Abstract
High frequency, frequency tunable, medium power gyrotrons (Gyrotron FU series) are being developed in Fukui University as millimeter to submillimeter wave sources. The gyrotron series has achieved frequency tunability in a wide range from 38 to 889 GHz and medium output power from 0.1 kW to several kW. For the application to many fields, stabilizations of both amplitude and frequency of their outputs have been achieved. In this paper, the advances in recent few years are summarized.
