Abstract
In this paper, the self-focusing of an electromagnetic pulsed beam in a collisional plasma has been investigated in the paraxial approximation, following the formalism developed by Akhmanov. The energy balance equation for electrons, the equation expressing the equality of pressure gradient (of electrons and ions) to the force due to space charge field, and the equation for the beam width parameter f (obtained by following Akhmanov's approach) have been simultaneously solved for given initial (z=0) time profile of the pulse to obtain f as a function of xi (cz/omega r(0)(2)) and t '= t- z/V-g, where V-g is the group velocity. Both Gaussian and sine time profiles of the pulse have been investigated. (C) 2008 American Institute of Physics. [DOI:10.1063/1.2991360]