Pulse front tilt steering in laser plasma accelerators

Abstract

We report on the effect of laser spatiotemporal coupling in laser plasma accelerators. Pulse front tilt in the driving laser causes asymmetry in the wakefield, resulting in deflection of the electron beam from the laser axis. We explore the physical mechanisms and propose a quantitative model of electron steering, which is validated with particle-in-cell simulations. Even a small amount of pulse front tilt can result in beam steering in the final down ramp of the plasma profile, which may lead to unexpected beam-pointing errors or fluctuations. On the other hand, it can be used to govern the final beam direction, which has consequences for staging laser plasma accelerators in a high-energy physics collider as well as x-ray generation for biological imaging.