Generating High-Brightness Electron Beams via Ionization Injection by Transverse Colliding Lasers in a Plasma-Wakefield Accelerator

Laser Fusion Research Center, China Academy of Engineering Physics, Mianyang, Sichuan 621900, China(Received 14 January 2013; published 2 July 2013)The production of ultrabright electron bunches using ionization injection triggered by two transverselycolliding laser pulses inside a beam-driven plasma wake is examined via three-dimensional particle-in-cell simulations. The relatively low intensity lasers are polarized along the wake axis and overlapwith the wake for a very short time. The result is that the residual momentum of the ionized electronsin the transverse plane of the wake is reduced, and the injection is localized along the propagation axisof the wake. This minimizes both the initial thermal emittance and the emittance growth due to trans-verse phase mixing. Simulations show that ultrashort ( 8fs) high-current (0.4 kA) electron buncheswith a normalized emittance of 8.5 and 6 nm in the two planes, respectively, and a brightness of1:7 10