Matching-based two-color X-ray free-electron laser generation utilizing laser–plasma accelerated electron beam

Abstract

Laser-plasma accelerator (LPA) has great potential to realize a compact x-ray free-electron laser (FEL), which is limited by the beam properties currently. Two-color high intensity x-ray FEL provides a powerful tool for probing ultrafast dynamic systems. In this paper we present a simple and feasible method to generate a two-color x-ray FEL pulse based on an LPA beam. In this scheme, time-dependent mismatch along the bunch is generated and manipulated by the designed lattice system, enabling FEL lasing at different wavelength within two undulator sections. The time separation between the two pulses can be precisely adjusted by varying the time-delay chicane. Numerical simulations present two-color soft x-ray FELs with gigawatt level peak power and femtosecond duration can be generated, which confirm the validity and feasibility of the scheme.