基于分形的等离子体鞘套湍流随机相位屏模拟研究

项目名称： 基于分形的等离子体鞘套湍流随机相位屏模拟研究

项目编号： No.61301065

项目类型： 青年科学基金项目

立项/批准年度： 2014

项目学科： 无线电电子学、电信技术

项目作者： 李江挺

作者单位： 西安电子科技大学

项目金额： 23万元

中文摘要： 高速飞行器表面等离子体鞘套中的湍流微结构对飞行器的通讯联络产生不可忽略的影响，是飞行器空间通信亟待解决的关键课题之一。本项目以研究电磁波在等离子体鞘套湍流中的传播特性为目的，提出基于分形的等离子体鞘套湍流中电波传播随机相位屏方法。首先，针对等离子体鞘套湍流的非线性流动特性，建立可压缩湍流的大涡模型。其次，给出满足湍流脉动的速度远小于平均流动速度条件下，湍流介质的折射系数模型，推导穿过湍流电磁波波前分维及湍流频谱指数，建立等离子体鞘套湍流的分形模型。最终,采用随机中点位移算法以及多层特定分形指数的相位屏叠加法，模拟等离子体鞘套湍流对电磁波传播的影响，分析信号的色散、相位闪烁以及幅度闪烁。为研究再入过程中通信信号的随机起伏现象提供了一种可行的新思路，对飞行器无线信道特性分析具有指导性意义。

中文关键词： 等离子体鞘套；分形相位屏；高超声速湍流；折射率起伏功率谱；

英文摘要： Communications of flight vehicle is significantly affected by the microstructure of turbulent flow in plasma sheath of high-speed flight vehicle, which is one of the key tasks urgently to be solved with respect to space communications of flight vehicles. In this project, propagation properties of electromagnetic wave in turbulent flow of plasma sheath is studied; the ramdom phase screen method of radio wave propagation in the turbulent flow based on fractal is also proposed. Firstly, for the nonlinear flow characteristics of turbulent flow in plasma sheath, the large eddy model of compressible turbulent is created. Secondly, the refraction coefficient model of turbulence medium is proposed provided that the turbulent fluctuation speed is far lower than the average flow velocity, and also the fractal dimension of cross-turbulence electromagnetic wave-front and turbulent spectral index then can be concluded, thus the turbulent-flow fractal model of plasma sheath is established. Finally, the random midpoint displacement algorithm and phase screen superposition method of multilayer specific fractal index are adopted to simulate the influence of turbulent flow of plasma sheath on electromagnetic wave propagation and to analyze the signal dispersion, phase and amplitude scintillation. A feasible new method is pro

英文关键词： plasma sheath；fractal phase screen；hypersonic turbulence；Power spectrum of the refractive-index fluctuation；