大功率高频电波加热电离层中参量衰减不稳定性研究(1):数值模拟  

Study of parametric decay instability in ionospheric heating of powerful waves(Ⅰ):Numerical simulation

作　　者：黄建 周晨[1] 刘默然 王翔[1] 张援农[1] 赵正予[1] HUANG Jian ZHOU Chen LIU Mo-Ran WANG Xiang ZHANG Yuan-Nong ZHAO Zheng-Yu(Department of Space Physics, School of Electronic Information, Wuhan University, Wuhan 430072, Chin)

机构地区：[1]武汉大学电子信息学院空间物理系,武汉430072

出　　处：《地球物理学报》2017年第10期3693-3706,共14页Chinese Journal of Geophysics

基　　金：国家自然科学基金面上项目(41574146);国家高技术研究发展计划项目(2014AAxxx1010A;2015AAxxx1010A)资助

摘　　要：参量衰减不稳定性(Parametric Decay Instability,PDI)在大功率高频(High frequency,HF)电波与电离层等离子体相互作用的过程中扮演着十分重要的角色,本文采用广义Zakharov方法对常规的等离子体流体力学方程组进行相应处理后,并在近似实际的电离层背景和电波传播模型下,构建了高频电波加热电离层激发PDI的数值计算模型.模拟结果发现:在毫秒量级的时间尺度上,大功率高频电波在寻常波(Ordinary wave,O波)反射点高度附近激发出了朗缪尔波(Langmuir wave)和离子声波(Ion-Acoustic wave)两种等离子体静电波模,模拟中产生的朗缪尔波和离子声波相应波数为5~11rad·m^(-1),结果与利用色散关系求出的理论值4~7 rad·m^(-1)近似一致,密度扰动幅值从10~6m^(-3)量级指数级增长到了10^(10)m^(-3)量级,直至能显著影响与"低频"密度背景相关的等离子体频率后,出现了等离子体"空穴"结构以及朗缪尔波被"俘获"现象,在扰动空间内的小尺度静电场幅值最高能达到100 V·m^(-1)量级,最终造成一种强烈的局地化"空穴"湍流现象.本文的研究有助于深入理解PDI的物理机制,对研究大功率高频电波与电离层等离子体之间复杂的非线性相互作用也有着非常重要的意义.Parametric decay instability （PDI） plays an important role in the interaction between high-powerful HF electromagnetic （EM） waves and ionosphere plasma. In order to study the PDI,a numerical simulation model has been created in this article. The generalized Zakharov method was used to process the routine plasma dynamic equations accompanied with a radio wave propagation model and background plasma density close to the actual ionosphere. Simulation results indicated that high-powerful HF EM waves can excite two electrostatic （ES） wave modes which are Langmuir and Ion-Acoustic waves near the reflection point of the ordinary waves （O-mode） at a millisecond timescale. The wave number of the two electrostatic wave modes in the simulation is about 5~11 rad·m-1 which is largely consistent with the theoretical results 4~7 rad·m-1 calculated by their dispersion relation. The perturbation density amplitude grows exponentially from 106 m-3 to 1010 m-3 till significantly influencing the plasma frequency correlated to ‘low frequency’ density of background plasma. Then it is followed by plasma cavitation structure and trapped Langmuir waves. Amplitude of the electrostatic field in the disturbance area can reach to 100 V·m-1. Finally it leads to an intense localized cavitation turbulence. Study in this article contributes to a deep comprehension for the PDI physical mechanism. It is also helpful to study the complex nonlinear interaction between high-power HF EM waves and ionosphere plasma.

关 键 词：大功率高频电波 波一波非线性耦合 有质动力 参量衰减不稳定性 朗缪尔波 离子声波 “空穴”湍流 “俘获”朗缪尔波 

分 类 号：P352[天文地球—空间物理学]