Whistler turbulence: Particle-in-cell simulations
Whistler turbulence: Particle-in-cell simulations
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DOI：
10.1063/1.2997339
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发表时间：
2008-10
影响因子：
2.2
通讯作者：
S. Saito;S. Gary;Hui Li;Y. Narita
中科院分区：
文献类型：
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作者：
S. Saito;S. Gary;Hui Li;Y. Narita
在磁化的、均匀的、无碰撞的电子-质子等离子体中的二维电磁粒子模拟显示了哨声湍流的前向级联。模拟代表衰减湍流，其中波数kc scincoe <$0.1处的初始窄带波动谱向kc scincoe <$1.0处的增加阻尼级联，其中c scincoe是电子惯性长度。湍流显示的磁能谱是波数的相对陡峭的函数，并且是各向异性的，在相对垂直于背景磁场Bo=xBo的方向上比在平行于Bo的相同波数处具有更多的能量。在弱湍流区，模拟的主要新结果如下：（1）随着涨落能量的增加，级联涨落的磁谱变得更加各向异性;（2）三个磁能比，δBj_2，δBj_2（j=x，y，z）与波矢的关系与哨声的线性色散理论符合得很好。（3）在弱湍流区，级联涨落的磁谱随涨落能量的增加而变得更加各向异性。
Two-dimensional electromagnetic particle-in-cell simulations in a magnetized, homogeneous, collisionless electron-proton plasma demonstrate the forward cascade of whistler turbulence. The simulations represent decaying turbulence, in which an initial, narrowband spectrum of fluctuations at wavenumbers kc∕ωe≃0.1 cascades toward increased damping at kc∕ωe≃1.0, where c∕ωe is the electron inertial length. The turbulence displays magnetic energy spectra that are relatively steep functions of wavenumber and are anisotropic with more energy in directions relatively perpendicular to the background magnetic field Bo=xBo than at the same wavenumbers parallel to Bo. In the weak turbulence regime, the primary new results of the simulations are as follows: (1) Magnetic spectra of the cascading fluctuations become more anisotropic with increasing fluctuation energy; (2) the wavevector dependence of the three magnetic energy ratios, ∣δBj∣2∕∣δB∣2 with j=x,y,z, show good agreement with linear dispersion theory for whistl...