Design of an electron gun with FEA cathode for THz devices

The detection and generation of THz signals (300 GHz-3 THz) is technologically challenging due to the lack of sufficient power sources. A possible approach to increase the output power is by the use of vacuum THz amplifier, such as a travelling wave tube (TWT) or a klystron. A critical part of those devices is represented by the electron gun that has to deliver a sufficient current in order to allow an amplification of the THz signal. Cold cathodes based guns represent a possible solution because they can reach high current density, several tens of amps per centimetre square and have many advantages, respect to thermionic cathode, like the room-temperature operation, the possibility of patterning to create the desired beam shape and the reduced dimensions. In this paper, the authors described the design of an FEA electron gun that can suitable as an electron source in the vacuum THz device where thermal cathode is used. The characteristics of the electron gun were studied with MAGIC 3D PIC simulator.