Relativistic theory of inverse-bremsstrahlung absorption of ultrastrong laser radiation in plasma

The nonlinear absorption of laser radiation of relativistic intensities in a plasma by a mechanism of stimulated bremsstrahlung of electrons on the ions/nuclei is investigated in the low-frequency approximation. A nonlinear inverse-bremsstrahlung absorption coefficient is studied for intermediate, as well as at asymptotically large values of laser fields and high temperatures of electrons. (paper)