Experimental Realization of the High-Harmonic Gyrotron Oscillator With a Klystron-Like Sectioned Cavity

High-harmonic terahertz-frequency-range gyrotrons require long-length operating cavities due to both weak electron-wave coupling and relatively low electron currents. Since diffraction Q-factors of such cavities are very high, a great share of the radiated RF power is spent to ohmic losses. A sectioned klystron-like cavity was proposed as a way to combine a long electron-wave interaction region with a relatively low diffraction Q-factor. In this brief, results of the first experiment under the high-harmonic gyrotron with the klystron-like cavity are reported. In this experiment, selective operation of the gyrotron at the second (0.55 THz) and the third (0.74 THz) cyclotron harmonics has been observed.