高功率微波在低电离层中传输特性分析

Characteristic of high-power microwave propagating through lower ionosphere

高功率微波在大气中传输有一个衰减较大的高度,在这一高度,微波的强电场容易使大气电离形成等离子体,从而引起较大的非线性衰减,极端情况下会产生大气击穿.在低电离层(50～100 km),自然电离产生的电子浓度较高.主要研究高功率微波在低电离层的传输衰减特性.计算表明,在50 km高空,非线性吸收衰减最大,该高度也是最容易产生击穿的地方.在同样的电场强度下,脉宽越窄,衰减系数越小,衰减越小.在低电离层区间内,大气压强越小,吸收越小.

Severe attenuation happens when the high-power microwave propagates through a certain altitude. At this altitude, the microwave pulse will ionize the surrounding air and create a plasma, so the severe nonlinear attenuation will be caused, even the breakdown will happen. At the lower ionosphere, the density of the natural ionized free electrons is very intensive. The characteristic of the attenuation when high-power microwave propagates through the lower ionosphere is analyzed in this paper. Calculations indicate that the maximal nonlinear absorption attenuation occurs at the altitude of 50 km. This altitude is very possible to be breakdown. At the same electric-field intensity, the narrower the pulse duration is, the smaller the attenuation coefficient is. At the lower ionosphere, the attenuation decreases with decrease of the atmosphere pressure intensity.