Investigation of THz radiation generation in a laser spark of axicon discharge

Results of experimental investigations and theoretical modeling of THz pulse generation in a laser spark of axicon discharge are presented. Experimental results demonstrate define evidence of Cherenkov cone in radiation pattern of THz radiation, what is in favor of the idea that radiation is generated in the region of ionization front, moving with superlight velocity. Polarization features in generated radiation and weak reaction to the applied external dc electric field give rise to the idea that THz radiation is generated due to internal low frequency electric field excited in the process of laser discharge. The main discrepancy between theoretical expectations and experimental results is a rather low frequency of generated THz radiation which means low ionization rate of ambient air in the generation region and is a matter of theoretical simulations.