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Radiation damping in pulsed Gaussian beams

We consider the effects of radiation damping on the electron dynamics in a Gaussian beam model of a laser field. For high intensities, i.e. with dimensionless intensity a0 \gg 1, it is found that the dynamics divide into three regimes. For low energy electrons (low initial γ-factor, γ0) the radiation damping effects are negligible. At higher energies, but still at 2γ0 < a0, the damping alters the final displacement and the net energy change of the electron. For 2γ0 > a0 one is in a regime of radiation reaction induced electron capture. This capture is found to be stable with respect to the spatial properties of the electron beam and results in a significant energy loss of the electrons. In this regime the plane wave model of the laser field provides a good description of the dynamics, whereas for lower energies the Gaussian beam and plane wave models differ significantly. Finally the dynamics are considered for the case of an XFEL field. It is found that the significantly lower intensities of such fields inhibits the damping effects.