Efficient confinement and acceleration of relativistic electron bunch in interaction with higher modes of Hermite–Gaussian laser beam

In this paper, the generation of high efficiency electron bunch in vacuum by utilizing Hermite–Gaussian laser beam in the HG1,1 mode and a superposition of HG1,0 and HG0,1 modes are studied. The mechanism of electron-wave energy exchange is explained in detail, and it is obtained that the interaction takes place in three fundamental steps. It is demonstrated that the particle jumping to enter the wave acceleration channel by means of the intense laser ponderomotive force and the synchronization of the electron velocity with the wave phase velocity to transfer energy to the particle are two principal steps. Then, the dynamics of an electron bunch and its confinement mechanism is investigated. It is found that the transverse ponderomotive force (Fpr) of the laser beam with the HG1,0+HG0,1 mode, by creating a potential well, confines the electrons in the radial direction and, therefore, produces a higher quality electron beam. In our simulation, the length and radius of output electron bunch are about 20λ and 450λ, respectively, its mean energy is 266 MeV, and the maximum kinetic energy of electrons reaches 700 MeV.