Cascaded Laser Wakefield Acceleration Scheme for Monoenergetic High-Energy Electron Beam Generation

Abstract

Cascaded laser wakefield acceleration (LWFA) of electrons is promising for producing monoenergetic electron beams well beyond 1 GeV by separating and controlling electron injection and postacceleration in two LWFA stages. We have demonstrated that electrons with Maxwellian spectra generated from the first LWFA assisted by tunnel-ionization-induced injection were seeded into the second LWFA and then accelerated to be a 0.8 GeV quasi-monoenergetic electron beam. Further acceleration toward multi-GeV may be fulfilled with a long plasma channel. Optical guiding of intense femtosecond laser pulses for powers up to 160 TW over a 4-cm long ablative capillary discharge plasma channel and laser wakefield acceleration of electrons well beyond 1 GeV were experimentally demonstrated. By employing an oxygen-containing ablative capillary, electron beams with energies extending up to 1.8 GeV were generated by using 130 TW, 55 fs laser pulses.