Phase coherence in the solar wind MHD waves : Geotail data analysis and numerical simulation studies

太阳风 MHD 波的相位相干性：Geotail 数据分析和数值模拟研究

基本信息

批准号：
15540428
负责人：
HADA Tohru
金额：
$ 2.37万
依托单位：
KYUSHU UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2003
资助国家：
日本
起止时间：
2003 至 2004
项目状态：
已结题

项目摘要

By analyzing magnetic field data obtained by Geotail spacecraft, and also by performing numerical simulations of various systems modeling nonlinear coupling of MHD waves, we have made research on several issues related to the wave phases.1.We have developed a method to quantitatively evaluate the phase coherence among waves, by comparing structure functions of the original and its phase shuffled and phase correlated surrogates. Application of the method to Geotail magnetic field data revealed that the MHD waves in the foreshock is in fact phase correlated, and the correlation is stronger as the turbulence amplitude is increased. We have further identified the origin of the phase coherence by a method using the wavelet filtering technique.2.By numerical time integration of various systems which model the nonlinear coupling of MHD waves, such as the triplet model, multiply-coupled triplet model, the DNLS equation, and the Hall-MHD set of equations, we discussed the relationship between the phase coherence, nonlinear dispersion relations, and transfer of energy among the different waves (or eigenmodes). We showed that the phase coherence is self-generated as the energy is transferred between the waves, and the phenomena can be modeled by avalanches.3.By performing test particle simulations, we discussed diffusion and acceleration of energetic particles in the MHD turbulence with phase coherent structures. We argued the relationship between statistics of the particle transport and that of the field fluctuations.

通过分析通过地形尾航空航天器获得的磁场数据，并通过对MHD波的各种系统建模非线性耦合进行数值模拟，我们已经对与波浪相关的几个问题进行了研究。1.我们已经开发了一种定量评估波之间的相干性的方法，通过比较原始和相位的相位效果和相位的相对效果。该方法在码头磁场数据上的应用表明，前换货物中的MHD波实际上相关，并且随着湍流幅度的增加，相关性更强。 We have further identified the origin of the phase coherence by a method using the wavelet filtering technique.2.By numerical time integration of various systems which model the nonlinear coupling of MHD waves, such as the triplet model, multiply-coupled triplet model, the DNLS equation, and the Hall-MHD set of equations, we discussed the relationship between the phase coherence, nonlinear dispersion relations, and transfer of energy among the different波（或本征模）。我们表明，随着能量在波之间传递，相干性是自我生成的，并且现象可以通过雪崩建模。3。通过执行测试粒子模拟，我们讨论了MHD湍流中使用相位相干结构中能量颗粒的扩散和加速度的扩散和加速。我们争论了粒子传输的统计数据与场波动的关系之间的关系。