Fig. 1. THz wave measurement system generated by double beam plasma

Fig. 2. (a) Schematic diagram of the relative position of the two plasma filaments; (b) Two plasma filaments during the experiment (graphics obtained by CCD camera)

Fig. 3. THz wave radiation decreases when the double beam plasma coincides

Fig. 4. (a) THz wave absorption varies with the plasma power at 800 nm for different plasma wavelengths; (b) THz wave absorption varies with the plasma wavelength

Fig. 5. (a) Calculated terahertz absorption intensity as a function of the 800 nm plasma power; (b) Comparison between the simulated and experimental results of the terahertz absorption intensity as a function of plasma wavelength

Fig. 6. THz wave radiation intensity changes obtained in different gas environments (the black solid line is the result obtained in an argon atmosphere, and the red solid line is the experimental result obtained in a nitrogen environment)

Fig. 7. Reduced amplitude of THz waves in different gas environments