多种微波模式下介质窗击穿的三维电磁数值算法及模拟研究

The dielectric window breakdown is a key problem that hinders the development of high power microwaves. Numerical simulation methods are usually used to study the dielectric window breakdown due to its complex physical processes. At present, microwave magnetic fields and microwave modes，which play important roles in the dielectric window breakdown, are usually ignored in the numerical simulations of one-dimensional electrostatic model. In this project, a three-dimensional electromagnetic numerical method, which can accurately simulate microwave magnetic fields and microwave modes, is adopted to conduct numerical research on the breakdown of dielectric window. Firstly, the physical processes and numerical algorithms of the microwave propagation, secondary electron multipactor, desorbed gases and gas discharges in the process of dielectric window breakdown are studied, and a three-dimensional electromagnetic numerical simulation software for the dielectric window breakdown is developed. The reliability of the software is verified by relevant theories and experimental results. Then, on the basis of the software, numerical simulation studies, along with theoretical studies, are going to be conducted for the dielectric window breakdown, in order to reveal the effect of some parameters (such as microwave magnetic field, microwave mode, microwave frequency, pulse width, shape of waveguide, shape of dielectric surface，and material properties) on the dielectric window breakdown. At last, the shape of dielectric surface, and material properties of dielectric window are optimized to suppress the dielectric window breakdown, and to help promote the practical application of high power microwave devices.

介质窗击穿是阻碍高功率微波发展的一个关键问题，由于其物理过程复杂，常采用数值模拟方法进行研究。目前常见的一维静电型数值模拟研究通常忽略微波磁场与微波模式，然而微波磁场与微波模式却可对介质窗击穿有较大影响。本项目拟采用三维电磁数值模拟方法对介质窗击穿进行数值研究，该方法可准确模拟微波磁场与微波模式。首先，对介质窗击穿过程中的微波传播、二次电子倍增、介质窗释气、气体放电等物理过程及相关数值算法进行研究，研制介质窗击穿的三维电磁数值模拟软件，并以相关理论与实验结果对软件可靠性进行验证；接着，以该软件为基础，对介质窗击穿进行理论及数值模拟探索，研究微波磁场、微波模式、微波频率、脉冲宽度、波导形状、介质窗表面形状及材料特性等参数对介质窗击穿的影响规律，优化介质窗表面形状及材料特性等参数以更好地抑制介质窗击穿，帮助推进高功率微波器件的实用化。

本课题旨对介质窗击穿的物理过程及相关数值算法进行研究，研制介质窗击穿的三维电磁数值模拟软件，并对介质窗击穿进行理论及数值模拟探索研究，主要包括以下几个方面的内容：1．介质窗击穿的电磁数值算法研究。在课题组已有的三维电磁粒子模拟平台上，完善了次级电子倍增及释气击穿等算法模块，开发了针对介质窗击穿的宏粒子合并算法，软件能对多种微波模式下的介质窗击穿进行数值模拟。2．介质窗击穿过程的研究。结合理论分析及数值模拟，对次级电子倍增现象、释气击穿等介质窗击穿过程进行了研究，研究了微波磁场及多种微波模式等因素的影响规律。3．介质窗击穿抑制的研究。探索了外加磁场、刻槽等因素对介质窗击穿抑制的影响规律。