为了简便快捷地计算微波击穿电场, 依据电子扩散模型的基本理论, 结合气体放电的基本参量, 应用特征扩散长度的概念, 给出了适合于规则结构微波部件的击穿电场的计算方法。为避免各种气体参数的不确定性对计算准确度的影响, 对等效直流电场与特征扩散长度之间的实验关系进行了拟合, 并根据等效直流电场的定义, 得出了一个适用于较高气压范围的击穿电场计算表达式。为了将该计算表达式扩展到更低的气压范围, 综合考虑了电子扩散模型和基于二次电子发射现象的真空微放电机理, 引入了一个合理形式的等效扩散长度, 进一步给出了适合于更广气压范围的微波击穿电场的计算表达式, 计算结果更符合A.D.Macdonald的实验结果。

For calculating microwave breakdown electric field in air simply and instantly, we give a new formula adopting characteristic diffusion length, which is combined with basic parameters in gas discharge and based on electron diffusion model. We fit the relationship between equivalent direct-current electric field and characteristic diffusion length from experiment recorded by A D Macdonald (1966), thus to avoid the influence of uncertainty of gas parameters on calculation accuracy. According to the definition of equivalent direct-current electric field, we give another formula to calculate breakdown electric field, which applies to a high air pressure. Also, in consideration of electric diffusion model and vacuum multipactor discharge based on secondary electron emission, we further give a formula applicable to a wide air pressure range by using a rational equivalent diffusion length. Compared with the formula by Yu Ming (2007), our results are more consistent with Macdonald’s experimental value.