Compression and acceleration of high-energy electron beam by intense short pulse laser

A generation of a high-density electron bunch is investigated. In order to compress a pre-accelerated electron bunch, we employ a laser of a TEM$_{10}$ mode + TEM$_{01}$ mode. This laser has a circle-shaped intensity distribution in transverse, and the pre-accelerated electrons are confined by the transverse ponderomotive force in transverse. A laser longitudinal electric field accelerates the pre-accelerated electrons further in longitudinal$^{[1]}$. At the parameter values of $a_{0}$=10, \textit{$\lambda $}=0.8 \textit{$\mu $m}, $w_{0}$=20\textit{$\lambda $}, $L_{z}$=10\textit{$\lambda $}, and \textit{$\gamma $}$_{i}$=7, the maximum electron energy is about 400 MeV. Here $a_{0}$ is the dimensionless value of the laser amplitude, \textit{$\lambda $} is the laser wavelength, $w_{0}$ is the laser spot size, $L_{z}$ is the pulse length and \textit{$\gamma $}$_{i}$ is the relativistic factor of the pre-accelerated electrons. The electrons accelerated are compressed into a length of about 10\textit{$\lambda $} from the original size of 150\textit{$\lambda $}. Our analytical study also shows that if the laser intensity and pre-accelerated electrons are in relativistic, the electron energy is proportional to $a_{0}$. This scaling law agrees well with the simulation results. [1] S. Miyazaki, S. Kawata, Q. Kong, et al., J. Phys. D: Appl. Phys. 38, pp. 1665-1673 (2005).