Filamentation patterns of TW laser pulses in air

We simulate filamentation patterns produced by the TERAMOBILE laser, which delivers pulses of 300 fs duration with 300-mJ energy at the wavelength /spl lambda//sub 0/ = 800 nm. The beam, launched in the atmosphere in parallel geometry, breaks up into multiple filaments, which are observed from a white screen at different propagation distances up to 100 m. Filaments first take place from the intensity fluctuations of the ring-like beam diffraction pattern at the distance z = 15 m. They are next randomly nucleated along this ring before secondary filaments occur near the optical axis.