The formation of regular structures in the surface-electron density of a th
in target impinged by intense linear-polarized laser beams is analyzed with
in the frame of classical electrodynamics. For the cases presented in this
paper, the electron dynamics introduced by the magnetic term of the Lorentz
force is shown to be the responsible for the induction of regular surface
charge-density ripples. The build up of such structures is discussed in the
light of a simple model, in which plasma collective effects are assumed ha
rmonic, and finally contrasted with the results of more elaborated particle
-in-cell calculations.