Parametric instability in the solar wind: numerical study of the nonlinear evolution
Parametric instability in the solar wind: numerical study of the nonlinear evolution
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太阳风中的参数不稳定性：非线性演化的数值研究
DOI：
10.1063/1.1618645
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发表时间：
2003
期刊：
影响因子：
--
通讯作者：
P. Veltri
中科院分区：
文献类型：
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作者：
L. Primavera;F. Malara;P. Veltri
一个可能的机制来解释的Alfvenic相关性的减少与距离太阳，在太阳风的快速流中观察到的，是参数不稳定性。从圆偏振阿尔芬波开始，这种不稳定性通过破坏波的初始相关性而自然地产生向后传播的波和压缩波动。然而，这种机制对太阳风的适用性是有争议的，因为当等离子体β远低于1且初始波是单色时，它的效果更好。为了更好地阐明这一现象，我们通过使用伪谱一维MHD代码数值模拟了均匀背景磁场上Alfven波湍流谱的传播。我们使用的等离子体β值约为1和非常高的物理扩散系数值，通过使用“人工”数值扩散系数，以确保数值方案的稳定性。我们发现，即使在这样的条件下，最初的铝…
A possible mechanism to explain the decrease of the Alfvenic correlation with the distance from the sun, observed in fast speed streams in the solar wind, is the parametric instability. Starting from a circularly polarized Alfven wave, this instability naturally produces backward propagating waves and compressive fluctuations, by destroying the initial correlation of the wave. However, the applicability of this mechanism to the solar wind is debatable, since it works better when the plasma beta is much lower than 1 and the initial wave is monochromatic. To elucidate better this phenomenon, we numerically simulated the propagation of a turbulent spectrum of Alfven waves on a uniform background magnetic field by using a pseudo‐spectral, one dimensional, MHD code. We used values of the plasma beta about one and very high values of the physical diffusivities, by using “artificial” numerical diffusivities to ensure the stability of the numerical scheme. We found that, even under such conditions, the initial al...