电磁波在高密度等离子体微柱腔体结构中的新传输模式

超高声速飞行器再入过程中会因为等离子体鞘层而产生通信中断,俗称"黑障".近些年人们针对黑障通信的研究虽取得了一些成果,但仍然没能从根本上解决问题.本文从电磁波在高密度等离子体柱中的传输机理研究出发,借鉴二维光子晶体和表面波局域耦合相关理论,设计出了一种新型的等离子体微柱腔体结构,在这种特殊结构下L和S波段的电磁波在某些频段内出现了不同寻常的传输现象,即从高密度等离子体柱的内部穿过.这种新结构下的传输模式将为黑障通讯研究提供新的技术途径和方法.

New transmission mode of electromagnetic wave in high-density rod cavity structure

During reentry of hypersonic spacecraft into the atmosphere, a break in the radio communication due to the presence of a plasma sheath on the spacecraft can occur. The break is commonly known as reentry communication blackout. Normally, for high density plasma, it is difficult for the electromagnetic waves of L and S bands to penetrate through. They may be decayed rapidly or reflected. That is why reentry communication blackout happens. In recent years, initiative methods are used to reduce the effects of reentry communication blackout such as by designing ideal shape for reentry vehicle, sprinkling special substances on the surface of the vehicle to improve efficiency of electromagnetic wave, adding magnetic field within the blackout area, etc. However, these methods not only fail to fully resolve the problems caused by blackout but also bring some new ones. Therefore, to resolve the problems, transmission mechanism of electromagnetic waves in plasmons should be analyzed. In this paper, we use the finite difference time domain, consider the mechanism of electromagnetic waves in a structure consisting of high-density plasma rods, and refer to the two-dimensional (2D) photonic crystal and surface wave local coupling theory. A new type of high-density plasma micro-rod cavity structure is designed. The special structure, consisting of metal cavity, high-density plasma rod, and dielectric medium filled within the cavity, is quite different from traditional 2D sub-wavelength plasma rod arrays. This kind of design takes advantage of cavity structure to couple electromagnetic wave within the plasma rod so that the surface wave diffraction transmission mode can be changed into a local coupling enhancement penetrating mode. In this paper, we investigate the plasma micro-rod cavity structures with two shapes:cylinder and square, respectively. It is found that electromagnetic waves of L and S bands can have unusual transmission properties in certain frequency ranges, such that electromagnetic waves can pass through the interior of the high-density plasma rod.