No abstract

In this paper we compared the efficiency of the cylindrical, conical, and biconical types of gyrotron resonators. Based on the results of comparing the three studied variants of gyrotron profile, it was concluded that the regular-type profile is the least efficient. This type of a resonator made it possible to achieve the level of efficiency of only 23 %, which can be increased in the regular-waveguide gyrothrons only through several modes or by recovering the electrons on the collector. The medium efficiency option is the biconical profile of the resonator. Its efficiency accounted for 42 %. Through a scientific study we revealed an increase in the efficiency for gyrotrons with conical resonators from 23 to 50 % in the TE01 wave. It is worth mentioning that obtaining such efficiency requires phase grouping of the electrons in an increasing high-frequency field by means of an electromagnetic field with further selection of energy from the electron beam in a strong decaying electromagnetic field. The efficiency of 50 % exceeds significantly that of a gyrotron with a regular cavity profile of ~30 %. The gyrotron efficiency for a waveguide profile with a conical resonator and with recovery on the collector can reach 80 %. To carry out the calculations, the KEDR software package was used, and the optimization of the gyrotron parameters, in particular, was carried out using the GYRO-K software. This software has several advantages over other similar options based on the “PIC” code. GYRO-K makes it possible to obtain a high convergence rate when solving boundary value problems, as well as to solve the problem of optimizing the waveguide profile of gyroresonance devices with an acceptable computational burden. Conical cavity gyrotrons can be widely used in industry to create effective gyrotrons for spectroscopy, diagnostics of various media, and for technological needs.

В статье описан новый тип электронного прибора-гиротон на гофрированном резонаторе. В данном приборе не происходит пространственная группировка электронного потока, однако имеется возможность достижения высокого коэффициента преобразования мощности электронного потока в мощность электромагнитной вращающейся волны. Прямолинейный на входе в прибор электронный поток за счет начального отклонения его от оси замедленной TM11-волны отдает свою продольную энергию этой же волне с КПД более 80 %. Описанный в статье метод сводит 3D-задачу к 1D-задаче, что повышает скорость и точность решения краевой задачи. Разработанная математическая модель является основой для компьютерной программы расчета и оптимизации процессов взаимодействия релятивистских электронных потоков с полями нерегулярных круглых волноводов Gyro-K, которая входит в программный комплекс КЕДР. Разработанная математическая модель процессов взаимодействия релятивистского электронного потока с полями нерегулярных круглых волноводов и резонаторов позволяет провести теоретический анализ работы гиротона-генератора с гофрированным резонатором. Как результат, в статье продемонстрирована возможность обеспечения электронного КПД более 80 % и выходной мощности до 30 МВт для разработанной математической модели гиротона на гофрированном резонаторе. Ил. 9. Библиогр.: 22 назв.

The results of calculations of a nonlinear model of a tunable frequency gyrotron on a cone-shaped waveguide and the main wave TE01 are presented. It is shown that the adjustment range can reach 2.8 %. To extend this band, it is necessary to lengthen the cone-shaped part of the waveguide without changing the angle of increase in the radius of the waveguide.The wave efficiency of a waveguide expanding along the axis is 21 % at a working frequency of 10 GHz. To achieve these parameters, it is necessary to divide the gyrotron electromagnet into two parts – the main electromagnet and auxiliary one, which has a limited length and can move along the waveguide. The second magnet can be made in the form of a set of individual electromagnets of limited length the set of electromagnets must fill the entire length of the cone-shaped waveguide. The fulfillment of this condition will allow to move the resonant magnetostatic field along the waveguide by switching the current in the coils of this set of electromagnets, which will exclude the mechanical movement of the auxiliary electromagnet. At a frequency of 200 GHz, the wave efficiency is reduced to 15 %, while the ohmic losses in the walls of the waveguide are 3 % of the power of the electron beam.The dependence of the gyrotron efficiency on the initial angular spread of electron velocities was investigated. It was concluded that the initial angular spread of the electron velocities has very little effect on the efficiency of the tunable gyrotron.The wave efficiency of a waveguide narrowing in length can reach 29 % at a frequency of 200 GHz, ohmic losses in the walls of a copper waveguide amount to 4 % of the power of the electron beam. Calculations have shown that a lamp backward wave gyrotron with a waveguide narrowing along the axis is more efficient than the version of the gyrotron traveling wave tube. However, in both cases, the synchronous value of the magnetostatic field must be displaced along the axis, depending on the required operating frequency, otherwise there occurs either a rearrangement of the electron beam or a return of the energy to the high-frequency field by the electron beam.