Strong Terahertz Generation by Beating of Two Super Gaussian Laser Beams in Axially Magnetized Plasma

THz generation by nonlinear mixing of two coaxial Super-Gaussian laser beams, propagating in rippled density plasma with an axially applied static magnetic field, is investigated. The ponderomotive force which arises due to nonuniform spatial intensity profiles of laser beams, imparts a nonlinear oscillatory velocity at beat wave frequency to electrons. This oscillatory velocity couples with the preformed density ripple to generate a nonlinear current density driving a radiation. Frequencies of lasers are chosen such that the beat frequency lies in the terahertz region. The density ripple provides the phase matching for resonant excitation and the axial static magnetic field is utilized to enhance the nonlinear coupling. Numerical results show that the yield of the generated THz amplitude enhances with increase in index of super-Gaussian lasers as well as the magnitude of the axially applied static magnetic field.