Terahertz Orotrons and Oromultipliers

The capabilities of two types of terahertz sources based on stimulated Smith-Purcell radiation of electrons in open cavities are discussed. A series of developed pulsed orotrons provides coherent radiation with an output power of 1-0.1 W in the frequency range of 90-410 GHz, with high frequency stability and broad-band electromechanical frequency tuning. A promising alternative source with smaller currents than that in orotrons is a frequency multiplier based on excitation of a surface wave of a periodic structure and Smith-Purcell radiation of arising electron bunches inside the orotron cavity. In contrast to a number of works where only an open grating is used, exploiting a cavity enables a stimulated radiation process with a much higher power. The developed theory demonstrates the possibility of single-mode generation in such multipliers with wide electron beams.