Poole, M.W.
(Mike Poole)

WEBOS05 The Harmonically Coupled 2-Beam FEL
Brian W.J. McNeil, Gordon Robb (Strathclyde University, Glasgow), Mike Poole (CCLRC/DL/ASTeC, Daresbury, Warrington, Cheshire)

A 1-D model of a 2-beam Free Electron Laser amplifier is presented. The two co-propagating electron beams have different energies, chosen so that the fundamental resonant FEL interaction of the higher energy beam is at an harmonic of the lower energy beam. In this way, a coupling between the FEL interactions of the two beams occurs via the harmonic components of the electron bunching and radiation emission of the lower energy interaction. Such resonantly coupled FEL interactions may offer potential benefits over existing single beam FEL schemes. A simple example is presented where the lower energy FEL interaction only is seeded with radiation at its fundamental resonant wavelength. It is predicted that the coherence properties of this seed field are transfered via the resonantly coupled FEL interaction to the un-seeded higher energy FEL interaction, thereby improving its coherence properties over that of a SASE interaction alone. This method may offer an alternative seeding scheme for FELs operating in the XUV and x-ray regions of the spectrum.