Interaction of ultrashort laser pulses at relativistic intensities with solid targets: Relativistic skin effect

We formulate the problem of the interaction of an ultrashort highly intense laser pulse with matter within the framework of the anomalous relativistic skin effect. Analytical solutions for the electron distribution function, the depth of penetration of the electromagnetic field, and the corresponding coefficient of absorption have all been found under the assumption that the radiation interacts with a uniform plasma occupying a half-space in which the ions were immobile. We propose that the interaction of ultrashort (1 psec) laser pulses with intensities >10²⁰ W/cm² with solid targets results in the generation of relativistic laboratory plasmas. These plasmas are characterized by highly directed hard-x-ray (and possibly {γ}-ray) emission and the generation of very fast relativistic electrons and highly energetic ions.