The Nonlinear Analysis on a 210/240/270-GHz Megawatt-Class Gyrotron for DEMOs

Abstract

In this paper, a multifrequency, multimode, megawatt-class gyrotron has been analyzed, which can operate at frequencies of 210, 240, and 270 GHz with corresponding modes TE−35.15, TE−40.17, and TE−45.19, respectively. With the help of a time-dependent, multimode, self-consistent code, the startup scenarios have been investigated with considering ideal and realistic electron beam, respectively. In the analysis, the frequency-dependent effective conductivity was considered for the calculations of ohmic losses and beam-wave interaction. Meanwhile, to satisfy the multifrequency, multimode operation, a triode magnetron injection gun was employed, in which the electron parameters varying with the modulation voltage have been investigated. In the startups, the pitch factor and beam current varying with the beam voltage and modulation voltage have been discussed and investigated in theory and simulation. The results show that gyrotron can steadily operate at every operating mode under considerations of ideal and realistic beams.