The prospects of an X-ray free electron laser using stimulated resonance transition radiation

This paper considers stimulated X-ray emission from a relativistic beam of electrons passing through a periodic, heterogeneous medium and interacting with a plane wave. Amplification of the wave occurs when there is bunching of the electrons due to this interaction. The gains for warm and cold electron beams are derived neglecting space charge and multiple scattering. High-current, ultrarelativistic electron beams appear to be the most likely to produce reasonable gain. An estimate of the multiple scattering for the examples cited show the net gain to be severely affected.