Not-so-resonant, resonant absorption

When an intense electromagnetic wave is incident obliquely on a sharply bounded overdense plasma, strong energy absorption can be accounted for by the electrons that are dragged into the vacuum and sent back into the plasma with velocities v{}vosc. This mechanism is more efficient than usual resonant absorption for v_osc/ω>L, with L being the density gradient length. In the very high-intensity CO₂-laser--target interaction, this mechanism may account for most of the energy absorption.