Resonant absorption and second-harmonic generation at a rippled critical surface in a laser plasma

When a laser beam is incident on an inhomogeneous isotropic plasma, variations in density profile perpendicular to the main density gradient may develop, producing a rippling of the critical surface. We have discussed resonant absorption and second-harmonic generation at the rippled critical surface in the case of normal incidence. Analytic expressions for absorption and transformation coefficients are derived. It is possible to explain reasonably the deviation of linear theory from experimental results with this mechanism