Design and development of the TAU Tandem FEL

This paper presents a status report on Tandem electrostatic FEL which has been developed based on the 5 MeV linear accelerator at the Weizman Institute. The FEL is designed to operate near 100 GHz and is comprised of the following basic components: (1) an injector based upon a Pierce e-gun which provides a 1.8 amp beam at 50 keV. (2) an electrostatic accelerator that accelerates the beam to 1.4 MeV at the high voltage terminal (in the middle of the accelerator tank) where the wiggler mm-wave cavity is placed. (3) a depressed collector at ground potential. The electron beam is transported towards the wiggler with the aid of magnetic focusing coils, which inject the beam into the electrostatic accelerator tube and then is focused into the wiggler by means of 4 quadruple lenses. The beam transport is corrected by use of steering magnets at the entrance and at the exit of the wiggler, and is monitored with the aid of 3 fluorescent screens (S1-S3) and CCD cameras.