Relativistic cross-focusing of extraordinary and ordinary modes in a magnetoactive plasma

Abstract

This paper presents the effect of self-focusing on a circularly polarized beam propagating along the static magnetic field when the extraordinary and ordinary modes are present simultaneously for relativistic intensities. The nonlinearity in the dielectric function arises on account of the relativistic variation of mass, which leads to the mutual coupling of the two modes that support the selffocusing of each other. The propagation and focusing of the first mode affects the propagation and focusing of the second mode. The fact that the two modes are laser-intensity dependent leads to cross-focusing. Dynamics of one laser beam affects the dynamics of the second laser beam. When both the beams or modes are strong, the nonlinearities introduced by the relativistic effect in the presence of the magnetic field are additive in nature, such that one beam can undergo oscillatory self-focusing and other beam simultaneously defocusing and vice versa. The dynamical equation governing the cross-focusing has been set up and a numerical solution has been presented for typical relativistic laser-plasma parameters from a slightly underdense to overdense plasma.

Cross-focusing of a quadruple Gaussian laser beam in plasma in the relativistic regime

“…(13) Using equations ( 13) in (12) and equating the coefficient of r 2 on both sides of the resulting equation, one can derive the cross-focusing equations of the quadruple Gaussian laser beam in magnetoplasma in the relativistic regime as…”

“…They observed that, due to ionic thermal conduction, the extent of the cross-focusing decreases at high magnetic field values and increases at the low magnetic field values. The effect of external magnetic field on the cross-focusing of circularly polarized Gaussian laser beams when the extraordinary and ordinary modes are present simultaneously was studied by Asthana et al [12]. They found that the nonlinearity arising due to relativistic variation of the electron mass leads to the mutual coupling of the two modes, with mutual support for self-focusing.…”

Propagation of circularly polarized quadruple Gaussian laser beam in magnetoplasma

“…The radial dependence on refractive index can be expressed as ϵ(r) = [1 − Ω 2 p (r)/γ(r)]. For Ω c /γ < 1, γ can be approximated as γ = √ 1 + αAA ⋆ [25,29]. At high intensity of laser beam the externally applied magnetic field makes dielectric tensor of plasma direction dependent.…”

“…The cross-focusing of coaxial electromagnetic beams in a magnetoplasma, on account of the pondermotive force has been studied thoroughly by Sodha et al [24]. Recently Asthana et al [25] studied the relativistic cross-focusing of circularly polarized beam propagating in the direction of magnetic field with the simultaneous propagation of extraordinary and ordinary modes.…”

Self-Guidance and Self-Focusing of Rippled Electromagnetic Radiation Pulse in High Density Magnetoactive Plasma

“…Propagation of intense laser beams (Varshney et (Gupta et al 2016;Varshney et al 2013) of electromagnetic modes with in the magnetoactive plasmas been explored in the past for different types of nonlinearities. The phenomena of self-trapping and selffocusing of electromagnetic laser radiation in magnetoactive plasma has been explored when collisional nonlinearity leads on the extended period range and when ponderomotive nonlinearity leads on shorter period range (Sinha et al 1980).…”