On the use of atmospheric pressure plasmas as electromagnetic reflectors and absorbers
On the use of atmospheric pressure plasmas as electromagnetic reflectors and absorbers
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DOI：
10.1109/27.57528
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发表时间：
1990-08
影响因子：
1.5
通讯作者：
R. Vidmar
中科院分区：
文献类型：
--
作者：
R. Vidmar
讨论了地球大气层中从海平面到100千米的稀薄人造等离子体。一个电离源产生一种稀薄等离子体，其电子数密度\(n_{e}\)在源附近较高，并随着与源的距离增加而降低。在源关闭后，\(n_{e}\)作为时间的函数而降低，因为电子与正离子复合或附着到负离子上。讨论了对于理解这些可被建模为冷碰撞等离子体的等离子体至关重要的电磁特性。介绍了气体和等离子体的特性，例如动量转移碰撞率、等离子体寿命、复合动力学以及惰性气体的影响。对大气压下的典型碰撞率和等离子体寿命进行了量化。讨论了具有梯度的等离子体的应用。它们包括一种能从高频到甚高频反射或吸收的高空等离子体以及一种宽带大气压吸收体。描述了等离子体的产生和使用，包括用高能电子束源进行电子碰撞电离以及碱金属蒸汽或诸如四（二甲基氨基）乙烯（TMAE）等有机蒸汽的紫外光电离。对维持等离子体所需的功率进行了量化，并讨论了诸如最大吸收和带宽等特性。在最大吸收、吸收带宽、占空比和施加功率之间进行权衡，可以主要在甚高频对吸收进行优化。
Tenuous man-made plasmas in the Earth's atmosphere from sea level to 100 km are discussed. An ionization source generates a tenuous plasma with an electron number density n/sub e/ that is high near the source and diminishes with distance from the source. After the source shuts off, n/sub e/ decreases as a function of time as electrons recombine with positive ions or attach to negative ions. The electromagnetic properties that are essential to an understanding of these plasmas, which can be modeled as cold collisional plasmas, is discussed. Gas and plasma characteristics, such as momentum-transfer collision rate, plasma lifetime, recombination kinetics, and the effect of noble gases, are presented. Typical collision rates and plasma lifetimes at atmospheric pressure are quantified. Applications for a plasma with a gradient are discussed. They include a high-altitude plasma that can reflect or absorb from HF to VHF and a broadband atmospheric pressure absorber. The generation and use of plasma, including electron impact ionization with a high-energy electron-beam source and UV photoionization of an alkali vapor or an organic vapor such as tetrakis (dimethylamino)ethylene (TMAE), is described. The power required to sustain a plasma is quantified, and properties such as maximum absorption and bandwidth are discussed. Tradeoffs among maximum absorption, absorption bandwidth, duty ratio, and applied power permit optimization of absorption primarily at VHF. >