Abstract
We simulated the dynamics of a formed ultrashort (femtosecond) filament in underdense plasma in the presence of a second beam. In the beginning, we demonstrated the formation of this filament in air plasma, and then we monitored its evolution at different propagation times in order to explore fundamental dynamics associated with the propagation, such as the pulse splitting and the multiple filamentations. Afterwards, we simulated the dynamics of the formed filament in the presence of a second femtosecond beam at particular input beams energy, crossing angle and different time delays. Simulation results have confirmed that reducing the time delay between the beams optimizes the properties of the formed ultrashort filament.