Periodic focusing of a Gaussian electromagnetic beam in magneto-plasma

In the presence of an intense gaussian electromagnetic beam, the electrons in a magneto-plasma are heated non-uniformly and their subsequent redistribution gives rise to a saturating nonlinear dielectric constant. A rigorous kinetic treatment suggests that the plasma is always in quasithermal equilibrium. Nevertheless, the energy dependence of the relaxation time is a very sensitive parameter and has various interesting features. The presence of a static magnetic field adds very much more to the asymmetrical behaviour of the two modes in the plasma. All these effects manifest themselves in the periodic focusing of the beam.