Tarsem Singh Gill

Modulational instability of ion-acoustic waves in a plasma with a q-nonextensive electron velocity distribution

The modulational instability (MI) of ion-acoustic waves (IAWs) in a two-component plasma is investigated in the context of the nonextensive statistics proposed by Tsallis [J. Stat. Phys. 52, 479 (1988)]. Using the reductive perturbation method, the nonlinear Schrodinger equation (NLSE) which governs the MI of the IAWs is obtained. The presence of the nonextensive electron distribution is shown to influence the MI of the waves. Three different ranges of the nonextensive q-parameter are considered and in each case the MI sets in under different conditions. Furthermore, the effects of the q-parameter on the growth rate of MI are discussed in detail.

Self-focusing of cosh-Gaussian laser beam in a plasma with weakly relativistic and ponderomotive regime

This paper presents an investigation of the self-focusing of cosh-Gaussian laser beam in a plasma with linear absorption taking into account the combined effects of relativistic and ponderomotive type nonlinearities. Nonlinear parabolic partial differential equation governing the evolution of complex envelope in slowly varying envelope approximation is solved using variational approach. Self-focusing and self-phase modulation as well as self-trapping of cosh-Gaussian beam are studied at various values of decentered parameter b, with different absorption levels ki′. Numerical analysis shows that these parameters play vital role on propagation characteristics.

Self-focusing and self-phase modulation of an elliptic Gaussian laser beam in collisionless magnetoplasma

The problem of nonlinear self-focusing of elliptic Gaussian laser beam in collisionless magnetized plasma is studied using variation approach. The dynamics of the combined effects of nonlinearity and spatial diffraction is presented. With a and b as the beam width parameters of the beam along x and y directions, respectively, the phenomenon of cross-focusing is observed where focusing of a results in defocusing of b and vice versa. Although no stationary self-trapping is observed, oscillatory self-trapping occurs far below the threshold. The regularized phase is always negative.

Ion-acoustic solitons in a plasma consisting of positive and negative ions with nonisothermal electrons

In this research paper, the authors study the propagation of ion-acoustic solitons in a plasma consisting of warm positive and negative ions with different concentration of masses, charged states, and nonisothermal electrons. To account for the full nonlinearity of plasma equations, a quasipotential method is used here. The potential so obtained is characterized for solitons as a function of Mach number, positive and negative ions temperature, nonisothermal electrons, different concentration of negative and positive ions over a wide range of parameter space. Corresponding to isothermal case with β=1, coexistence of compressive and rarefactive solitons is obtained. For non-negative β≠1, only compressive solitons are observed. The prediction, that with introduction of negative ions there exists a critical ion concentration below which compressive solitons exist and above which rarefactive solitons exist, is ruled out for nonisothermal electrons.

Modulational instability of dust acoustic solitons in multicomponent plasma with kappa-distributed electrons and ions

In the present investigation the modulational instability (MI) of dust acoustic wave (DAW) in four-component dusty plasma consisting of negative and positive charged dust grains and kappa (κ) distributed electrons and ions is studied. Considering the multifluid plasma model and using the reductive perturbation technique, nonlinear Schrodinger equation, which governs the MI of DAW, is obtained. It is found that presence of positive dust component, kappa-distributed electrons (κe), ions (κi), and temperature ratio (σ) significantly modify the domain of the MI and localized envelope excitations. Further, the effects of these parameters on the growth rate of MI have also been discussed in detail.

A nonlinear Zakharov-Kuznetsov equation in magnetized plasma with q-nonextensive electrons velocity distribution

By using the reductive perturbation method (RPM), a nonlinear Zakharov-Kuznetsov (ZK) equation for ion-acoustic solitary waves (IASWs) is derived for a magnetized plasma in which the electrons are nonextensively distributed. The combined effects of electron nonextensivity, strength of magnetic field, and obliqueness on the ion acoustic (IA) solitary profile are analyzed. Three different ranges of the nonextensive q-parameter are considered. It is observed that the system may support both compressive as well as rarefactive solitons. The magnetic field has no effect on the amplitude of solitary waves whereas the obliqueness affects both the amplitude as well as the width of the solitary wave structures.

Relativistic self-focusing and self-phase modulation of cosh-Gaussian laser beam in magnetoplasma

In this paper, we have investigated the propagation characteristics of cosh-Gaussian laser beam in magnetoplasma using relativistic nonlinearity. The field distribution in the medium is expressed in terms of beam width parameter a n and decentred parameter b . An appropriate nonlinear Schraodinger equation has been solved analytically using variational approach. The behaviour of beam width parameter with dimensionless distance of propagation ξ for various b values is examined. Self-phase modulation and self-trapping is also studied under variety of parameters. Further, the effect of magnetic field on self-focusing of the beam have been explored.

Relativistic and ponderomotive effects on evolution of laser beam in a non-uniform plasma channel

The nonlinear parabolic partial differential equation governing the evolution of the complex envelope in the slowly varying envelope approximation is solved using the variational approach. The basic nonlinear phenomena of relativistic and ponderomotive self-focusing in a plasma channel are taken into account. Self-focusing, self-phase modulation as well as self-trapping of laser beam is studied in a variety of situations. Further, in the absence of dissipation mechanisms, the stability of the beam is also studied.

Higher order solutions to ion-acoustic solitons in a weakly relativistic two-fluid plasma

The nonlinear wave structure of small amplitude ion-acoustic solitary waves (IASs) is investigated in a two-fluid plasma consisting of weakly relativistic streaming ions and electrons. Using the reductive perturbation theory, the basic set of governing equations is reduced to the Korteweg–de Vries (KdV) equation for the lowest order perturbation. This analysis is further extended using the renormalization technique for the inclusion of higher order nonlinear and dispersive effects for better accuracy. The effect of higher order correction and various parameters on the soliton characteristics is investigated and also discussed.

Ion acoustic soliton in weakly relativistic magnetized electron–positron–ion plasma

A theoretical investigation was made for the ion acoustic wave in a weakly relativistic magnetized electron-positron-ion warm plasma. A Korteweg-de vries equation (KdV) is derived by using a standard reductive perturbation method. It is found that the presence of ion temperature (σ), ratios of positron-to-electron density (β), electron-to-positron temperature (α), and relativistic factor (Ur) significantly modify solitonic behavior. The authors observed that these parameters considerably change the amplitude and width of the solitary wave.