach numbers, respectively. In addition, the dust concentration significantly reduces the amplitude and the profile sharpness of the solitary pulses. Similarly, variations in the obliqueness parameter and the Mach numbers modify the wave characteristics. This paper is important for understanding the nonlinear properties of electrostatic excitations in degenerate dusty magnetoplasma, relevant to white dwarfs (WDs), namely $GD56,\,\,GD29-38,\,\,GD362$ , and $WD2115-560$ , being termed as the DUSTY DAZ WDs.

Nonlinear evolution and propagation characteristics of an ion-acoustic (IA) dipolar vortex are examined in a magnetoplasma that comprises partially degenerate electrons and dynamic ions. The adiabatic ions reduce the quantum magnetohydrodynamic equations to a modified momentum equation. The latter admits a new solution and leads to an evolution equation for the description of a coherent IA dipolar vortex. Numerical analysis reveals that variations in the relevant plasma parameters alter the evolution condition for a stable vortex. The electron exchange-correlation enhances excitation of the vortex as it extends the parametric regime associated with the stable vortex solution. On the contrary, the ion temperature lessens the nonlinear evolution of the vortex. Importantly, a degree of enhancement in the exchange-correlation potential leads to the wave dispersion and-in return-widens the vortex potential spatially. The novel nature of the derived results stresses upon the comprehension of the ordered structures in the compact stars, the magnetic mirrors, the ionosphere, the pinch devices, etc., where thermal corrections significantly impact the waves dynamics.

The properties of ion acoustic solitary and periodic structures are studied in magnetized two-ion component (O+ − H+ − e) plasmas with (r, q) distributed electrons. It is found that two modes of ion acoustic waves, namely, fast and slow modes, can propagate in such a plasma. The nonlinear Zakharov–Kuznetsov equation is derived using the well-known reductive perturbation method. Employing the theory of planar dynamical systems, the system under consideration is found to admit compressive (hump) and rarefactive (dip) solitary structures and periodic wave solutions. It is found that behavior of propagation of nonlinear ion acoustic solitary structures is different for fast and slow modes owing to the difference in physics of the two modes. The effect of the double spectral indices r and q is thoroughly explored. It is shown that altering the shape of the distribution function through these indices radically alter the propagation characteristics of nonlinear ion acoustic waves. The ratio of concentration of heavy (O+) to light ions (H+) is found to change the fast mode, whereas the temperature ratio is observed to alter the slow mode. We have applied our study to the upper ionosphere where bi-ion plasmas and the presence of non-Maxwellian electrons have been observed by various satellite missions.

Linear and nonlinear coupling of drift and ion acoustic waves are studied in a nonuniform magnetized plasma comprising of Oxygen and Hydrogen ions with nonthermal distribution of electrons. It has been observed that different ratios of ion number densities and kappa and Cairns distributed electrons significantly modify the linear dispersion characteristics of coupled drift-ion acoustic waves. In the nonlinear regime, KdV (for pure drift waves) and KP (for coupled drift-ion acoustic waves) like equations have been derived to study the nonlinear evolution of drift solitary waves in one and two dimensions. The dependence of drift solitary structures on different ratios of ion number densities and nonthermal distribution of electrons has also been explored in detail. It has been found that the ratio of the diamagnetic drift velocity to the velocity of the nonlinear structure determines the existence regimes for the drift solitary waves. The present investigation may be beneficial to understand the formation of solitons in the ionospheric F-region.

We consider a low frequency plasma comprising of Kappa distributed electrons and Maxwellian ions embedded in an external magnetic field in toroidal ion-temperature-gradient driven modes. A set of nonlinear equations are derived in the presence of equilibrium density, temperature, and magnetic field gradients. In the nonlinear regime, solutions in the form of tripolar vortices are derived by using Braginskii’s transport equations. It has been observed that the scale lengths over which the nonlinear vortex structures form get modified in the presence of Kappa distributed electrons. In tokamak the present study is applicable where non-Maxwellian population has been observed in electron cyclotron heating experiments and resonant frequency heating.

The effect of nonthermal distributions of electrons on ion-temperature-gradient (ITG)-driven drift modes in the presence of tiny dust particles for bi-ion magneto plasmas is investigated. The dynamics of bi-ions and dust particles is considered for the study of low-frequency (less than the gyrofrequencies of dust and ions) ITG mode. A new dispersion relation is derived and analyzed numerically as well as analytically. Three different distributions for nonthermal electrons (Kappa, q, and Cairns distribution) are used. It is found that the presence of nonthermal electrons in bi-ion dusty magnetoplasma reduces the growth rate of the ITG instability. These results should be useful for laboratory and space plasmas where nonthermal electrons and dust is always present.

Linear and nonlinear characteristics of electrostatic waves in a multicomponent magnetoplasma comprising of Boltzmann distributed electrons, Cairn’s distributed hot electrons, and cold dynamic ions are studied. It is found that the effect of superthermal electrons, ion-neutral collisions, and ion shear flow modifies the propagation of ion-acoustic and drift waves. The growth rate of the ion shear flow instability varies with the addition of Cairn’s distributed hot electrons. It is also investigated that the behavior of different type of vortices changes with the inclusion of superthermal hot electrons. The relevance of this investigation in space plasmas such as in auroral region and geomagnetic tail is also pointed out.

The evolution and propagation characteristics of ion-acoustic (IA) shocklets are examined in an unmagnetized collisionless plasma, comprised of warm ions and non-Maxwellian (Kappa/Cairns) electrons. Solving the fluid equations and using the frameworks of diagonalized-matrix/changing variable techniques, a nonlinear set of two characteristic wave equations is obtained, which admits dispersionless/dissipationless evolution of IA shocklets. Numerical analyses have also confirmed the excitation/deformation of IA shocklets and the wave overtaking/breaking effects at time τ > 0 for nonlinear coupling of potential field. It is found that superthermal (Kappa distributed) electrons can enhance the overtaking/breaking of IA perturbations in comparison with nonthermal Cairns distributed electrons that lead to less steepened potential field to stabilize IA excitations against the nonlinear steepening. Finite ion temperature has significant impact on the wave coupling to lead the profiles of IA shocklets ahead. This study is important to understand the physical mechanism for excitation and deformation of IA shocklets relevant to the F-region of Ionosphere.

Theoretical investigation of electrostatic ion acoustic periodic (cnoidal) waves and solitons with warm ions is presented with electrons that are assumed to follow the double spectral index distribution function. The double spectral index distribution imitates effectively the distributions that have often been seen in space plasmas. Using the standard reductive perturbation technique, the Korteweg-de Vries (KdV) equation is derived which describes the nonlinear periodic waves with appropriate boundary conditions. By using planar dynamical system to this KdV equation, the existence of solitary wave solutions and periodic wave solutions are found. It is shown that changing the electron population in regions of low and high phase space density regions alter the propagation characteristics of nonlinear ion acoustic periodic and solitary structures. Comparison of non-Maxwellian distribution functions with Maxwellian distribution is also made. The importance of the present work with regard to space plasmas is also pointed out.

Dust acoustic (DA) waves evolving into shocklets are investigated in the comet Halley plasma system relaxing to Maxwellian, Kappa, and Cairns distributions. Here, dynamics of dust is described by the fully nonlinear continuity and momentum equations. A set of two characteristic wave nonlinear equations is obtained and numerically solved to examine the DA solitary pulse that develops into oscillatory shocklets with the course of time such as at time τ = 0 , symmetric solitary pulses are formed, which develop into oscillatory shocklets. It has been observed that the variation in superthermality strongly affects the profiles of nonlinear DA structures in terms of negative potential, dust velocity, and density.

The formation and propagation of dust-acoustic (DA) solitary and rogue waves are studied in a non-relativistic degenerate Thomas-Fermi thermal dusty plasma incorporating transverse velocity perturbation effects. The electrons and ions are described by the Thomas-Fermi density distributions, whereas the dust grains are taken as dynamic and classical. By using the reductive perturbation technique, the cylindrical Kadomtsev-Petviashvili (CKP) equation is derived, which is then transformed into a Korteweg-deVries (KdV) equation by using appropriate variable transformations. The latter admits a solitary wave solution. However, when the carrier waves frequency is much smaller than the dust plasma frequency, the DA waves evolve into the nonlinear modulation instability, generating modulated wave packets in the form of Rogue waves. For the study of DA-rogue waves, the KdV equation is transformed into a self-focusing nonlinear Schrodinger equation. The variation of dust temperature and the electron density affects the nonlinearity and dispersion coefficients which suppress the amplitudes of the DA solitary and rogue waves. The present results aim to describe the nonlinear electrostatic excitations in astrophysical degenerate dense plasma.

In the present investigation, we have studied the linear and nonlinear propagation of electrostatic waves in a dense magnetoplasma with trapped electrons. Using the small amplitude approximation, formation of solitary structures has been studied both for fully and partially degenerate plasmas. The theoretical results obtained have been analyzed numerically for the parameters typically found in white dwarfs. The present work may be beneficial to understand the propagation of solitary structures with weak transverse perturbation with special reference to white dwarf asteroseismology.

Using Boltzmann-Vlasov kinetic model for nonthermal distributed electron-positron-ion plasma of our Earth’s magnetosphere and the solar wind streaming plasma can drive ion-acoustic waves unstable. It is found that the growth rate increases with the decrease of spectral index and increases with the streaming velocity of the solar wind. The numerical results are also presented by choosing some suitable parameters of magnetospheric plasma.

The effect of nonthermal electrons on ion-temperature-gradient (ITG) driven modes is investigated in the presence of variable dust charge and ion shear flow. The dust charge fluctuating expression is obtained in the presence of kappa distributed electrons. A dispersion relation is derived and analyzed numerically by choosing space plasma parameters of Jupiter/Saturn magnetospheres. It is found that the presence of nonthermal electrons population reduces the growth rate of ITG mode driven instability. The effects of ion temperature, electron density and magnetic field variation on the growth rate of ITG instability are presented numerically. It is also pointed out that the present results will be useful to understand the ITG driven modes with variable dust charge and kappa distributed electrons, present in most of the space plasma environments.

Electron temperature gradient (ETG) driven solitons are investigated having gradients in equilibrium electron temperature and equilibrium number density and with electron shear flow. In a linear regime, using model equations, a linear dispersion relation has been analysed analytically as well as numerically. ηe and electron to ion temperature ratio effects, real frequency, and growth rate of ETG instability are determined. In the nonlinear regime, the Korteweg--de Vries equation for the ETG mode has been derived and analysed numerically which shows that it admits solitary wave solutions. It can also be noted that soliton amplitude is sensitive to ηe, the magnetic field, and the temperature ratio. This work may be helpful for low frequency electrostatic modes in nonuniform electron-ion plasma having gradients in density and electron temperature and also in tokamak plasma.

Employing Vlasov-Poisson model for nonthermal distributed permeating plasma consisting of electron-positron-ion plasma of our earth’s magnetosphere and the solar wind plasma with some fixed streaming velocity, can drive ion-acoustic waves unstable. The growth rates are computed with respect to the variation in spectral index of the kappa or generalized Lorentzian distribution and streaming velocity of the solar wind. It is found that the growth rate increases with the decrease of spectral index and increases with the streaming velocity of the solar wind. The numerical results are also presented by choosing some suitable parameters.

The effect of two negative ions on the Landau damping and stellar solar wind driven instability is analyzed using kinetic theory for the Lorentzian plasmas. It is investigated that the dispersion relations, damping rates and instability growths are appreciably modified in the presence of Generalized Lorentzian or kappa distributed function and additional negative ion in our plasma system. A quantitative measurement of the threshold value of the streaming velocity is also determined to estimate the condition of the growing instability.

Properties of fully nonlinear electron-acoustic solitary waves in an unmagnetized and collisionless electron-positron-ion plasma containing cold dynamical electrons, superthermal electrons and positrons obeying Cairns’ distribution have been analyzed in the stationary background of massive positive ions. A linear dispersion relation has been derived, from which it is found that even in the absence of superthermal electrons, the superthermal positron component can provide the restoring force to the cold inertial electrons to excite electron-acoustic waves. Moreover, superthermal electron and positron populations seem to enhance the electron acoustic wave phase speed. For nonlinear analysis, Korteweg-de Vries equation is obtained using the reductive perturbation technique. It is found that in the presence of positron both hump and dip type solitons appear to excite. The present work may be employed to explore and to understand the formation of electron acoustic soliton structures in the space and laboratory plasmas with nonthermal electrons and positrons.

Linear and nonlinear properties of coupled modes in a magnetized quantum plasma in the presence of electron Fermi pressure are studied in a nonuniform magnetoplasma composed of electrons, ions, and extremely massive and negatively charged immobile dust grains. Stationary solutions of the nonlinear equations that govern the dynamics of coupled modes are presented. It is found that electrostatic dipolar vortex structure can form in such a plasma. The dipolar structures in dense plasmas are observed to be formed on a much shorter scalelength by comparison with their classical counterparts. It is found that the increasing Fermi temperature shortens the scalelength over which the nonlinear coherent structures are formed. The relevance of the present investigation with regard to the dense astrophysical plasmas is also pointed out.

Properties of fully nonlinear ion-acoustic solitary waves in an unmagnetized and collisionless pair-ion (PI) plasma containing superthermal electrons obeying Cairns distribution have been analyzed. A linear biquadratic dispersion relation has been derived, which yields the fast (supersonic) and slow (subsonic) modes in a pair-ion-electron plasma with nonthermal electrons. For nonlinear analysis, Korteweg-de Vries equation is obtained using the reductive perturbation technique. It is found that in case of slow mode, both electrostatic hump and dip type structures are formed depending on the temperature difference between positively and negatively charged ions, whereas, only dip type solitary structures have been observed for fast mode. The present work may be employed to explore and to understand the formation of solitary structures in the space (especially, the Earth’s ionosphere where two distinct pair ion species (H ±) are present) and laboratory produced pair-ion plasmas with nonthermal electrons.

Nonlinear equations governing the dynamics of finite amplitude drift-acoustic-waves are derived by taking into account sheared ion flow perpendicular to the ambient magnetic field in a quantum magnetoplasma comprised of electrons, positrons, and ions. It is shown that stationary solution of the nonlinear equations can be represented in the form of a counter-rotating vortex for a particular choice of the equilibrium profile. The counter rotating vortices are, however, observed to form on very short scales i.e., of the order of ion Larmor radius ρi in quantum plasmas. It is observed that the scalelengths over which these structures form get modified in the presence of quantum statistical and Bohm potential terms as well as the positron concentration. The relevance of the present investigation with regard to dense astrophysical environments is also pointed out.

We have investigated some linear as well as nonlinear properties of ion-acoustic wave (IAW) propagation in a non-uniform two-electron-temperature magnetoplasma in the presence of ion-sheared flows. In the linear limit, new dispersion relation has been derived and analyzed in some interesting limiting cases. It is shown that ion-sheared flow can drive the IAW unstable under a certain limit.Whereas, in the nonlinear case, dipolar and vortex street type solutions can appear. It is observed that by choosing some typical parameters of Earth's auroral region, the scalelength of the nonlinear structures are significantly modified. The present investigation might be very useful to explain various types of nonlinear structure formation which has been observed in space environments where two-electron-temperature plasma exist.

The previous works on whistler waves with electron temperature anisotropy narrated the dependence on plasma parameters, however, they did not explore the reasons behind the observed differences. A comparative analysis of the whistler waves with different electron distributions has not been made to date. This paper attempts to address both these issues in detail by making a detailed comparison of the dispersion relations and growth rates of whistler waves with electron temperature anisotropy for Maxwellian, Cairns, kappa and generalized (r, q) distributions by varying the key plasma parameters for the problem under consideration. It has been found that the growth rate of whistler instability is maximum for flat-topped distribution whereas it is minimum for the Maxwellian distribution. This work not only summarizes and complements the previous work done on the whistler waves with electron temperature anisotropy but also provides a general framework to understand the linear propagation of whistler waves with electron temperature anisotropy that is applicable in all regions of space plasmas where the satellite missions have indicated their presence.The previous works on whistler waves with electron temperature anisotropy narrated the dependence on plasma parameters, however, they did not explore the reasons behind the observed differences. A comparative analysis of the whistler waves with different electron distributions has not been made to date. This paper attempts to address both these issues in detail by making a detailed comparison of the dispersion relations and growth rates of whistler waves with electron temperature anisotropy for Maxwellian, Cairns, kappa and generalized (r, q) distributions by varying the key plasma parameters for the problem under consideration. It has been found that the growth rate of whistler instability is maximum for flat-topped distribution whereas it is minimum for the Maxwellian distribution. This work not only summarizes and complements the previous work done on the whistler waves with electron temperature anisotropy but also provides a general framework to understand the linear propagation of whistler waves with...

Nonlinear structure formation in ion-temperature-gradient (ITG) driven waves is investigated in pair-ion plasma comprising ions and nonthermal electrons (kappa, Cairns). By using the transport equations of the Braginskii model, a new set of nonlinear equations are derived. A linear dispersion relation is obtained and discussed analytically as well as numerically. It is shown that the nonthermal population of electrons affects both the linear and nonlinear characteristics of the ITG mode in pair-ion plasma. This work will be useful in tokamaks and stellarators where non-Maxwellian population of electrons may exist due to resonant frequency heating, electron cyclotron heating, runaway electrons, etc.

The shear flow in dust dynamics driven waves in combination with the dust-neutral drag is studied in a plasma comprising of ions, electrons, and dust. Non-thermal population of ions is considered, which has been observed by many satellite missions. It is found that the dissipative instability produced by dust sheared flow and dust-neutral drag gets modified by the presence of nonthermal ions. It is found that the dissipative instability enhances for the Cairns distribution, whereas the kappa distribution arrests the growth of this instability. In the nonlinear regime, the formation of vortices in the system is studied. It is found that the nonthermal population of ions significantly alters these structures in comparison with their Maxwellian counterpart. The results obtained in this paper may have relevance in the planetary magnetospheres where the dust particles are present and non-Maxwellian distribution of particles have been observed by Freja and Viking satellites.

The formation and propagation of fully nonlinear dust-acoustic (DA) waves and shocks are studied in a non-Maxwellian thermal dusty plasma which is composed of Maxwellian electrons and nonthermal energetic ions with a neutralizing background of negatively charged dust grains. For this purpose, we have solved dust dynamical equations along with quasineutrality equation by using a diagonalization matrix technique. A set of two characteristic wave equations is obtained, which admits both analytical and numerical solutions. Taylor expansion in the small-amplitude limit ( Φ ≪ 1 ) leads to nonlinear effective phase and shock speeds accounting for nonthermal energetic ions. It is numerically shown that DA pulses can be developed into DA shocklets involving the negative electrostatic potential, dust fluid velocity, and dust number density. These structures are significantly influenced by the ion-nonthermality, dust thermal correction, and temporal variations. However, the amplitudes of solitary and shock waves are...

In this paper, whistler waves propagating parallel to the ambient magnetic field with electron temperature anisotropy are investigated by employing the kinetic theory of plasmas. The electron distribution function is considered to follow the Cairns distribution. The dispersion relation for the whistler waves with Cairns distribution is derived, and the condition for the onset of instability is also obtained. It is found that the Cairns distribution significantly modifies the instability condition for the growth of whistler instability. The comparison of the dispersion characteristics and the growth rate with Maxwellian distribution is also made, and it is observed that Cairns distributed electrons yield a higher growth rate in comparison to their Maxwellian counterparts. It is also shown that unlike the kappa distribution where parallel electron beta was found to play the key role, whistler instability with Cairns distributed electrons shows a greater sensitivity towards electron temperature anisotropy. It is shown that the real frequency of the whistler waves shows a greater dependence on the choice of parallel electron beta. Interestingly, it is found that a particular combination of parallel electron beta and electron temperature anisotropy is deleterious for the whistler instability.

The Rayleigh–Taylor instability is investigated in a nonuniform dense quantum magnetoplasma. For this purpose, a quantum hydrodynamical model is used for the electrons whereas the ions are assumed to be cold and classical. The dispersion relation for the Rayleigh–Taylor instability becomes modified with the quantum corrections associated with the Fermi pressure law and the quantum Bohm potential force. Numerically, it is found that the quantum speed and density gradient significantly modify the growth rate of RT instability. In a dense quantum magnetoplasma case, the linear growth rate of RT instability becomes significantly higher than its classical value and the modes are found to be highly localized. The present investigation should be useful in the studies of dense astrophysical magnetoplasmas as well as in laser-produced plasmas.

Ion acoustic shock waves (IASW's) are studied in an unmagnetized plasma consisting of electrons, positrons and adiabatically hot positive ions. This is done by deriving the Kortweg–deVries–Burger (KdVB) equation under the small amplitude perturbation expansion method. The dissipation is introduced by taking into account the kinematic viscosity among the plasma constituents. It is found that the strength of ion acoustic shock wave is maximum for spherical, intermediate for cylindrical, and minimum for planar geometry. It is observed that the positron concentration, ratio of ion to electron temperature, and the plasma kinematic viscosity significantly modifies the shock structure. Finally, it is found that the temporal evolution of the non-planar IASW's is quite different by comparison with the planar geometry. The relevance of the present study with regard to the dense astrophysical environments is also pointed out.

Cylindrical and spherical ion-acoustic solitons in electron–positron–ion plasma have been investigated. The reductive perturbation method has been used to derive a modified Korteweg-de-Vries (mKdV) equation. The numerical solutions of the mKdV equation are presented for both geometries. We found that the amplitude and width of ion-acoustic solitons decrease with an increase in positron concentration. It is also shown that adiabatically hot ions play a destructive role in the formation of solitons in both geometries.

The dust acoustic solitary waves (DASWs) in the presence of hot adiabatic dust in cylindrical and spherical geometries are investigated in an unmagnetized dusty plasma. The modified Korteweg–de Vries (mKdV) has been derived by using the reductive perturbation technique. The numerical solutions of the mKdV equation have been presented in both the geometries for hot dust plasmas. It is found that the amplitude of the dust acoustic wave (DAW) increases with the increase of dust temperature in both the geometries. However, the hot dust has more effect on DASW in spherical geometry as compared to the cylindrical case. These results might be very useful to explain the salient features of multidimensional DAWs for space and laboratory plasmas.

Electrostatic ion-temperature-gradient (ITG) driven drift waves are investigated by using Brangskii's model for the ions and Boltzmann distribution for the electrons in a dust-contaminated plasma with equilibrium density, temperature, and magnetic field gradients. Within the local approximation, we are able to recover the coupled ion-acoustic drift-waves in an inhomogeneous magnetic field and the Rudakov–Sagdeev (R–S) ITG instability in the presence of dust-charge fluctuations. It has been shown that the dust charging is always dissipative and the growth rate of various modes are damped. Furthermore, we also derive an expression for the anomalous ion-energy flux and transport coefficient in the presence of nonthermal fluctuations. The present investigation should be helpful in identifying the features of low-frequency turbulence and associated cross-field ion-energy transport in magnetically confined dust-contaminated tokamak plasmas.

The dynamics of a high density D-T fiber plasma driven by a multi cascade system (N multiple shells of finite thicknesses) has been investigated with a view to suppress Rayleigh–Taylor (R–T) instability. Our numerical results show that the plasma parameters of the D-T fiber sensitively depends upon the shell mass ratios and thicknesses. Large values of puff-thickness and mass-ratios provide stabilization against the R–T instability in the final stage of compression but adversely affect fusion conditions. Our analysis, however, suggests that optimum values of the puff-thicknesses and mass ratios are needed to achieve fusion parameters in a multi cascade liner staged Z-pinch devices. The relevance of our present investigation to ultra high magnetic fluxes, X-ray lasers as well as controlled thermonuclear fusion is also pointed out.

Nonlinear electrostatic and electromagnetic low frequency waves are studied in magnetized electron–positron–ion (EPI) plasmas. The effects of full nonlinearity and three dimensional ion motion have been taken into account. It is shown that both density dips and humps can coexist in EPI plasmas along with bell-shaped and kink-type solitons. The new results as well as several limiting cases for comparison with earlier work have been discussed, for the sake of completeness. Relevance of this work to space, astrophysical and laboratory plasmas is pointed out.

A system of nonlinear equations which governs the dynamics of low-frequency (in comparison with the ion gyrofrequency) electrostatic waves in a nonuniform electron–positron–ion (e-p-i) magnetoplasma with sheared ion flows is presented. In the linear limit, a dispersion relation is obtained that admits new instabilities of drift-waves. It is found that ion-acoustic and electrostatic drift waves can become unstable due to ion sheared flow. Furthermore, the nonlinear interactions between these finite amplitude short-wavelength waves give rise to quadrupolar vortices. The relevance of the investigation to laboratory and astrophysical plasmas is pointed out.

Localized nonlinear dust kinetic Alfven waves are investigated in a collisionless two-ion-temperature dusty plasma consisting of a negatively charged, extremely massive, cold dust fluid and ions of two different temperatures. It is found that finite amplitude density dips and humps propagating at sub-Alfvenic speed can coexist. Further, at super-Alfvenic speed, kink type solitons are also found to exist along with density humps. It has been shown that the properties of these solitary waves are significantly modified by their speed, obliqueness, the presence of second component of ions and the ratio of temperatures of the two ion species. The results of the present investigation would be useful in understanding the formation of coherent soliton structures in laboratory, space and astrophysical dusty plasma systems, such as in the planetary rings and cometary tails.

The implosion dynamics and fusion parameters of a high density θ-pinch plasma driven by a multicascade liner Z-pinch is investigated. The imploding multicascade liner Z-pinch plasma traps an axial magnetic field, compressing it to several megagauss in an extremely short time. The fast changing magnetic flux then induces an azimuthal θ-current on the fiber surface, with a rise time an order of magnitude smaller than the applied Z-pinch current. Numerical simulation shows that for optimum choice of shell thickness of the multicascade liner system, high-densities and temperatures can be realized for fibers seeded with some high-Z impurities. At peak compression the fuel densities of the order of 1026/cm3 and temperature about 10 keV can be achieved on a time scale of the order of 0.5 ns, yielding the Lawson criterion parameter nτ ≥ 1014 s/cm3 for DT-plasma.

It is found that the low-frequency ion acoustic and electrostatic drift waves can become unstable in uniform electron–ion and electron–positron–ion plasmas due to the ion shear flow. In a collisional plasma a drift-dissipative instability can also take place. In the presence of collisions the temporal behavior of nonlinear drift-dissipative mode can be represented in the form of well-known Lorenz and Stenflo type equations that admit chaotic trajectories. On the other hand, a quasi-stationary solution of the mode coupling equations can be represented in the form of monopolar vortex. The results of the present investigation can be helpful in understanding electrostatic turbulence and wave phenomena in laboratory and astrophysical plasmas.

Analytical and numerical results are presented for the slowing down of a pair of heavy test charge projectiles through a multicomponent, dust-contaminated plasma. The correlation and interference effects of two collinear and noncollinear projectiles on electrostatic potential and energy loss are studied for a Maxwellian distribution and a special class of physically reasonable size distributions. The energy loss behavior versus projectile velocity of noncollinear projectiles is also examined for various orientations. It is found that the energy loss for Maxwellian distribution (for large value of spectral index κ) is larger compared to that for generalized Lorentzian distribution. It is also observed that for smaller values of κ, the test charge projectile gains energy instead of losing. These results would be useful for the understanding of the energy loss mechanism, which might be responsible for the coagulation of dust particles in molecular clouds, in the ion-beam driven inertial confinement fusion scheme and in dust plasma crystal formation, etc.

Nonlinear equations which govern the dynamics of low-frequency (ω≪ωci), ion-temperature gradient modes in the presence of equilibrium density, temperature, magnetic field, and electrostatic potential gradients are derived. For some specific profiles of the equilibrium flow velocity, number density, temperature, and magnetic field, new type of solutions in the form of quadrupole vortices are found for a nondissipative plasma. The results can have relevance to the understanding of the salient features of anomalous ion thermal transport and coherent vortex structure formation in magnetically confined plasmas, such as in tokamaks.

The electrostatic potential and the energy loss by N × M projectiles propagating through a dusty plasma are derived within the frame work of dielectric theory for different dust parameters of interest. An interference contribution of these projectiles to the potential and energy loss is observed which depends upon the separation between them and their orientation. The dynamic dust charge produces a potential well instead of a coulombic type potential for a slowly moving test charge having small charge relaxation rate and energy is gained by the charged projectiles. However, fast charge relaxation enhances the energy loss and some peaks are also observed showing the excitation of some electrostatic modes. These results are useful to explain the coagulation of dust grains in laboratory and space plasma as well as in the field ion-beam driven ICF scheme.

Exact localized nonlinear dust kinetic Alfven waves are investigated by retaining the complete dust nonlinearity and by invoking small but finite-β effects in a collisionless plasma, whose constituents are electrons, ions and negatively charged dust grains. Sub-Alfvenic, as well as super-Alfvenic, solitary waves consisting of smooth density humps or dips are found to exist. Further, super-Alfvenic kink type solitons are also found to occur. The soliton amplitude depends upon various plasma parameters along with the soliton propagation speed. The results of the present investigation may be useful in the diagnostics of dust in magnetized plasmas and in understanding the formation of coherent soliton structures in space and laboratory plasmas.

Compressional Dust Alfvenic Shocks (CDAS) are investigated in an electron depleted dusty plasma with dust-ion collisional effects. The large amplitude CDAS are obtained after solving the coupled nonlinear equations numerically, while small amplitude CDAS are explored through the Kortweg-de Vries Burger equation. It is pointed out that the spatio-temporal scale lengths for the formation of CDAS are different than the compressional Alfvenic shocks in an electron-ion plasma. The amplitude variation of CDAS with different parameters is shown. The transition of oscillatory shocks to monotonic shocks is presented in 3-D plots with variation in collision frequency. The importance of the results to space plasma environments is also briefly discussed.

The dynamics of obliquely propagating ion-acoustic (IA) waves in the presence of ionic pressure anisotropy and electron trapping effects is studied in a dense magnetoplasma, containing degenerate relativistic trapped electrons and dynamical (classical) ions. By using the plane wave solution, a modified linear dispersion relation for IA waves is derived and analyzed with different limiting cases and various plasma parameters both analytically and numerically. For nonlinear analysis, a reductive perturbation technique is employed to obtain a Zakharov-Kuznetsov equation involving the weakly nonlinear IA excitations. It is shown that the electron thermal correction and ionic pressure anisotropy strongly modify the wave amplitudes and width attributed to weakly nonlinear IA waves. The stability criterion for stable/unstable solitary pulses is also discussed with variations of angle (β) and temperature ratio (σ). A reduction and domain splitting of unstable excitations into sub-domains with stable and unstable ...

Large-amplitude electron acoustic (EA) waves and shocklets are investigated in a two-temperature electron plasma. For this purpose, dynamical cold electrons are described by the fully nonlinear continuity and momentum equations, while superthermal (hot) inertialess electrons are described by the κ –distribution function with a neutralizing background of static positive ions. The fluid equations along with a quasineutrality equation are solved to obtain a set of two characteristic wave equations that admit analytical and numerical solutions. It is shown that variation due to hot electron superthermality and hot-to-cold electron density ratio strongly affects the profiles of nonlinear EA structures in terms of negative potential, cold electron velocity and density. In particular, at time τ = 0 , symmetric solitary pulses are formed, which develop into oscillatory shocklets with the course of time. Our results should be useful for understanding solitary excitations and associated nonstationary large-amplitud...

In a two-fluid dissipationless plasma, strong coupling of magnetic field and flow velocity introduced by the Hall term leads to the equilibrium solution characterized by the “double curl Beltrami equation.” Internal conductor plasma configuration is investigated employing the double curl Beltrami formulation. Numerical results reveal that relaxed states of plasma exhibiting ultrahigh β associated with minimum values of field-aligned current and flow can be created which are suitable for the advanced fusion concept.

It is shown that the nonlinear equation governing the dynamics of coupled dust-acoustic and dust-cyclotron waves in a magnetized dust-ion plasma can be written in the form of an energy integral. The latter is analyzed analytically as well as numerically to investigate the properties of arbitrary amplitude solitary waves. It is found both analytically as well as numerically that there exist solitary waves only with a negative potential. The implications of these results to some space and astrophysical dusty plasma systems, especially to planetary ring systems and cometary tails, are briefly discussed.

We derive a system of nonlinear equations governing the dynamics of low-frequency electrostatic waves in a magnetized pair plasma with sheared flows that is contaminated by dust grains. For some specific profiles of the equilibrium sheared flows, the nonlinear equations admit a stationary solution in the form of a tripolar vortex. The implications of our investigation to laboratory and space plasmas are discussed.

A system of nonlinear equations for low-frequency toroidal ion-temperature-gradient modes in a nonuniform magnetoplasma with sheared plasma flow is presented. For some specific profiles of the equilibrium density, the ion temperature and sheared plasma flows, the nonlinear equations admit a tripolar vortex. The numerical results show a negative potential vortex core between the lobs of a dipole-like structure which has a positive value of the potential.