Design of a tandem accelerator free electron laser

The motivation for using a tandem electrostatic accelerator as an electron accelerator for a free electron laser (FEL) is presented. The adaptation of the HVEC EN tandem at the Weizmann Institute for this purpose, electron beam optics and nonlinear FEL computation relevant for this FEL realization are described. In the tandem configuration the terminal is held at a positive potential. The electron beam is accelerated from ground potential to the terminal in one beam tube and then decelerated down the other beam tube. The FEL wiggler and cavity are at the terminal. Due to the beam energy recovery this scheme produces a high power beam at the terminal with a small investment in electrical power. (orig.)