Complicated cavities for high-harmonic THz electron masers

To ensure high selectivity of excitation of the operating high-cyclotron-harmonic modes in gyrotrons, it was proposed to use resonators of complex shape with one or more longitudinal or transverse selective grooves. The use of cavities of this type can be the way to achieve stable single-mode gyrotron operation at frequencies of about 1 THz with a sufficiently high (several kW) output radiation power level.