Observation of the spontaneous and stimulated emission from the ISAS compact FEL in the millimeter wave region

A compact FEL for submillimeter and far-infrared regions is studied in the Institute of Space and Astronautical Science. The FEL can be made compact by using an electrostatic accelerator and a micro wiggler. The FEL has a tabletop size with a total length of 2.5 m. At the preliminary phase, we aim to oscillate the FEL in the short millimeter wave. o cathode is used as the source of an electron beam. Characteristics of the electron beam were improved by means of designing the electron gun and the photo cathode. This electron beam was injected into an FEL resonator consisting of a waveguide and distributed Bragg reflectors and a spontaneous emission was observed. When we increased the current of the electron beam that passed through the resonator, a stimulated emission was observed with a frequency of 96 GHz and a peak power of 3.4 mW.