Propagation of non-diffracting intense ultraviolet beams

Ultraviolet pulses of 200 ps duration are focused in vacuum, and launched into the atmosphere through an aerodynamic window. Instead of diffracting, above a threshold of 100 mJ, the beam propagates in a self-induced waveguide in air. The peak electric field and beam profile are consistent with the eigenfunction of a modified nonlinear Schrödinger equation. The evolution of the beam waist with distance is calculated by a combination of the nonlinear Schrödinger equation and an equation for the nonlinear losses.