Three-dimension Partical Simulation Of Quasi-optical Cavity Gyro-TWT

The wavelength of millimeter wave band is 1mm~10mm, operating frequency between 30 GHz and 300 GHz. Because the frequency between the microwave and infrared, so there are two features of the short length and wide band. Cyclotron traveling wave amplifier that based on electron cyclotron maser effect is a high-power microwave device, Because of its high power and wide band output characteristics, in recent years,the study of such a device is getting more and more.However, with the increase of the operating frequency, Problems of wavelength-size-matching effect and power capacity have seriously restricted the speed of development. Conventional mean to solve this problem is to use higher-order mode as the operating mode of the cavity, but this way has brought the issue of mode competition. In the millimeter wave band, because the structure of the device is smaller,so the problem of mode competition will become more intense. It is appreciated, the study of interaction cavity with mode selective becomes a top priority in the millimeter wave band. Quasi-optical cavity is a structure with lateral opening, which has mode selection character because of diffraction loss, this character can be used to solve the mode competition problem. This paper studied the cyclotron traveling wave amplifier that’s interaction cavity is quasi-optical cavity. Because the gyro-twt is a kind of vacuum electron device based on electron cyclotron maser, This issue of electron cyclotron interaction with the electromagnetic field has become the focus of research.The studied details include:1. The reasons of restricting the development of cyclotron traveling wave amplifier were studied. The structure and theory of quasi-optical cavity were analyzed and researched. The Gaussian beam equations of quasi-optical cavity was depth studied.Getting the electromagnetic field distribution expression by deriving the equation. The problem of diffraction loss was learned for electromagnetic field in quasi-optical cavity.By comparing the density of dispersion curve at the circular waveguide and quasi-optical cavity, we can determined that structure with the feature of mode selection.Laid the foundation for suppressing the impact that model competition brings.2. Gyrotron kinetic theory was analyzed, and derived the dispersion curves equation. The suppression of truncated structure for backward wave oscillation wasresearched. Quasi-optical cavity cyclotron traveling wave amplifier was designed to operate in 140 GHz. And then this model was simulated.The suppression of truncated structure for backward wave oscillation was analyzed in this way data that got by simulating. the output of 820 W peak power and 3.5GHz bandwidth was got by suppressing backward wave oscillation and optimizing the structure parameters and electrical parameters.3. Traveling wave amplifier was designed working 210 GHz. And then 3D model was preliminary explored. In an initial electrical parameter, the output of 320 W peak power and 1.0GHz bandwidth was got by simulating.