Terahertz Free Electron Laser with an Electrodynamic System Based on the Excitation of Talbot-type Supermode

In this work we describe the concept of an electron maser based on the excitation of the single supermode formed by a fixed set of transverse eigenmodes is proposed. The high-Q supermode is proposed as an operating mode. This mode is formed inside a simple cavity by a set of its eigenmodes. The supermode is high-Q due to the Talbot effect, namely, periodic reproduction of the transverse structure of a multimode wave field in an oversized waveguide. Two mirrors at the input and output of the waveguide provide the mode localization inside the cavity.