Abstract-Terahertz radiation from multi ion plasma irradiated by two cross focused Gaussian laser beams

Physics of Plasmas

M. J. Jafari, M. R. Jafari Milani, S. Rezaei,

Critical curves: ρ0 as a function of initial beam intensity (α1E201${\alpha }_1{E}_{01}^2$) for the following parameters (a) Z1=1,Z2=2$Z_1=1,Z_2=2$ (i.e., hydrogen embedded helium plasma) and (b) n10=0.5ne0$n_{10}=0.5n_{e0}$. I and II denote the defocusing and self-focusing regions, respectively.

https://aip.scitation.org/doi/abs/10.1063/1.5115248

Terahertz (THz) radiation generation by nonlinear coupling of two color Gaussian laser beams in a plasma with multi-ion species is numerically investigated by taking into account the nonlinearity due to ponderomotive force and space-charge field. By calculating the modification of electron density distribution of such plasma, coupled differential equations governing the evolution of two laser beams' spot size and the outcome THz wave amplitude are established. The influence of the ionic species density and charge composition on the cross focusing of laser beams as well as generation of THz radiation is studied. The results mainly demonstrated that nonlinear effects in a multiply ionized plasma are excited stronger in comparison to the singly ionized one. It was found that the presence of ion species of higher charge enhances the cross focusing of beams and, consequently, THz field amplitude. The generated THz emission also strongly depends on the density of ionic species. The results showed that the minimum output of THz radiation is related to the higher density of singly charged ionic species. Moreover, it was found that the maximum value of THz amplitude takes place within a specific range of laser intensities.