Terawatt two color filamentation in a low pressure gas: characterization by THz and X-ray generation

2-TW, 30-fs, 800-nm laser radiation and its second harmonic are used to form a filament in low pressure gas cell. This filament forms a bright source of terahertz pulses. For 1-20 mbar gas pressure we registered a hundred-fold increase of THz yield compared with ambient air conditions. The dynamics of local intensity in the filament was measured by filament foil ablation and X-ray generation techniques.