极区受激电磁辐射实验研究  

Experimental study of stimulated electromagnetic emissions in polar region

作　　者：陈靓 杨巨涛[1] 何凌磊 李清亮[1] 郝书吉[1] 马广林[1] 闫玉波[1] 车海琴[1] 梁勇敢 李海英 张文超[1] CHEN Jing;YANG JuTao;HE LingLei;LI QingLiang;HAO ShuJi;MA GuangLin;YAN YuBo;CHE HaiQin;LIANG YongGan;LI HaiYing;ZHANG WenChao(National Key Laboratory of Electromagnetic Environment,China Research Institute of Radiowave Propagation,Qingdao Shandong 266107,China;College of Physics and Electronic Engineering,Nanyang Normal University,Nanyang Henan 473061,China)

机构地区：[1]中国电波传播研究所电波环境特性及模化技术重点实验室,山东青岛266107 [2]南阳师范学院,物理与电子工程学院,河南南阳473061

出　　处：《地球物理学报》2024年第7期2487-2495,共9页Chinese Journal of Geophysics

基　　金：电波环境特性及模化技术国家重点实验室基金(202003010,JCKY2023210C614240302);中国博士后科学基金(2020M672307);基础性科研院所稳定支持青年专项(A132301089-C01)资助。

摘　　要：受激电磁辐射(stimulated electromagnetic emissions, SEE)复杂的谱线特征,为研究电离层加热物理机制提供了强有力的研究手段.本文基于2017年和2022年我国学者利用EISCAT加热系统开展电离层加热实验期间的SEE数据,分析了加热电磁波的极化、频率、功率以及波束指向对SEE谱线特征的影响,研究结果表明:(1)相比于非寻常波,加热波为寻常波实验期间更易观测到丰富的SEE谱线结构,如频率上移分量最大值(upshifted maximum, UM)、热窄带连续谱(thermal narrow continuum, NCth)及向下偏移最大值(downshifted maximum, DM)等;(2)加热频率由4.07 MHz增至4.10 MHz,向下偏移峰值(downshifted peak, DP)频移与加热频率呈强线性相关,当加热频率达到电子回旋倍频时,DP和DM谱消失,上混杂波的产生过程被抑制.因此,结合电离层加热过程中DP和DM谱特征可以实时快速估算加热区内电子回旋频率的大小;(3)加热功率由24 MW增至192 MW,在DM和加热频率之间出现了一种新型下移谱特征,即中间向下偏移最大值(intermediate downshifted maximum, IDM),本实验中观测到UM随功率的变化是IDM相对于加热波频率的镜像行为;(4)结合超高频非相干散射雷达联合探测发现,加热波束指向为垂直方向逆时针夹角6°时,更易激励振荡双流不稳定性的密度纯增长模式,形成更多人工密度不均匀体,从而获得更强DM谱线.Stimulated electromagnetic emissions(SEE)with complex spectral features provide a powerful research tool are an effective tool to study the physical mechanism in ionospheric heating.In this paper,we investigate the effects of the polarization,frequency,power,and beam direction of the heating electromagnetic waves on the SEE spectral features during the ionospheric heating experiments conducted by our researchers using the EISCAT heating facilities in 2017 and 2022.The results show that:(1)A variety of SEE structures,including an upshifted maximum(UM),a thermal narrow continuum(NCth)and a downshifted maximum(DM),are more likely to be detected using heating wave with ordinary-mode polarization than with extraordinary-mode polarization.(2)The downshifted peak(DP)frequency offset exhibits a linear correlation with the heating frequency from 4.07 MHz to 4.10 MHz.When the heating frequency reaches the electron gyro-harmonic frequency,the DP and DM spectra disappear,and the process of the generation of the upper hybrid wave is suppressed.Therefore,the electron gyro-harmonic frequency can be rapidly estimated in real time by combining the DP and DM spectral features during the ionospheric heating process.(3)The intermediate downshifted maximum(IDM),a new type of downshifted spectral feature,appears between the DM and the heating wave frequency when heating power increases from 24 MW to 192 MW.It is observed that the dynamic behavior of UM mirrors IDM with respect to heating frequency.(4)In conjunction with the ultrahigh frequency incoherent scattering radar detection,it is found that the heating wave beam direction at an anticlockwise angle of 6°from vertical is more likely to excite the density pure-growing mode of the oscillating two-stream instability,which excites more artificial field-aligned irregularity structures and results in higher DM spectral intensity.

关 键 词：受激电磁辐射 电离层加热 人工沿场不均匀体 振荡双流不稳定性 

分 类 号：P352[天文地球—空间物理学]