Multiple filamentation of supercritical UV laser beam in atmospheric air

Multiple filamentation of subpicosecond UV pulses with peak power up to 0.2 TW was investigated at the Ti:Sapphire/KrF GARPUN-MTW laser facility in the direct amplification scheme. Filamentation arose in the initial preamplifier stage when peak power exceeded the critical value of 0.1 GW. The filamentation pattern was well reproducible for repetitive pulses in time scales from nanoseconds to several minutes.