STATUS OF THE FRITZ HABER INSTITUTE THZ FEL

The IR and THz FEL at the Fritz Haber Institute (FHI) in Berlin [1] is designed to deliver radiation from 4 to 500 microns. A single-plane-focusing undulator combined with a 5.4 m long cavity is used in the mid-IR (< 50 micron), while a two-plane-focusing undulator in combination with a 7.2 m long cavity with a 1-D waveguide for the optical mode, will be used for the far-IR. A key aspect of the accelerator performance is low longitudinal emittance, < 50 keV-psec, at 200 pC bunch charge and 50 MeV, from a gridded thermionic electron source. We utilize twin accelerating structures separated by a chicane to deliver the required performance over the 15- 50 MeV energy range. "First Light " is targeted for the centennial of the FHI in October 2011. Installation and commissioning progress to date is described