Low-voltage (750 V) free-electron laser operation at VHF (280 MHz)

A free-electron laser (FEL) type device that operates with a low-energy electron beam (/spl sim/0.7 keV) and a radiowave in the VHF range (/spl lambda/=1.1 m) is presented. The experimental device consists of a transmission-line (TEM-mode) cavity, and a folded-foil planar wiggler (/spl lambda//sub w/=4 cm). Coherent oscillations are observed in the fundamental cavity mode (0.28 GHz) and in higher order modes. This FEL-type device marks a record for an extremely low voltage operation.