Nonmonotonic increase in laser-driven THz emissions through multiple ionization events.

Highly charged states created through multiple ionization of gases generation by intense, single- or two-color femtosecond laser pulses. A i are shown to enhance terahertz (THz) one-dimensional, nonpropagating fluid model reveals the main conversion processes up to 1017 Wem-2 laser intensities, namely, ionization-induced, we demonstrate a cyclic growth in the helium. This behavior is confirmed by Changes in the forward and backward photocurrents and plasma currentoscillations. For increasing intensities, THz signal associated with the different binding energies of argon and I direct particle-in-cell and unidirectional pulse propagation simulations. THz spectra owing to multiple ionization are discussed. [ABSTRACT FROM AUTHOR]