Selecting the time dependence of the accelerating voltage fluctuations for modeling of the spectral characteristics of a megawatt-level gyrotron

Abstract

The spectral characteristics of the gyrotron with a megawatt power level in the 170 GHz range were modeled numerically. The calculations were carried out using the large particle method implemented in the KARAT code. The problem of three-dimensional modeling of the excitation of an asymmetric type mode was reduced to a 2.5-dimensional one. For this model, the presence of high-frequency fluctuations at the output of high-voltage power supplies, which determine the initial energy of electrons, was taken into account. The relationship between the shape and width of the radiation spectrum of the simulated gyrotron and the time dependence of the accelerating voltage has been studied. It is shown that the best agreement with experimental data is obtained by combining a relatively slow sawtooth change in particle energy with fast random fluctuations.