The interaction of free electrons with intense laser beams in vacuum is studied using a 3D test particle simulation model that solves the relativistic Newton-Lorentz equations of motion in analytically specified laser fields. Recently, a group of solutions was found for very intense laser fields that show interesting and unusual characteristics. In particular, it was found that an electron can be captured within the high-intensity laser region, rather than expelled from it, and the captured electron can be accelerated to GeV energies with acceleration gradients on the order of tens of GeV/cm. This phenomenon is termed the capture and acceleration scenario (CAS) and is studied in detail in this paper. The maximum net energy exchange by the CAS mechanism is found to be approximately proportional to

In this paper, we extend the work of Barton and Alexander [J. App. Phys. 66, 2800 (1989)] on the fifth-order corrected field expressions for a Hermite-Gaussian (0,0) mode laser beam to more general cases with adjustable parameters. The parametric dependence of the electron dynamics is investigated by numerical methods. Finally, the fifth-order corrected field equations for the Hermite-Gaussian (0,1) mode are also presented.

By means of 3D test particle simulation programs, the effect caused by the high-order corrections of Gaussian laser fields on the electron dynamics in a stationary ultraintense laser beam is examined. In this letter, special attention is given to the studying of the capture phenomenon (J. X. Wang et al., Phys. Rev.E58, 6575 (1998)), which shows interesting prospect making it to become a viable mechanism for laser-driven GeV electron accelerators without media involved. It was found that as w0≥50, where w0 is the beam width at the focus center, the paraxial approximation field (PAF) is good enough for reproducing all the electron dynamic characteristics, not only in qualitative detail, but also in quantitative detail.

By considering the influence of high-order field corrections upon the electronintense laser interactions in vacuum, we have demonstrated that great care should be taken of the electromagnetic fields when dealing with the nonlinear relativistic Lorentz equation for the electron motion. Moreover, the precision of different field descriptions corresponding to first-order corrections and paraxial approximation is investigated with examples of electron trajectories. It has been found that the paraxial field equations are accurate enough to describe the electron motion when the width of the laser beam described by symmetric fields meets kw0 60. In the case of asymmetric fields, the paraxial approximation is not appropriate to be used. This research is of great interest for the choice of electromagnetic fields in the study of laser acceleration of electrons.