多载波微放电中二次电子横向扩散的概率分析

长周期多载波微放电是近年来新发现的、主要发生在宽带、大功率真空微波部件中的二次电子倍增放电现象. 与发生在单个载波周期中的多载波微放电相比, 长周期多载波微放电来源于多个载波周期间的二次电子累积, 具有相对较低的放电阈值和不可预测性, 对空间和加速器应用中宽带大功率微波部件的长期可靠性带来了新的隐患. 为解决长周期多载波微放电阈值分析中非均匀场激励下二次电子累积的理论计算问题, 本文采用概率方法, 通过引入随机漫步和Branching Levy漫步模型, 对微放电过程中二次电子横向扩散所需遵循的概率模型进行了严格的推导, 并采用所得的概率密度函数, 给出了主模为TE₁₀模的矩形波导中多载波激励下二次电子积累过程的纯理论计算. 与相同条件下采用粒子仿真所得的结果对比, 本文给出的计算结果与仿真结果相符合, 同时计算耗时减少了接近一个数量级. 本文报道的二次电子横向扩散的概率描述可广泛应用于高功率真空电子和电磁器件领域. 关键词： 多载波微放电 二次电子 随机漫步 概率密度

Probabilistic analysis of the lateral diffusion of secondary electrons in multicarrier multipactor

Recently, a new mechanism of secondary electron multipaction, termed “long-term” multicarrier multipactor, was found in wideband high-power systems used in vacuum environments. Due to the long-term accumulation of secondary electrons between consecutive periods of the multicarrier signal, the long-term multicarrier multipactor has relatively low discharge threshold and is difficult to predict, thus causes potential reliability problems in space and accelerator applications. In this paper, we propose a stochastic approach to the analytical analysis of the multicarrier multipactor discharge occurring in inhomogeneous electric fields. By introducing the random walk and Levy walk theory, the probabilistic model of the lateral diffusion of secondary electrons in the process of a multipactor discharge is derived. Based on the derived probability density, the purely theoretical calculation of the accumulation of secondary electrons of a multicarrier multipactor in a rectangular waveguide supporting TE₁₀ mode is given. The theoretical results comply well with the results achieved by the time-consuming particle simulation, with reducing computational time by about one- order of magnitude. The presented probability density of the lateral diffusion of secondary electrons can have applications in high-power electronics and electromagnetism.
Keywords： multicarrier multipactor secondary electrons random walk probability density