Probe-field reflection on a plasma surface driven by a strong electromagnetic field

We develop a theoretical approach to characterize the dynamics of a plasma surface irradiated by a high-intensity electromagnetic wave. The method is based on the analysis of the harmonic content in the reflection of a probe field, which is aimed at the plasma simultaneously with the strong field. In particular, a explicit formula for the angles of reflection of these harmonics is derived, showing a particular distribution directly related to the frequency of oscillation of the vacuum-plasma interface. Also, a system of equations for the reflected field amplitudes is formulated, and solved numerically in some particular cases. The experimental implementation of this scheme would provide a direct test of the so-called moving mirror models, which presently provide a basis for the understanding of the intense field-plasma interaction. (author)