Generation of a microelectron beam by an intense short pulse laser in the TEM(1, 0) + TEM(0, 1) mode in vacuum

Abstract

The generation of a high energy microelectron bunch in vacuum by an intense short pulse laser in the TEM(1, 0) + TEM(0, 1) mode is investigated in this paper numerically and analytically. A focused short pulse laser in the TEM(1, 0) + TEM(0, 1) mode has a confinement effect on electrons in the transverse direction due to the transverse ponderomotive force, and at the same time the electrons are accelerated and compressed longitudinally by a longitudinal electric field. In our three-dimensional particle simulations, the maximum kinetic energy of electrons reaches 455 MeV, the maximum density is 3.87 × 1010 cm−3, and the normalized transverse and longitudinal rms emittances of accelerated electrons are of the order of 10−6 m rad at the following parameter values: a0 = eE0/(meω c) = 10 (where a0 is the dimensionless parameter of the laser amplitude, e and me are the electron charge and rest mass, respectively, E0 is the laser amplitude, ω the angular frequency of the laser and c the speed of light in vacuum), a laser wavelength λ = 0.8 µm, laser spot size 20λ, laser pulse length 5λ and initial electron velocity 0.99c. Moreover, the transverse and longitudinal sizes of the compressed electron bunch are about 600λ and 10λ, respectively. In this paper, we also present a scaling law of the maximum electron energy. The estimated results of the maximum electron energy coincide well with the simulation results.