Demonstration of a Two-Stage Backward-Wave-Oscillator Free-Electron Laser

Abstract

An experimental study of a two-stage millimeter-wave source in which the same intense relativistic electron beam first produces powerful (500-MW) radiation at 12.5 GHz and then uses that radiation as a "pump" for a free-electron-laser interaction at frequency $f>140$ GHz is described. Implication for two-stage free-electron-laser experiments with reduced electron energy requirements are discussed.