The interaction of free electrons with intense laser beams in vacuum is studied using a three-dimensional 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 article. The accelerated GeV electron bunch is a macropulse, with duration equal to or less than that of the laser pulse, which is composed of many micropulses that are periodic at the laser frequency. The energy spectrum of the CAS electron bunch is presented. The dependence of the energy exchange in the CAS on various parameters, e.g., a0 (laser intensity), w0 (laser radius at focus), τ (laser pulse duration), b0 (the impact parameter), and θi (the injection angle with respect to the laser propagation direction), are explored in detail. A comparison with diverse theoretical models is also presented, including a classical model based on phase velocities and a quantum model based on nonlinear Compton scattering.

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.

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 considering the influence of high-order field corrections upon the electron-intense 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.

In this paper, the free-electron scattering by continuous or pulsed laser beams has been investigated in details. It is found that when Q = eE/(mwc) greater than or similar to 100 an electron can be captured aid violently accelerated to GeV energy under proper conditions. From the quantum viewpoint, we can explain this effect on the basis of non-linear and stimulated Compton scatterings. This phenomenon provided us with a new far-field laser acceleration mechanism,whose practical feasibility and application possibility are also discussed.

We show that there are two mechanisms responsible for the net energy exchange between an intense pulsed laser and an electron in vacuum, namely, stimulated Compton scattering and nonlinear Compton scattering(NLCS). For NLCS, being the only effect in a mono-frequency continuous laser beam, its contribution is also independently determined. The characteristics of these two mechanisms in connection with the net energy exchange are studied. For the case of a pulsed laser field, it is found that the maximum net energy exchange by NLCS is approximately proportional to Q02(Q0 ≡ eE0/(me ωc)) for Q0 ≳ 100. In addition, the relative importance of these two mechanisms to the net energy exchange at different intensities is explored.

With both analytical and numerical simulation methods, it is found that, by using an intense laser pulse with sharply rising or falling edges in vacuum, an electron can be accelerated to very high energies, which approaches the upper-limit of the energy predicted by the half-wavelength acceleration mechanism. Because the form factor of the laser pulse is like the shape of a shock wave, we call this kind of acceleration mechanism as shock-pulse-laser acceleration.

We present in this paper a quantitative study of an effect, in which a low-energy free electron is captured and violently accelerated to GeV final kinetic energy by a stationary extra-high-intensity laser beam (Q0 identical witheE/m(e)omegac greater, similar100). The conditions under which this phenomenon can occur, such as the momentum range, incident angle of the incoming electron, the waist width of the laser beam, etc., have been investigated in detail.

In this paper we present the inelastic scattering of electrons by a pulsed laser beam in free-space using the computational simulation technique. Emphasis is put on the inelastic scattering resulting from the time-varying nature of the pulsed laser fields. It is also found that the effects can be explained within the framework of time-dependent ponderomotive potentials if the field intensity .

In this paper, an approximate pulsed-laser-beam solution of Maxwell's equation in vacuum is derived. Then with the numerical simulation method, electron acceleration induced by high-intensity [Q(0)=eE(0)/(m(e)omega c)=3] lasers is discussed in connection with the recent experiment of Malka et al. It is found that the maximum energy gain and the relationship between the final energy and the scattering angle can be well reproduced, but the polarization effect of electron-laser interactions is not very prominent. These results show that the ponderomotive potential model is still applicable, which means that the stimulated Compton scattering is the main fundamental mechanism responsible for the electron acceleration at this laser intensity.

We present a novel phenomenon of electron dynamics in an ultra-intense pulsed laser beam. When the field intensity is sufficiently strong (Q ≡ eE0meωc ≳ 100, Q is a dimensionless parameter measuring the field intensity), the electron can be captured by the laser beam and thus violently accelerated by the laser field.

By calculation of the classical Newton-Lorentz equation and neglecting the radiation reaction, we find that when an electron is scattered by an intense continuous monochromatic laser beam (Q = eE/(m(e)wc) > 0.1 in the interaction region), there can be not only momentum transfer but also noticeable energy transfer between the free electrons and the laser beam. This kind of inelastic effect comes from nonlinear Compton scattering.

This paper reports on an interesting phenomenon in strong-field laser physics. It has been found, by numerical simulation method, that when interacting with an extraintense stationary laser beam (Q greater than or similar to 100, when Q is the dimensionless measure of the field intensity [Y. K. Ho, Phys. Lett. A 220, 189 (1996)], the electron can be captured and violently accelerated by the laser beam field. [S1063-651X(98)00811-3].

Electron acceleration in an axisymmetric radially-polarized laser field has been studied by both analytical and numerical calculations. The relationships concerning acceleration and field parameters are investigated together with the discussion on the transimitting characteristics and quality of electron beam.

We show that there can be noticeable energy exchange between the scattering electrons and the stationary laser beam when the field is strong enough (Q ≡ eEmeωc > 0.1 in the interaction region). The numerical scaling relationship between the interaction parameters and the inelastic effect, which comes from nonlinear Compton scattering, is given.

We report for the first time on the study of electron scattering in three-dimensional continuous laser beams by a computer simulation technique with emphasis on investigating the transition from conventionally elastic to inelastic scattering. The crucial factors for an inelastic scattering are found to be the strength of laser fields (Q = eAmec2 > 0.1) and small incident angles (θ ⪡ π4).