Terahertz superradiation from cylindrical surface wave-annular electron beam interaction within a 3-mirror quasi-optical cavity

A cylindrical surface wave-annular electron beam interaction in a special 3-mirror quasi-optical cavity is presented and explored. The study demonstrates THz free electron superradiation from the interaction of cylindrical surface wave and annular electron beam that forms a resonance within the structure, with the 3-mirror quasi-optical cavity enhancing the intensity of superradiation by more than one order of magnitude. Moreover, this system can work with 2nd harmonic superradiation at 0.607 THz with only about 30 A/cm² which is a relatively low value.