Self-Focusing of Quadruple Gaussian Laser Beam in an Inhomogenous Magnetized Plasma with Ponderomotive Non-Linearity:Effect of Linear Absorption

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.

Quadruple Gaussian Laser Beam Profile Dynamics in Collisionless Magnetized Plasma

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.

Relativistic Self-Focusing of Hermite-cosh-Gaussian Laser Beam in Magnetoplasma with Exponential Plasma Density Ramp

In the present manuscript,we analyse the effect of exponential plasma density ramp for relativistic selffocusing of Hermite-cosh-Gaussian laser pulse in magnetoplasma.The exponential plasma density ramp is found to be more prominent in achieving the stronger self-focusing of Hermite-cosh-Gaussian laser beam in comparison to the tangential plasma density ramp.We propose a theoretical model for propagation of Hermite-cosh-Gaussian laser pulse in magnetoplasma with exponential density ramp.The nonlinearity in the medium arises because of the relativistic motion of electrons,being responsible for relativistic self-focusing.Equation of the beam width parameter is set up by taking the expression for the dielectric function and following Wentzel-Kramers-Brillouin(WKB)with paraxial ray approximations for mode indices m=0,1 and 2.Effect of decentered parameter is also analysed,which results in stronger self-focusing of the Hermite-cosh-Gaussian laser beam.Stronger self-focusing of laser beam is more pronounced in high density plasma with higher magnetic field.