Abstract

The problem of the interaction of an ultrastrong laser pulse within the framework of the quasifree state of an electron dressed by a strong laser field was studied recently. A simple and useful approximation is obtained for the multiphoton energy transfer processes which accompany the relativistic scattering of a charged particle and an effective collision frequency was found. Under this conditions the classical linear resonance is unable to explain the global absorption in laser – plasma experiments. In this paper, when the absorption rate is independence of the initial distribution function and depends only on the photon flux intensity, we show that the effective absorption coefficient is scale as Ir, where the r- parameter is in the range of 0.5 ≤ r ≤ 0.75. This scale factor is compared with the recent Brunel' expression and the results obtained from experimental conditions.