Radiation damping in pulsed Gaussian beams

Abstract

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 a 0 1, it is found that the dynamics divide into three regimes. For low energy electrons (low initial γ-factor, γ 0 ) the radiation damping effects are negligible. At higher energies, but still at 2γ 0 < a 0 , the damping alters the final displacement and the net energy change of the electron. For 2γ 0 > a 0 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.

High-energy gamma-ray beams from nonlinear Thomson and Compton scattering in the ultra-intense regime

“…It has been shown that in the high intensity regime, a 0 >>1, RR can cause the electron to travel in a backwards direction during part of the laser cycle 28 when 2γ>a 0 . (In fact, at very high intensities the backwards motion can last for more than just a part of the cycle, causing the electron to become reflected and carried along in the direction of the laser pulse 7 .) The radiation emissions will be in the electron's instantaneous direction of motion, which will be continuously changing since the particle will move in a figure-of-eight orbit.…”

“…The radiation emissions from an electron in an intense field can become so strong that the resulting energy loss begins to effect the particle dynamics 7,8 . Thus we need an equation of motion that incorporates this RR effect.…”

Relativistic kinetic theory for spin-1/2 particles: Conservation laws, thermodynamics, and linear waves

“…The current model is of particular interest for strong fields. However, classical or QED corrected radiation reaction [57][58][59] is not covered and neither is strong field vacuum polarization due to QED included. Thus it is of interest to establish the regime of validity for the model, i.e.…”

Focusing effects in laser-electron Thomson scattering

“…In Fig. 15(b) we see that for weaker focussing the electrons lose so much energy that they become reflected by the laser pulse [51]. In the case of very tight focussing this is no longer the case, the reason being once again that the pulse length is significantly shortened by the focussing and so the electrons are decelerated for a shorter period of time.…”