J. Rossbach et al., FUNDAMENTAL LIMITATIONS OF AN X-RAY FEL OPERATION DUE TO QUANTUM FLUCTUATIONS OF UNDULATOR RADIATION, Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment, 393(1-3), 1997, pp. 152-156
In this paper we show that the effect of energy diffusion in the elect
ron beam due to quantum fluctuations of undulator radiation imposes fu
ndamental limit towards achieving very short wavelength in the FEL amp
lifier.