PIC simulations of high-power THz radiation produced by the collision of profiled plasma wakefields

Abstract

A PIC model allowing to study generation of THz radiation by the collision of plasma wakes with mismatching small-scale transverse modulation of electrostatic potential are presented in the paper. We discuss the scheme in which each of the profiled wakes is excited by a pair of interfering femtosecond laser pulses copropagating at a small angle to each other. The interference of laser fields produces transverse modulation of the ponderomotive force on plasma electrons resulting in production of wakefields with the small-scale nonuniform structure. In this paper, we generalize the model of virtual laser pulses allowing not to resolve the laser wavelenghth in order to take into account the effects of laser interference and then implement this model in a 2D3V PIC code in slab geometry. By modeling the collision of plasma wakes slightly shifted in the transverse direction, we show that the power of the produced THz radiation increases with the growth of the laser spot-size, which makes the scheme applicable to most powerful and energetic laser systems and opens the way to generation of gigawatt-level THz pulses.