The generation of terahertz (THz) radiation through two-color laser-induced plasma filamentation in air has been extensively investigated due to the broadband and relatively high yield of the THz radiation. The angular distribution of the generated THz radiation has a distinct dip along the propagation axis, which limits the applications of the THz radiation. Here, we employ an interference model of electric-field elements with an asymmetric current pulse to investigate the cone angle dependency on the electron temperature and laser pulse duration. The leading edge ${\tau }_1$ and the trailing edge ${\tau }_2$ of this asymmetric current pulse play significant roles, which are determined by the laser duration and electron collision, respectively. With this model, our simulations obtain the THz cone angles agreeing with the ones observed in previous experiments. We also find that the THz intensity increases with ${\tau }_1$ and decays with ${\tau }_2$. The THz cone angle first increases and then decreases with the growth of ${\tau }_2$. Particularly, the electron temperature affects the ${\tau }_2$, which could provide a potential diagnostic method to determine electron temperature by measuring THz angular distribution.

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• Atomic & molecular collisions
• Laser-plasma interactions
• Plasma ionization
• Terahertz generation in plasmas