Electron self-injection threshold for the tandem-pulse laser wakefield accelerator

Abstract

A controllable injection scheme is key to producing high quality laser-driven electron beams and x rays. Self-injection is the most straightforward scheme leading to high current and peak energies but is susceptible to variations in laser parameters and target characteristics. In this work, improved control of electron self-injection in the nonlinear cavity regime using two laser-pulses propagating in tandem is investigated. In particular, the advantages of the tandem-pulse scheme in terms of injection threshold, electron energy, and beam properties in a regime relevant to betatron radiation are demonstrated. Moreover, it is shown that the laser power threshold for electron self-injection can be reduced by up to a factor of two compared to the standard, single-pulse wakefield scheme.