A TABLE-TOP X-RAY FEL BASED ON THE LASER WAKEFIELD ACCELERATOR-UNDULATOR SYSTEM

Laser wakefield acceleration makes it possible to build a compact elec tron linac. While acceleration is attributed to longitudinal wakefield s, transverse wakefields simultaneously generated by a short laser pul se can serve as a plasma undulator with a very short wavelength equal to half of the plasma wavelength. We propose a new FEL concept for X-r ays based on a laser pulses delivered from a table-top terawatt laser. The system is composed of the accelerator and undulator stages in a t able-top size. A low energy electron beam is accelerated due to laser wakefields in the accelerator stage. A bunched electron beam travellin g to the opposite direction of driving laser pulses produces a coheren t X-ray radiation in the undulator stage. A practical configuration an d its analysis are presented.