Relativistic propagation of Hermite-Gaussian laser beams in plasma with density transition

Abstract

Propagation of Hermite-Gaussian laser beam in a collision-less plasma with density transition has been investigated by taking in to account the relativistic effect. The differential equation for beam width parameter is obtained by using paraxial approach. The spot size of the laser beam decreases as the beam penetrates deeper in to the plasma due to the role of a plasma density ramp. Since the laser beam shows an oscillatory self-focusing and defocusing behavior with the propagation distance. The density ramp could be important for the self-focusing of a high-power laser by choosing the suitable laser and plasma parameters. To reduce the defocusing, localized upward plasma density ramp is introduced, so that an earlier and stronger self-focusing is obtained.