Laser guiding through an axially non-uniform collisional plasma channel

Abstract

This paper presents an investigation of laser guiding through an axially non-uniform collisional plasma channel formed by ionizing laser prepulse. Due to self-defocusing of the ionizing prepulse, an axial non-uniform plasma channel is formed. When delayed second laser beam propagates through such preformed plasma channel, on account of non-uniform intensity distribution of laser beam, non-uniform heating of electrons takes place. Non-uniform heating diffuses the electrons away from the axis which further enhances the plasma channel. Unbalanced diffraction and refraction phenomenon through such an axial non-uniform collisional plasma channel results into periodic beam width variation with the distance of propagation. Second order ordinary differential equations for the beam width parameter of prepulse and the guided beam have been set up by using the moment theory approach. Laser guiding upto several Rayleigh lengths has been observed.