Dynamics of an electron driven by relativistically intense laser radiation

Abstract

The dynamics of an electron driven by a relativistically intense laser pulse is analyzed on the basis of the equation of motion with the Lorentz force in the cases of linear and circular polarizations. Laser fields with nonplane phase fronts accelerate electrons in the longitudinal direction. An electron initially at rest is found not to move along figure-eight trajectories for the linear polarization, and not to move along circular trajectories for the circular polarization.

Comment on “Dynamics of an electron driven by relativistically intense laser radiation” [Phys. Plasmas 15, 023104 (2008)]

“…2͑c͔͒ is different from Fig. 6͑c͒ of the paper written by Galkin et al 4 and u z ͓Fig. 2͑e͔͒ is a little different from Fig.…”

“…2͑e͔͒ is a little different from Fig. 6͑e͒ of the paper written by Galkin et al 4 The electron's longitudinal velocity ͑u z end ͒ after the interaction is not zero and u z end = 0.0362, which is because of the longitudinal ponderomotive force. 5 We think that is an error in Fig.…”

“…5 We think that is an error in Fig. 6͑c͒ of the paper written by Galkin et al 4 The dependence of the electron's longitudinal velocity ͑u z end ͒ after the interaction on the minimum spot size ͑b 0 ͒ is shown in Fig. 3 for linearly polarized ͑dot-dashed line͒ and circularly polarized ͑solid line͒ laser pulses, respectively.…”

“…Figure 1 shows the temporal dependences of x ͓Fig. 4 where the linearly polarized laser pulse is used. Figure 2 shows the temporal dependences of r ͓Fig.…”

“…[1][2][3] But the comparison of the electron dynamics in the cases of the linear and circular polarizations of the optical fields did not receive enough attention in previous studies. Galkin et al 4 analyzed the dynamics of an electron driven by a relativistically intense laser pulse on the basis of the equation of motion with the Lorentz force in the cases of linear and circular polarizations. They have found that laser fields with nonplane phase fronts accelerate electrons in the longitudinal direction and an electron initially at rest is found not to move along figure-eight trajectories for the linear polarization, and not to move along circular trajectories for the circular polarization.…”