An XUV-FEL amplifier seeded using high harmonic generation

A detailed design of a free electron laser (FEL) amplifier operating in the extreme ultra violet (XUV) and seeded directly by a high harmonic source is presented. The design is part of the 4th generation light source (4GLS) facility proposed for the Daresbury Laboratory in the UK which will offer users a suite of high brightness synchronised sources from THz frequencies into the XUV. The XUV-FEL will generate photons with tunable energies from 8 to 100 eV at giga-watt peak power levels in near Fourier-transform limited pulses of variable polarisation. The designs of the high harmonic generation (HHG) seeding, FEL amplifier and synchronising systems are presented. Numerical simulations quantify the FEL output characteristics. 5 Author to whom any correspondence should be addressed. New Journal of Physics 9 (2007) 82 PII: S1367-2630(07)40943-