Impact of self-focused high power beam on second harmonic generation in collisional plasmas

Abstract

Abstract In present communication, impact of self-focused high power beam on 2nd harmonic generation is explored in collisional plasmas. Non-uniform irradiance associated with Gaussian beam results in non-uniform heating of plasma electrons thereby causing focusing of main beam. There is production of strong density gradients in a direction perpendicular to input beam. The density gradients so created results in excitation of electron plasma wave (EPW) at input wave frequency. The main beam interacts with EPW leading to generation of second harmonics. With the help of WKB approximation and paraxial theory, 2nd order differential equation controlling the growth of main beam spot size is derived. Impact of laser and plasma parameters on focusing behavior of main beam and yield of second harmonics is explored through numerical simulations.