The third cyclotron harmonic gyromonotron with a ridged waveguide

Eigenvalues and fields of TE10 and TE30 modes in a ridged waveguide are derived in this paper. The field distribution of TE10 indicates the difficulty of peniotron's realization in the waveguide. After comparing the fields of TE10 and TE30 with that of TE10 and TE30 rectangular waveguide modes, nonlinear calculations have been carried out on models of large-orbit gyrotron oscillators with a ridged resonator or a rectangular one. It has been studied that the transverse fields affect the efficiency of the gyrotron at the fundamental or the third cyclotron harmonic. The computational results show the gyrotron oscillator at the third cyclotron harmonic and using TE301 in the ridged waveguide has 51% high efficiency.