开放空间重复频率微波脉冲击穿概率理论与实验研究

Statistical characteristics of S-band microwave pulse breakdown time in free space

综合考虑有效初始电子产生理论、雪崩电子击穿理论等过程中的击穿延迟时间,探讨了开放空间微波脉冲的击穿延时概率分布,提出了重复频率微波脉冲击穿概率模型,定义了基于概率模型的微波脉冲击穿阈值。利用S波段微波准光学反射聚焦系统对一定气压大气击穿过程进行了模拟,监测击穿放电发光时刻作为击穿时间,分别在铯137放射源存在与否情况下开展了系列实验。研究结果表明,提高种子电子产生率相较于提高电离率是增大脉冲击穿概率更有效的方法;重复频率过程中,若存在累积效应,击穿延时概率分布曲线将左移并趋于稳定,击穿后的气体在短时间内容易再次击穿。

In the vicinity of atmospheric breakdown threshold,microwave pulse breakdown discharge becomes a probabilistic problem,which is closely related to breakdown time.When atmospheric breakdown occurs,the transmission pulse width and peak power will be shortened.The development of high power microwave technology is severely restricted by the hazards.To study the breakdown problem in high power microwave atmospheric transmission,the probability distribution curves of breakdown time in different processes are compared,and the effects of ionization rate and seed electron generation rate on breakdown time are discussed.The breakdown process of free space microwave was experimentally studied using S-band high power microwave pulse source.The breakdown time of plasma was monitored by photomultiplier tube,and a series of experiments were carried out in the presence or absence of cesium 137 seed electron source.The results show that increasing the seed electron generation rate is a more effective method to increase the pulse breakdown probability.In the process of repetition frequency,if there is cumulative effect,the breakdown delay time probability distribution curve will move to the left and tend to be stable.And the gas after breakdown will be easy to breakdown again in a short time.