Influence of a self-focused cosh-Gaussian laser beam on the excitation of an ion-acoustic wave in a collisionless plasma

This study presents an analytical and numerical study of the excitation of ion-acoustic waves in laser–plasma interaction. The ion-acoustic wave is excited by a cosh-Gaussian laser beam in an unmagnetized collisionless plasma. The impact of self-focusing of the cosh-Gaussian laser on the excitation of the ion-acoustic wave has been studied. Nonlinear differential equations for the beam width parameters of the cosh-Gaussian laser beam and ion-acoustic wave have been established with the help of the paraxial-ray and Wentzel–Kramers–Brillouin approximations, where relativistic and ponderomotive nonlinearities are functional simultaneously. The influence of the laser decentered parameter, relative plasma density, and incident laser intensity on the self-focusing/intensity of a cosh-Gaussian laser beam and ion-acoustic wave has been investigated for specific laser and plasma parameters. The results have also been compared with relativistic nonlinearity and a Gaussian profile of the laser beam. The findings highlight the significant influence of the self-focusing of the cosh-Gaussian laser beam on the amplitude of the ion-acoustic wave.