Self-Channeling of Relativistic Laser Pulses in Large-Scale Underdense Plasmas

Relativistic self-focusing and channeling of intense laser pulses have been studied in underdense plasma using 2D PIC simulations, for different laser powers and plasma densities. Analytical solutions for the stationary evacuated channels have been recovered in PIC simulations. It is shown that otherwise stable channels can accelerate electrons due to surface waves on the walls of the channels. Relativistic filaments with finite electron density are unstable to transverse modulations which lead in the nonlinear stage to the break-up of laser pulses into independent filaments. Different regimes of relativistic self-focusing and channeling, including electron heating, transverse instability and break-up of the filaments have been discussed and characterized using plasma density and laser power.