Guiding of a laser beam in a collisionless magnetoplasma channel

Abstract

We present an investigation of laser guiding through an axially nonuniform collisionless magnetoplasma channel formed by the ionizing laser prepulse. With the propagation of a guided laser beam through such a preformed plasma channel, a ponderomotive force on account of the nonuniform intensity distribution of the laser beam comes into play, which further enhances the plasma channel. Unbalanced diffraction and refraction phenomena through such an axially nonuniform collisionless magnetoplasma channel results in alternate convergence and divergence of the laser beam. Wave equations governing the propagation characteristics of the ionizing prepulse and delayed pulse through an axialy nonuniform collisionless magnetoplasma channel have been solved by the moment theory approach. The effect of the magnetic field and intensity of a guided beam has been seen on the propagation of the second guided beam in the plasma channel. It is observed that there is an increase in the propagation of a guided beam with the increase in the magnetic field and intensity of the guided beam. This observation is very useful for the fast-ignitor concept, where the guided laser pulse is propagated through the plasma region without any absorption up to several Rayleigh lengths.