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

Abstract

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.Index Terms-Large-orbit gyrotron (LOG), terahetrzfrequency-range electromagnetic radiation.

High-harmonic gyrotrons with irregular microwave systems

“….This scheme was realized in the pulsed large-orbit 80 kV gyrotron [3]. Selective excitation at the third harmonic was achieved at a magnetic field close to 10.2 T. The output rf signal with a power of 100-250 W at a frequency of 0.74 THz corresponded to the transverse mode TE3,5.…”

Forward-wave enhanced radiation in the terahertz electron cyclotron maser

“…Thus, in some applications that do not require a high output power, the beam current is small and not qualified for the wave excitation threshold in a shortened cavity. Moreover, using various types of cavities, such as sectioned cavities, [19][20][21][22] cavities with axial irregularities, [23,24] or tapered cavities, [25,26] is demonstrated to be able to reduce the Q d value effectively.…”