Simulation of mode conversion at the magnetopause  

作　　者：LIN Yu JOHNSON Jay WANG XueYi LU QuanMing 

机构地区：[1]Physics Department, Auburn University, Auburn 36849, USA [2]Department of Geophysics and Planetary Science, University of Science and Technology of China, Hefei 230026, China [3]princeton Plasma Physics Laboratory, Princeton University, Princeton 08543, USA

出　　处：《Chinese Science Bulletin》2012年第12期1375-1383,共9页

基　　金：supported by NSFC grants(41028003 and 40890163);NSF grants(ATM-0852682 and ATM-0646442);NSF grant ATM0902730;NASA grant NNX10AK97G to Auburn University;at PPPL by NASA grants(NNG07EK69I,NNH07AF37I,NNH09AM53I,NNH09AK63I,and NNH11AQ46I);DOE con-tract DE-AC02-09CH11466

摘　　要：Two-dimensional(2-D)and three-dimensional(3-D)hybrid simulations are carried out for mode conversion from fast mode compressional wave to kinetic Alfvn waves(KAWs)at the inhomogeneous magnetopause boundary.For cases in which the incident fast wave propagates in the xz plane,with the magnetopause normal along x and the background magnetic field pointing along z,the 2-D (xz)simulation shows that KAWs with large wave number kxρi～1 are generated near the Alfve′n resonance surface,whereρi is the ion Larmor radius.Several nonlinear wave properties are manifest in the mode conversion process.Harmonics of the driver frequency are generated.As a result of nonlinear wave interaction,the mode conversion region and its spectral width are broadened.In the 3-D simulation,after this first stage of the mode conversion to KAWs with large kx,a subsequent generation of KAW modes of finite ky is observed in the later stage,through a nonlinear parametric decay process.Since the nonlinear cascade to ky can lead to massive transport at the magnetopause,the simulation results provide an effective transport mechanism at the plasma boundaries in space as well as laboratory plasmas.Two-dimensional （2-D） and three-dimensional （3-D） hybrid simulations are carried out for mode conversion from fast mode com- pressional wave to kinetic Alfv6n waves （KAWs） at the inhomogeneous magnetopause boundary. For cases in which the incident fast wave propagates in the xz plane, with the magnetopause normal along x and the background magnetic field pointing along z, the 2-D （xz） simulation shows that KAWs with large wave number kxpi - 1 are generated near the Alfv6n resonance surface, where Pi is the ion Larmor radius. Several nonlinear wave properties are manifest in the mode conversion process. Harmonics of the driver frequency are generated. As a result of nonlinear wave interaction, the mode conversion region and its spectral width are broadened. In the 3-D simulation, after this first stage of the mode conversion to KAWs with large kx, a subsequent generation of KAW modes of finite ky is observed in the later stage, through a nonlinear parametric decay process. Since the nonlinear cascade to ky can lead to massive transport at the magnetopause, the simulation results provide an effective transport mechanism at the plasma boundaries in space as well as laboratory plasmas.

关 键 词：模拟模式 磁层顶 等离子体边界 模式转换 非线性波 非线性参数 波动力学 混合模拟 

分 类 号：P318[天文地球—固体地球物理学]