波模并合激发谐频脉泽辐射的泵波模拟  

Simulation on the Mechanism of Harmonic Maser Emission Through the Wave Coalescence Process

作　　者：刘功林 宁昊 倪素兰 李传洋 张子龙 李耀坤 陈耀[1,2] LIU Gonglin;NING Hao;NI Sulan;LI Chuanyang;ZHANG Zilong;LI Yaokun;CHEN Yao(Institute of Space Sciences,Shandong University,Weihai 264209;Institute of Frontier and Interdisciplinary Science,Shandong University,Qingdao 266237;School of Physics and Electronic Information,Yantai University,Yantai 264005;College of Physics and Electronic Information,Dezhou University,Dezhou 253023)

机构地区：[1]山东大学空间科学研究院,威海264209 [2]山东大学前沿交叉科学青岛研究院,青岛266237 [3]烟台大学物理与电子信息学院,烟台264005 [4]德州学院物理与电子信息学院,德州253023

出　　处：《空间科学学报》2025年第1期56-65,共10页Chinese Journal of Space Science

基　　金：国家自然科学基金项目(12203031,12103029);中国博士后科学基金项目(2022TQ089);山东省自然科学基金项目(ZR2021 QA033,ZR2023 QA141)共同资助。

摘　　要：损失锥电子驱动的电子回旋脉泽辐射是解释太阳射电尖峰暴的主要机制,然而在强磁化条件下,其主要激发的基频辐射在日冕中存在逃逸困难的问题,谐频辐射的激发可有效解决该问题.最近有研究提出一种新型谐频辐射机制,即损失锥电子激发的基频X模(X1)和Z模通过波模并合产生谐频辐射.然而其相应非线性波模并合过程仍需进一步研究和论证.研究针对Z+Z和Z+X1并合产生谐频的新型辐射机制开展了并合条件分析,发现该过程的并合条件很容易满足,并可在很宽的传播角范围内激发谐频X2辐射.基于此开展泵波粒子模拟可验证非线性波模并合过程的发生,模拟得到谐频辐射的有效激发,且并合过程能量转换率在2%~8%.Electron Cyclotron Maser Emission(ECME)driven by electrons with loss-cone distribution is the main mechanism for explaining solar radio spikes.However,in strongly magnetized plasmas,the losscone-driven ECME mainly generates fundamental X mode emissions,which can be efficiently absorbed when escaping through the second-harmonic layer in the solar corona.To solve the“escaping difficulty”,recent studies suggested a new mechanism of harmonic maser emission(X2)involving nonlinear wave coupling process of Z-mode and fundamental X-mode(X1)waves(Z+Z→X2,Z+X1→X2).It is necessary to verify the nonlinear wave coalescence process with theoretical analyses and numerical simulations.Here,the possibility of a nonlinear wave coupling process is examined via solving the matching conditions for three-wave resonant interaction based on the dispersion relation of cold plasma in magneto-ionic theory.The matching conditions for the Z and/or X1 waves were found to be satisfied over a wide range of parameters,leading to the production of X2 emissions that propagate perpendicularly and obliquely relative to the direction of the background magnetic field.Based on the solutions obtained in the matching condition analysis,we selected four sets of solutions of Z+Z and Z+X1 to perform particlein-cell simulations using wave pumping method,to verify the nonlinear process of wave coalescence generating second harmonic X-mode emissions.With X1 and/or Z modes correctly pumped in the simulation domain,efficient generation of X2 emissions was observed,with saturation achieved within 400 Ω_(ce)^(-1).The conversion rate of energies of X2 emissions to Z mode waves varies from 2% to 8%.The study presents strong evidence to support the new mechanism of harmonic maser emission,which can be widely applied to explain the solar and space radio emissions.

关 键 词：相干辐射机制 PIC模拟 太阳射电辐射 非线性过程 

分 类 号：P354[天文地球—空间物理学]