Abstract
The dynamics of electron injection from a shock front under a laser condition of a0 > 3 and tight focusing (FWHM < 10 μm) laser condition has been studied by numerical simulations. Compared to a regular longitudinal shockfront injection, the transverse injection starts near the edge of the bubble with a narrow energy spread of < 13 MeV. The trajectories of the transverse injected electrons are more coherent than the longitudinal injection. By applying the tilted shock front, the betatron oscillation amplitude is significantly larger than the un-tilted shock front. The enhancement of the betatron radiation brightness has been observed.