<title>The Dispersive FEL - A Hybrid Optical Klystron-Free Electron Laser</title>

Abstract

The dispersive free-electron laser (dispersive FEL) is a normal free-electron laser (FEL) with a dispersive magnetic field, similar to that of the optical klystron (OK), superimposed on some of the undulator magnets. Small signal gain, electron energy acceptance bandwidth and saturation efficiency of the normal FEL, OK and dispersive FEL are compared. It is found that for a given electron energy acceptance the dispersive FEL has about a factor of two higher gain than the OK. For a given length, and some non-negligible intrinsic cavity loss, the dispersive FEL has higher saturated output power than the normal FEL. For storage ring operation, where the intrinsic energy bandwidth is small and the length is limited, the dispersive FEL has higher gain than either the conventional FEL or the optical klystron.