The Oblique Alfvén Ion Beam Instability in the Earth’s Ion Foreshock  

作　　者：Yuhang Yao Jinsong Zhao Huasheng Xie Wen Liu Dejin Wu 

机构地区：[1]Key Laboratory of Planetary Sciences,Purple Mountain Observatory,Chinese Academy of Sciences,Nanjing 210023,China [2]School of Astronomy and Space Science,University of Science and Technology of China,Hefei 230026,China [3]Hebei Key Laboratory of Compact Fusion,Langfang 065001,China [4]ENN Science and Technology Development Co.,Ltd.,Langfang,065001,China

出　　处：《Research in Astronomy and Astrophysics》2023年第2期177-186,共10页天文和天体物理学研究（英文版）

基　　金：supported by the National Key R&D Program of China 2021YFA1600502(2021YFA1600500);the NSFC 41974203。

摘　　要：How ions evolve in the Earth’s ion foreshock is a basic problem in the heliosphere community,and the ion beam instability is usually proposed to be one major mechanism affecting the ion dynamics therein.This work will perform comprehensive analyses of the oblique ion beam instability in the Earth’s ion foreshock.We show that in addition to two well-known parallel instabilities (i.e.,the parallel fast-magnetosonic whistler instability and the parallel Alfvén ion cyclotron instability),the oblique Alfvén ion beam (OA/IB) instability can also be triggered by free energy relating to the relative drift d V between the solar wind proton and reflected proton populations.For slow d V (e.g.,d V■2.2V_(A),where VAdenotes the Alfvén speed),it only triggers the OA/IB instability.When d V■2.2V_(A),the growth rate in the OA/IB instability can be about 0.6 times the maximum growth rate in parallel instabilities.Moreover,this work finds the existence of two types of OA/IB instabilities.The first one appears at slow d V and in the small wavenumber region at fast d V,and this instability can be described by the cold fluid model.The second one arises in large wavenumber regions at fast d V,and this instability only appears in warm plasmas.Furthermore,through the energy transfer rate method,we propose that the OA/IB instability is driven by the competition among the Landau and cyclotron wave-particle interactions of beam protons,the cyclotron wave-particle interaction of core protons,and the Landau wave-particle interaction of electrons.Because oblique waves can experience significant damping,the importance of the OA/IB instability may be the effective heating of ions in the Earth’s foreshock.

关 键 词：plasmas-instabilities-waves-(Sun:)solar-terrestrial relations 

分 类 号：P353[天文地球—空间物理学]