Submillimeter FEL facility at the ENEA-Frascati Research Center

Low energy rf electron-beam sources have potential use as a driver for FELs operating in the far IR, since they can provide short pulses of coherent radiation in a spectral region not covered by conventional lasers. The ENEA PEL facility utilizes a 5-MeV microtron capable of delivering 20-ps bunches with a 4-A peak current as the electron beam source. The layout of the facility is sketched in Fig. 1. A resonator chamber, which allows straight-line electron-beam propagation, was designed and built to be used as a test-bed for different short length guiding structures as dielectric loaded waveguides (Cerenkov-FEL),1 metal gratings (Orotron),2 short period undulators. The first use of this facility has been the test of a Cerenkov-FEL device. A quasioptical resonator with a novel electron-beam injection scheme and an electron transparent output coupler was utilized for this experiment.