X-Ray Free Electron Lasers

HHG laser seed--an alternative to harmoniccascadesExample with seed at 30 nm, radiating in the water windowFirst stage amplifies low-power seed with “optical klystron”More initial bunching than could be practically achieved with a single modulatorOutput at 3.8 nm (8 th harmonic)100 kWl =30 nm1 GeV beam500 A1.2 micron emittance75 keV energy spreadModulator30 nm, L=1.8 m300 MW output at 3.8nm (8 th harmonic) froma25 fs FWHM seedModulator30 nm, L=1.8 mRadiator3.8 nm, L=12 mCourtesyH. KapteynOr, X-ray laser seedGullans et al. (2007)