Tapering enhanced stimulated superradiant amplification

Abstract

High conversion efficiency between electrical and optical power is highly desirable both for high peak and high average power radiation sources. In this paper we discuss a new mechanism based on stimulated superradiant emission in a strongly tapered undulator whereby a prebunched electron beam and focused laser are injected into an undulator with an optimal tapering calculated by dynamically matching the resonant energy variation to the ponderomotive decelerating gradient. The method has the potential to allow the extraction of a large fraction (∼50%) of power from a relativistic electron beam by converting it into coherent narrow-band tunable radiation, and shows a clear path to very high power radiation sources of EUV and hard x-rays for applications such as lithography and single molecule x-ray diffraction. Finally, we discuss a technique using chicane delays to suppress the sideband instability, improving radiation generation efficiencies for interaction lengths many synchrotron wavelengths long.

Keywords

• laser particle acceleration
• free electron laser
• sideband suppression
• extreme ultraviolet lithography
• x-ray diffraction