A Study Of Absorption And Reflection Of Electromagnetic In Plasma And Its Application

As a kind of special complicated dielectric, plasma will absorb and reflect EM-wave(electromagnetic wave). These characters have been widely used in radar detection, plasma stealth and protection of high frequency electromagnetic pulse. Research on absorption and reflection of EM-wave in plasma has playing an important role on the application of plasma.Plasma in nature exists in inhomogeneous distribution, this thesis discusses interaction between plasma and EM-wave. As two main description parameters of inhomogeneous plasma, peak electron density and collision frequency decide the absorbing and reflection property of EM-wave in plasma, so this thesis studies on the influence of absorption and reflection of EM-wave in plasma by peak electron density and collision frequency, analyze the rule of absorption and reflection when EM-wave incidents in different angles, put forward calculation method of absorption and reflection, simulate absorption and reflection of EM-wave in plasma covering conducting plate, obtain relationship between peak electron density、collision frequency and absorption、reflection.Plasma has strong ability of collisional absorption, it can be used for stealth. However, because of mismatch between plasma and free space, EM-wave is reflected heavily. To solve this problem, this thesis use the method that several layer material was used to match the impedance between plasma and free space and optimize the choice of layers. Apply GA(Genetic Algorithm) method to optimize and simulate and the result indicates that this method is available. Using this paper’s optimization method, a good stealth can be reached in VHF(very high frequency)、L、S、C and whole frequency band.