The Israeli FEL project is based on a 2-6 MeV EN-Tandem van de Graff accelerator which was used before as an ion accelerator for nuclear physics experiments. The Weizmann Institute (Dannie Heinemann Accelerator Lab) gave permission to the FEL consortium to convert the machine into a high current electron accelerator and demonstrate its use in an FEL experiment.

This is an improved scheme relative to the only previous EA-FEL which was demonstrated at the Univ. of Cal. Santa-Barbara. Contrary to the previous experiment, this scheme uses straight geometry optics. The resonator is internal ,and the electron and collector power supplies are staged out of the accelerator. Because of these features this configuration is the only scheme that can be conceiveably developed for future high average power applications and posible CW operation.

The source of the electron beam is a 50kV 2 Amp electron gun seen at the front end of the accelerator. The high current electron beam is partially scraped and then injected into the accelerator by means of solenoid focusing lenses. The 5MegaV olt energy of the EN-Tandem accelerator corresponds to possible FEL lasing wavelengths in the entire milimeter and Far-Infrared range (100 µm to 10 mm with conventional wigglers and down to 10 µm with microwigglers). The present goal of the projec t is to demonstrate the feasibility and applications of a mm wavelength FEM operating at the KWatt average power level.

Beyond the technical demonstration of high power lasing and application of the Tandem EA-FEL the FEL team has a scientific interest mostly in the study of the limits of coherence (monochromaticity) of the FEL light and the dynamics of coherence establishment. The high coherence properties of FEL is not only of practical importan ce but also gives rise to scientific research problems of quite fundamental nature in laser physics. The expected long electron beam pulse duration of the Israeli FEL experiment will provide a unique set-up for studing and improving the EA-FEL coherence properties.