Simulating the effects of timing and energy stability in a laser wakefield accelerator with external injection

One of the most compelling reasons to use external injection of electrons into a laser wakefield accelerator is to improve the stability and reproducibility of the accelerated electrons. We have built a simulation tool based on particle tracking to investigate the expected output parameters. Specifically, we are simulating the variations in energy and bunch charge under the influence of variations in laser power and timing jitter. In these simulations a a₀ = 0.32 to a₀ = 1.02 laser pulse with 10% shot-to-shot energy fluctuation is focused into a plasma waveguide with a density of 1.0×10²⁴ m^-3 and a calculated matched spot size of 50.2 μm. The timing of the injected electron bunch with respect to the laser pulse is varied from up to 1 ps from the standard timing (1 ps ahead or behind the laser pulse, depending on the regime). The simulation method and first results will be presented. Shortcomings and possible extensions to the model will be discussed.