国内高功率微波大气传播研究的若干进展

Recent Progress on the Study of High-Power Microwave Propagation in the Atmosphere in China

近年来,高功率微波系统的输出功率越来越高,气体击穿已成为限制高功率微波传播的主要因素之一,对其开展研究具有重要的应用意义。文中首先简单回顾了国内同行的研究成果,然后重点介绍了我们已取得的代表性进展。针对由麦克斯韦方程组和电子流体力学方程组构建的高功率微波大气传播的电子流体模型,提出了该模型的时域有限差分算法。推导了超宽带脉冲的等效电场,并将其代入电离参数的经验表达式,研究了超宽带脉冲大气传播与击穿;基于分区域技术,发展了高功率微波长距离传播的快速算法;将改进的电子能量分布函数引入流体模型,计算了不同压强下的击穿时间,发现其与粒子模拟的结果符合得很好;在充分考虑电子与空气-六氟化硫混合气体之间的微观反应的情况下,研究了六氟化硫的填充比例对混合气体击穿阈值的影响。

Researches on the high-power microwave （HPM） propagation in the atmosphere are very important, since gas breakdown has become one of major factors to hinder HPM propagation with the output power of the high power microwave （HPM） increasing in recent years. First, the theoretical and experimental progress for HPM propagation in the atmosphere in china is reviewed briefly. Next, several of our typical research advances are introduced in detail. The fluid model including Maxeell＇s equations and a set of electron-fluid equations is proposed to study the HPM propagation in the atmosphere, which is solved numerically by the finite-difference time-domain method. The effective electric field of the ultra-wideband pulse, which is derived from the electron momentum equation, is substituted into the empirical formulas for ionization parameters, and the gas breakdown driven by the pulse is investigated. Using the space-domain decomposition, a fast method is devel- oped to simulate the long-distance propagation of the HPM. The improved electron energy distribution function is introduced into the fluid model, and the breakdown time over a wide pressure range is estimated, which is very well matched with the re- suits of Particle-in-cell-Monte Carlo collision （PIC-MCC） simulations. Various reactions between electrons and the mixture of air and SF6 are taken into account, and the effect of the ration of SF6 to the mixture on the breakdown threshold is investi- gated.