Beat wave excitation of electron plasma wave by coaxial cosh-Gaussian laser beams in collisional plasma

This paper presents a scheme for beat wave excitation of an electron plasma wave (EPW) by cross-focusing of two intense cosh-Gaussian (ChG) laser beams in an under dense collisional plasma. The plasma wave is generated on account of beating of two ChG laser beams of frequencies (1) and (2). Starting from Maxwell's equations, coupled differential equations governing the evolution of spot size of laser beams with distance of propagation have been derived by using Moment theory approach in Wentzel-Kramers-Brillouin approximation. The collisional nonlinearity depends not only on the intensity of first laser beam, but also on that of second laser beam. Therefore, dynamics of first laser beam affects that of other and hence cross-focusing of the two laser beams takes place. Numerical simulations have been carried out to investigate the effect of laser as well as plasma parameters on cross-focusing of laser beams and further its effect on power of excited EPW. It has been found that decentered parameters of the two laser beams have significant effect on power of EPW.