Study of frequency of a coaxial-cavity gyrotron oscillator

Abstract

The eigenvalues of a coaxial cavity must be modified by the structural eccentricity (for instance. by the misalignment of the TImer rod), which causes an eigenfrequency shift. In this paper the eigenfrequency shift of the lrigher-order modes is numerically investigated in terms of the eigenvalue equation. Taking the TE,I,I"I, TE,l, 17 , 1 ,TE'l, 17,1 and TE,4, 17, I modes as examples, calculations show that the eigenfrequency of a mode may have a down-shift or up-shift.. which depends on the ratio of the outer conductor radius to the inner rod radius Raul ! R In' For a higher-order mode, the greater the value of Rou'! R ,. , the smaller the influence of the structural eccentricity on the eigenfrequency shift. Moreover, the structural eccentricity may have a weaker influence if the azimuthal index of tlle mode is higher.