Long-pulse millimeter-wave free-electron laser and cyclotron autoresonance maser experiments

Abstract

Experimental results on high-power long-pulse free-electron laser (FEL) and cyclotron autoresonance maser (CARM) experiments are summarized. Single-mode operation of a free-electron laser oscillator at 27.4 GHz with a Bragg resonator has been obtained, with an output power of 990 kW for a beam energy of 320 keV and transmitted current of 30 A, corresponding to an efficiency of 10.3%. Free-electron maser (FEM) amplifier operation at 35 GHz has yielded a gain of 26 dB with an output power of 800 kW, corresponding to an efficiency of 8.6%. CARM oscillator experiments at 32 GHz with a different electron gun have yielded lower powers because of poor beam quality; planned CARM experiments are discussed.