Sharp electron density for laser wakefield accelerator

The electron densities of plasma channels are studied for the electron injection in laser wakefield acceleration and the effect of the finite transition scale length is studied using one-dimensional particle in cell code. The simulation indicates that the density transition scale length must be less than 2 µm for the electron injection. The density transition scale lengths were measured by an interferometer at different times. The feasible electron density structure was formed 1.2 ns after laser pulse.