Free-electron laser experiments with and without a guide magnetic field - A review of millimeter-wave free-electron laser research at the Naval Research Laboratory

It is pointed out that the free-electron laser (FEL), when driven by an intense electron beam of moderate energy, is capable of generating extremely high-power, continuously tunable millimeter wavelength radiation with high gain and moderate efficiency. Such a device may have important applications, either as an oscillator or an amplifier, for such objectives as plasma heating, advanced electron accelerators, communications, or for other high-power applications for which no comparable sources exist. The Naval Research Laboratory (NRL) has played a pioneering role in the experimental development of FEL's, and in the development of the theory for such devices. Attention is given to pulseline accelerator experiments, and linear induction accelerator experiments.