  Radiation Reaction (RR) effects in the interaction of an ultra-intense laser
pulse with a thin plasma foil are investigated analytically and by
two-dimensional (2D3P) Particle-In-Cell (PIC) simulations. It is found that the
radiation reaction force leads to a significant electron cooling and to an
increased spatial bunching of both electrons and ions. A fully relativistic
kinetic equation including RR effects is discussed and it is shown that RR
leads to a contraction of the available phase space volume. The results of our
PIC simulations are in qualitative agreement with the predictions of the
kinetic theory.
