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Processes in the Current Disruption Region: From Turbulence to Dispersion Relation
Journal of Geophysical Research: Space Physics ( IF 2.6 ) Pub Date : 2020-12-11 , DOI: 10.1029/2020ja028404
L. V. Kozak 1, 2 , B. A. Petrenko 1 , A. T. Y. Lui 3 , E. A. Kronberg 4, 5 , P. W. Daly 4
Affiliation  

Using measurements from Cluster‐II space mission, we compared the characteristics of the fluctuations of the magnetic field magnitude and the Bz component in the current disruption (CD) regions. We used fast Fourier transform, statistical, and wavelet analysis, and wave surveyor technique on the multispacecraft measurements. Among the obtained results one can note the presence of spectral breaks in both the magnetic field magnitude and the Bz component at frequencies smaller or equal to the proton gyrofrequency. The numerical values of the spectral index for the magnetic field magnitude and for the Bz component are similar, and the nature of the turbulent processes is close to that of the homogeneous magnetohydrodynamic (MHD) (the spectral index varies from −2.00 to −1.31) on the large time scale and resembles Hall‐MHD (the spectral index varies from −2.33 to −2.99) on the smaller time scales. The kurtosis results are consistent with those of the spectral analysis. From wavelet technique, we detected powerful Pc4 and Pi1 pulsations, along with cascade features both for the magnetic field magnitude and for its z‐component. The dispersion ratios also indicate the presence of nonlinear energy cascade processes in CD regions. We have found that the pulsations observed for magnetic pressure are also present in thermal proton and electron pressures although their powers differ considerably. For the dynamic helium and oxygen pressures, and also for the thermal pressures of these components, only pulsations in the high‐frequency region are revealed.

中文翻译:

当前扰动区域的过程:从动荡到离散关系

使用来自Cluster-II太空任务的测量,我们比较了电流扰动(CD)区域中磁场强度和Bz分量的波动特征。我们在多宇宙飞船的测量中使用了快速傅立叶变换,统计和小波分析以及波测量器技术。在获得的结果中,可以注意到在小于或等于质子回转频率的频率下,磁场强度和Bz分量中都存在频谱破裂。磁场强度和Bz的光谱指数的数值成分相似,并且湍流过程的性质在较大的时间尺度上接近于均相磁流体动力学(MHD)(光谱指数从-2.00到-1.31),并且类似于Hall-MHD(光谱指数从-2.33至-2.99)。峰度结果与光谱分析的结果一致。通过小波技术,我们检测到强大的Pc4和Pi1脉动,以及磁场强度及其z分量的级联特征。色散比还表明在CD区域中存在非线性能量级联过程。我们已经发现,尽管在热质子和电子压力中也观察到了磁压脉动,但它们的功率相差很大。对于动态氦气和氧气压力,
更新日期:2021-01-16
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