空间微波器件介质微放电的形成及自熄灭机制研究

Multipactor is the principal failure mode of microwave devices for space applications, so multipactor mechanism investigation and threshold prediction become the key issue for device design in the ground stage. Present development of deep-space exploration technology and high-quality satellite communication technology requires to increase the power capacity of microwave devices and decrease their volume and weight concurrently, which accordingly popularizes the application of dielectric material in microwave devices but also results in more risk of multipactor between metal and dielectric surfaces. However, in comparison with multipactor between metal surfaces, the formation mechanism and physical phenomenon of multipactor between metal and dielectric surfaces are obviously more complicated and diverse, and there even exists unique self-extinguishing phenomenon. In order to fulfill the statistical modelling of multipactor between metal and dielectric surfaces, this project proposes one general and hybrid modelling approach of multipactor statistical theories as well as analytical models of dielectric surface charge, space charge and induced charge. On that basis, this statistical model is utilized to investigate the multipactor formation and evolution procedure in dielectric-loaded parallel-plate transmission lines, and analyze multipactor self-extinguishing regime and explore new possible multipactor modes. Meanwhile, multipactor threshold analysis is conducted to establish the device design principal for dielectric material option and geometric optimization, and then verified with three-dimensional PIC simulations and experimental measurements. Finally, the principal is applied for the performance improvement of present dielectric resonator filters. This project provides theoretical basis and design tools for multipactor investigation and prediction of microwave devices including dielectric layers in the aerospace field.

微放电作为空间微波器件的主要失效模式，其机理分析与阈值预测是地面设计阶段急需解决的关键问题。深空探索、高质量卫星通信与遥感等技术的发展要求不断提高微波器件的功率容量、并减小其体积和重量，该趋势加速了微波器件的介质化，但也增加了发生介质微放电的风险。与金属微放电相比，介质微放电的形成机制更加复杂、物理现象也更多样化，甚至会出现独特的“自熄灭”现象。本项目通过提出通用的微放电统计理论混合建模方法，并建立介质表面累积电荷、空间电荷及其感应电荷的作用模型，实现介质微放电的统计理论建模。利用该模型分析介质填充平板传输线中微放电的形成与演化过程，研究“自熄灭”现象的产生根源以及可能的微放电新模式，并通过微放电阈值分析确立介质材料选材和结构优化的器件设计原则。最后结合粒子模拟与实验验证，对现有的介质谐振腔滤波器进行优化。本项目为我国航天领域微波器件介质微放电的分析预测提供理论依据和设计工具。

建立了微波器件介质微放电的统计理论模型，采用介质表面积累电荷、空间电荷及其感应电荷的一维场作用模型，结合多层背景电荷层扰动法实现静电场分布与微放电电荷变化趋势的耦合求解，结果表明其可以准确模拟介质微放电的形成与演变过程；对介质填充平行平板微放电的建立与演化过程进行了粒子模拟分析，确定了典型介质材料下的微放电模式与形成机理，结果表明介质与金属二次电子发射系数的第一交叉动能点大小以及微波电压条件是影响介质微放电模式的关键因素；构建了一种基于混合敏感区域的介质微放电趋势判断图，通过介质面和空间总二次电子倍增率的敏感区域交叠情况，确定得到介质微放电发生自熄灭与饱和的参数条件，并形成介质微放电自熄灭现象的有效判断方法；结合统计理论与粒子模拟分析了介质材料与结构参数以及介质表面初始带电情况对介质微放电阈值的影响规律，确立得到空间微波器件介质选材和结构优化的设计原则，并形成利用介质表面初始带电的介质微放电抑制方法。本项目研究为微波器件介质微放电的分析与预防提供重要的理论依据和设计工具，对进一步提升我国航天电子器件的功率水平有重要的科学意义和应用价值。