The propagation of quadruple Gaussian laser beam in a plasma characterized by axial inhomogeneity and nonlinearity due to ponderomotive force in the paraxial ray approximation is investigated.An appropriate expression...The propagation of quadruple Gaussian laser beam in a plasma characterized by axial inhomogeneity and nonlinearity due to ponderomotive force in the paraxial ray approximation is investigated.An appropriate expression for the nonlinear dielectric constant has been developed in the presence of external magnetic field,with linear absorption and due to saturation effects for arbitrary large intensity.The effects of different types of plasma axial inhomogeneities on self-focusing of laser beam have been studied with the typical laser and plasma parameters.Self-focusing of quadruple Gaussian laser beam in the presence of externally applied magnetic field and saturating parameter is found significantly improved in the case of extraordinary mode.Our results reveal that initially converging beam shows oscillatory convergence whereas initially diverging beam shows oscillatory divergence.The beam is more focussed at lower intensity in both cases viz.extraordinary and ordinary mode.展开更多
Obliquely propagating electron acoustic shock waves in magnetized plasma composed of stationary ions, cold and non-extensive hot electrons are investigated by deriving Korteweg–de Vries Burgers(KdVB) equation. The ta...Obliquely propagating electron acoustic shock waves in magnetized plasma composed of stationary ions, cold and non-extensive hot electrons are investigated by deriving Korteweg–de Vries Burgers(KdVB) equation. The tangent hyperbolic method is used to solve the KdVB equation in dissipative medium. The dissipation effect is introduced in the model by means of kinematic viscosity term. The analytical calculations of the KdVB equation shows that the structures(amplitude, velocity and width) of the shock waves are modified significantly with kinematic viscosity(η_0), obliqueness(k_z) and magnetic field(ω_c). Since plasmas are ubiquitously permeated with magnetic field, it is pertinent to explore the characteristics of KdVB equation in a magnetized plasmas.展开更多
This paper presents an investigation of self-focusing of a quadruple Gaussian laser beam in collisionless magnetized plasma.The nonlinearity due to ponderomotive force which arises on account of nonuniform intensity d...This paper presents an investigation of self-focusing of a quadruple Gaussian laser beam in collisionless magnetized plasma.The nonlinearity due to ponderomotive force which arises on account of nonuniform intensity distribution of the laser beam is considered.The nonlinear partial differential equation governing the evaluation of complex envelope in the slowly varying envelope approximation is solved using a paraxial formalism.The self-focusing mechanism in magnetized plasma,in the presence of self-compression mechanism will be analyzed in contrast to the case in which it is absent.It can be observed that,in case of ponderomotive nonlinearity,the self-compression mechanism obstructs the pulse self-focusing above a certain intensity value.The effect of an external magnetic field is to generate pulses with smaller spot size and shorter compression length.The lateral separation parameter and the initial intensity of the laser beam play a crucial role on focusing and compression parameters.Also,the three-dimensional analysis of pulse propagation is presented by coupling the self-focusing equation with the self-compression one.展开更多
文摘The propagation of quadruple Gaussian laser beam in a plasma characterized by axial inhomogeneity and nonlinearity due to ponderomotive force in the paraxial ray approximation is investigated.An appropriate expression for the nonlinear dielectric constant has been developed in the presence of external magnetic field,with linear absorption and due to saturation effects for arbitrary large intensity.The effects of different types of plasma axial inhomogeneities on self-focusing of laser beam have been studied with the typical laser and plasma parameters.Self-focusing of quadruple Gaussian laser beam in the presence of externally applied magnetic field and saturating parameter is found significantly improved in the case of extraordinary mode.Our results reveal that initially converging beam shows oscillatory convergence whereas initially diverging beam shows oscillatory divergence.The beam is more focussed at lower intensity in both cases viz.extraordinary and ordinary mode.
基金Punjab Technical University, Kapurthala (India) for their support
文摘Obliquely propagating electron acoustic shock waves in magnetized plasma composed of stationary ions, cold and non-extensive hot electrons are investigated by deriving Korteweg–de Vries Burgers(KdVB) equation. The tangent hyperbolic method is used to solve the KdVB equation in dissipative medium. The dissipation effect is introduced in the model by means of kinematic viscosity term. The analytical calculations of the KdVB equation shows that the structures(amplitude, velocity and width) of the shock waves are modified significantly with kinematic viscosity(η_0), obliqueness(k_z) and magnetic field(ω_c). Since plasmas are ubiquitously permeated with magnetic field, it is pertinent to explore the characteristics of KdVB equation in a magnetized plasmas.
文摘This paper presents an investigation of self-focusing of a quadruple Gaussian laser beam in collisionless magnetized plasma.The nonlinearity due to ponderomotive force which arises on account of nonuniform intensity distribution of the laser beam is considered.The nonlinear partial differential equation governing the evaluation of complex envelope in the slowly varying envelope approximation is solved using a paraxial formalism.The self-focusing mechanism in magnetized plasma,in the presence of self-compression mechanism will be analyzed in contrast to the case in which it is absent.It can be observed that,in case of ponderomotive nonlinearity,the self-compression mechanism obstructs the pulse self-focusing above a certain intensity value.The effect of an external magnetic field is to generate pulses with smaller spot size and shorter compression length.The lateral separation parameter and the initial intensity of the laser beam play a crucial role on focusing and compression parameters.Also,the three-dimensional analysis of pulse propagation is presented by coupling the self-focusing equation with the self-compression one.
