Three regimes of growth of a Gaussian ripple on a uniform plane electromagnetic wave front in a plasma.

Starting with the scalar wave equation and relevant expressions for nonlinear dielectric constant of plasma, the propagation of a Gaussian ripple on a plane wave front of uniform intensity has been studied in the paraxial approximation. In the plane of the ripple width (along the y axis) and the ratio of the electric field intensities of the ripple and the main beam at r=0, z=0, (along the x axis) three distinct regions (for a given intensity of the main beam) can be identified which correspond to steady divergence, oscillatory divergence, and self-focusing of the ripple. The variation of the ripple width with distance of propagation has also been obtained for typical points in the three regions. © 2004 American Institute of Physics. [ABSTRACT FROM AUTHOR]