Gyrotron FU series — current status of development and applications

The gyrotrons developed at Fukui University (“Gyrotron FU series”) are high-frequency, medium-power devices, covering broad frequency bands in the millimeter and submillimeter wavelength regions. Currently, the “Gyrotron FU series” consists of eight gyrotrons. Distinguishing features of these devices are described: Frequency tunability from 38 to 889 GHz; frequency and amplitude modulation of generated radiation; complete cw operation for long periods, exceeding 15 h and high level of stabilization of the output power by feed-back control of the anode potential. The gyrotrons from FU series were successfully used in plasma scattering experiments, electron spin resonance spectroscopy and in-depth studies of mode competition and mode cooperation. In this paper, we summarize and illustrate the achievements of the “Gyrotron FU series” and present some of the ongoing projects for development of novel gyro-devices and quasi-optical transmission systems