.3 Mm, Band Second Harmonic Gradient Complex Cavity Gyrotron Note - Wave Interaction

The High Power Microwave (HPM) technology is a new and frontier science which rose in the 1970s.Because of continuing demands of higher power, higher energy and higher frequency microwave sources in military and scientific research, the young science has developed rapidly and is receiving widespread attention. Now it may be applied in many areas such as military and scientific experiment ,industrial processing, new material preparing, medical science, biology, and so on. Being high power resources of millimeter-wave radiation, gyrotron has been pay much respect in the world for vast application in many areas such as plasma heating, liner accelerators, millimeter wave radar communications, electronic countermeasure, microwave arms and so on. Specifically in thirty years later, there is much developments on gyrotron. At home, in the later of 1970's, Prof.Liu Shenggang began the research on electron cycotron maser, and later, the group leaded by Prof. Li Hongfu has done much research work on gyrotron also, and successfully developed a first Ka band third harmonic gyotron oscillator with a permanent magnet system. There is not only much development on the 8mm band gyrotron, but the research of the 3mm band gyrotron has started already in the world. Because there is advantage of its own for the 3mm band, it may be applied in many areas such as radar, microwave arms, plasma heating and so on. But the research report about the 3mm band second harmonic complex cavity with gradual transition isn't found at home. The paper analyses the multiple modes interaction with an electron beam for 94GHZ 3mm band second-harmonic gyrotron and simulated it by the self-consistent nonlinear theory. The main works of this paper are listed as following: 1. The general equations for the RF fields in a tapered waveguide open resonator with axial symmetry are deduced by the coupling wave theory and analysed under the suitable boundary conditions. And the other parts of the cavity of gradual transition are dealed with in common way. 2. The process of the beam-wave interaction is analysed by the self-consistent nonlinear theory and the electron magnetic equation and equation governing the motion are deduced, in which the beam-wave interaction is taken into account. 3. It is made the self-consistent nonlinear theoretical model, in which the beam-wave interaction is taken into account. Based on the theoretical model, the interaction between the electron beam and RF field for second-harmonic is simulated, by the code of self-consistent nonlinear beam-wave interaction, in which the multiple modes interaction with an electron beam and the mode coupling are taken into account. The influences of the current, the voltage, the magnetic coefficient, the velocity ratio of the electron beam on the multi-modes interaction with an electron beam are analysed. And, the connection between the modes in the complex cavity and the efficiency is researched also.