Study on Absorption Characteristics of Electromagnetic Wave in Thin Plasma Slab

The absorption characteristics of thin plasma slab are investigated by analyzing isotropy plasma with different thicknesses. When the width of the plasma slab is sufficiently thin, the electromagnetic wave can be transmitted, even if the incidence frequency is low, because of the tunneling effect. The influence of incident wave frequency and incident angle on the absorptivity of electromagnetic wave about tunneling effect is discussed in this paper. Generally, an absorption band created by non-magnetized plasma can be found in the tunneling frequency band (0 <= omega <= 1), and the peak frequency is the same as that of the plasma frequency, that is, omega = 1. When the thickness of plasma slab is decreased, another absorption band is gradually generated at omega = 0. It is demonstrated that the absorption band at omega = 0 is in parallel with the absorption band at omega = 1. The absorption characteristics of electromagnetic wave in tunneling frequency band are quite different from those of non-magnetized plasma because magnetized plasma is anisotropic medium. Two absorption bands are formed in right-handed circularly polarized wave (RCP wave), which are cyclotron resonance absorption band and collision absorption band. The two absorption bands are bent due to the cyclotron frequency and incident angle. However, only one collision absorption band can be found in left-handed circularly polarized wave (LCP wave). The distribution regulars of absorption bands formed by the two polarization modes in the range of 0 <= omega(b) <= 2 and 0 degrees <= theta <= 90 degrees are researched. The collision absorption bands of LCP wave and RCP wave are found to be reciprocal in the range we studied. The distribution maps of the absorption band as functions of omega(b) and theta are achieved by curve fitting. The reciprocal characteristic of collision absorption bands of LCP wave and RCP wave is verified. A method for measuring density of magnetized plasma is proposed based on the reciprocal relationship found in this paper.

Automated summary

The absorption characteristics of thin plasma slab with different thicknesses are studied, revealing the influence of incident wave frequency and angle on the absorptivity due to tunneling effect. Different absorption bands are observed, with one formed at omega = 1 and another generated at omega = 0 as the thickness of plasma slab decreases. The absorption behavior in tunneling frequency band is different for magnetized plasma, with two absorption bands found in right-handed circularly polarized wave and one in left-handed circularly polarized wave. The reciprocal relationship of the collision absorption bands in the two polarization modes is analyzed, providing a method for measuring density of magnetized plasma.